This diagnostic trouble code (DTC) is a generic powertrain code. The P0504 code is considered a common code because it applies to all makes and models of vehicles. Although the specific repair steps may vary slightly depending on the model.
Your vehicle's powertrain control module (ECU) issues a P0504 code in response to a recognized failure in the brake light circuit. The vehicle's computer monitors all circuits for abnormalities such as no voltage or out of range conditions.
The brake light switch is tied to several circuits, each of which can lead to a dangerous situation. The brake light switch itself consists of two signal outputs, and if the switch is faulty, the problem is detected and this code appears.
This is not a costly failure in terms of parts cost or labor involved in replacement. But for your safety, it is necessary to carry out repairs as soon as possible.
How to Troubleshoot or Reset Trouble Code P0504
Some suggested steps to troubleshoot and fix error code P0504:
Diagnosis and problem solving
The main problem is considered to be a discrepancy between the data in the PCM and the brake pedal sensor. Therefore, let's take a closer look and describe some suggested steps to troubleshoot and fix error code P0504.
The brake light switch is located under the instrument panel at the top of the brake pedal lever. The brake booster raises the pedal to the fully extended position. The brake light switch is mounted on a crossbar support bracket directly behind the brake pedal mounting bracket.
The only way to access the switch is to move the front seat back, lie on the backrest and look up under the dash. You will see a bracket with a switch near the top of the brake pedal lever. The switch will have four or six wires.
The switch rests on the bracket so that its drive rod is in contact with the brake pedal lever when the pedal is fully extended. At this moment, the switch is pressed on the brake pedal lever, cutting off the voltage supply.
When you press the brake pedal, the lever extends to engage the switch and turn on the brake lights. After releasing the pedal, the lever presses the bar again, turning off the brake lights.
Therefore, with a high degree of probability, we can say that replacing this sensor will eliminate problems with error P0504.
How to check
Turn on the ignition and press the brake pedal, the brake lights should light up. After releasing the pedal they should go out. If the lamps do not light up, check the brake pedal sensor and the voltage supply from the battery to the wiring harness block.
(Largus, Vesta, XRAY) Move the rod lock to the right position using a screwdriver. We check the brake pedal sensor using a multimeter in ohmmeter mode. Circuit 3-4 should be closed (resistance value is close to zero), and circuit 1-2 should be open (resistance should tend to infinity). After pressing the rod, circuit 3-4 should open, and circuit 1-2 should close. Before installation, move the rod to the left position.
(Priora, Kalina, Granta, Niva 4x4) Circuit 1-4 should be closed, and circuit 2-3 should be open. After pressing the rod, circuit 2-3 will close, and circuit 1-4 will open.
Thus, the cause of error P0504 may be:
- faulty sensor or its wiring
- Brake pedal sensor is not adjusted
- it is necessary to reprogram the ECM (instruction No. 46-15 for Lada Granta and Kalina 2 with automatic transmission, site users can download it)
To download files you need to log in to the site.
On which cars is this problem most common?
The problem with code P0504 can occur on different machines, but there are always statistics on which brands this error occurs more often. Here is a list of some of them:
With fault code P0504, you can sometimes encounter other errors. The most common ones are: P0016, P0019, P0098, P0121, P0171, P0422, P0432, P0455, P0500, P0571, P0700, P0716, P0732, P0733, P0734, P0746, P0842, P2714, C1241, U040 5.
Hi all! I would like to tell you a little about the M74 ECU and the common error “P0504 Incorrect signal from the brake pedal switches.” In connection with the transition to new toxicity standards, AVTOVAZ engineers and designers have developed a new line of M74 and M17.9.7 ECUs. The ECUs can be said to be normal, but have not yet been fully tested. After all, cars on these ECUs are very much “strangled” by toxicity standards and therefore, without reprog and installing firmware e2 or lower, you can’t drive the car in any way, but this action is not all available now, since the protocol, pads and the reprog algorithm itself have changed with the ECU, in Therefore, it is necessary to have an additional module for the programmer. Diagnostics of ECU data is already available, since all major companies have taken care of their customers and have released software updates.
Well, okay, I’ll start right away with the story of how to get rid of the error “P0504 Incorrect signal from the brake pedal switches.” Due to the fact that the ECUs were changed, AVTOVAZ began installing new sensors and IMs. There are also 2 new sensors on the brake pedal, just don’t be alarmed if you suddenly find only one. AVTOVAZ designers and engineers managed to combine 2 sensors in 1 housing, that is, only one sensor is installed on the brake pedal, but this is not so, inside the housing there is the brake pedal sensor itself and another sensor, which is popularly called “frog”. Error “P0504 Incorrect signal from the brake pedal switches” appears because the sensors are not adjusted properly from the factory. If suddenly a car with M74 or M17.9.7 came to you and the scanner produced such an error, then you can safely take the keys and adjust the sensor gap, since it is not adjusted. The sensor is adjusted in a simple way and is not difficult. There are two nuts on the sensor body. One secures the sensor to the mount from above, and the other from below. The nut that is on top regulates the sensor gap, so loosen the bottom nut a little, and then tighten the top one a little, thereby adjusting the sensor gap. In my case, the sensor was set from the factory so that the button was pressed only halfway, now I made it press almost completely. I say almost due to the fact that I left a small reserve of travel for the button, about 2 mm, so that when the brake pedal is suddenly released, the button does not get too clogged into the sensor. When you adjust the gap, then start the car, having first reset the error, and let it run for a while, since the error is not registered immediately, but after a certain period of 5-10 minutes. If the error is not registered, then you can safely take money from the client and say goodbye to him. Also, on some cars, a clutch pedal sensor is installed; it also needs adjustment, because if it is not adjusted, the car begins to stall, as it were, since the ECU thinks that the clutch pedal is depressed. I guess I'll finish here. If new information appears on the ECU data, I will post it on this forum, since it is the best.
This error often occurs on new cars, since in my opinion our cars are made through... and there is no good quality control department, since cars with such bugs are passed through.
2 years ago AutoTime 0
The power transmission control module (PCM stores error code P0504) when a malfunction is detected in the brake light switch of a VAZ vehicle. A warning light comes on on the dashboard.
When a fault occurs in the brake light circuit, a number of problems can arise. To prevent the vehicle from getting into a dangerous situation, this error will be recorded and the error warning indicator will remain on until the cause is corrected and the code is cleared from the PCM.
Reasons for the error
The causes of error P0504 VAZ are quite simple and easy to diagnose. These include:
Symptoms of error P0504 VAZ
The first sign of an error will be an illuminated “Check Engine” light. In addition, you may notice other symptoms, including:
Diagnosis of error P0504 VAZ
After determining the error code using an OBD-II scanner, it is cleared. All possible causes must be checked. From simple to more complex. You need to start with fuses and light bulbs. If the problem persists, you need to check the brake light switch, wiring, and connectors.
Common diagnostic errors
Often, when the brake light comes on, it is not the driver who assumes that the problem is a burnt out bulb. Replacing the light bulb may not solve the problem, because the source could be the wiring or switch. If the fault is in the switch, then replacing the fuse will do nothing. The new one will also burn out.
How serious is the P0504 code?
It is very dangerous when the brake lights do not work. The car driving behind you cannot correctly assess the situation and your actions, which can lead to an accident. Likewise, if pressing the brake pedal does not disengage the cruise control system, the consequences can be very dire.
What needs to be repaired for error P0504 VAZ?
In most cases, fixing the cause of the P0504 code is quite simple. Here are some of the most typical situations:
During operation of a modern car, defects in engine operation may appear: failures, short-term lack of response of the gas pedal, etc. At the same time, the “Check Engine” icon lights up on the instrument cluster panel, which translated from English sounds like “check the engine.” The car owner goes for diagnostics, where a computer connected to the car detects error P0504. The brake pedal position sensor (frog) is responsible for this failure in the system. Next, we will tell you where the sensor is installed, how to check, repair and replace it.
Error P0504 or problem with the brake pedal sensor
The mileage of the car is 2500 km, and the check is already lighting up with alarming frequency. The pre-installed BC multitronic displays a message that error P0504 is a problem with the brake pedal sensor. I erase it so that it doesn’t become an eyesore, but nevertheless, the error pops up. What to do? How can I adjust/change this button? In the photo this bastard is indicated by a red arrow. As people write, you need to play with adjusting it, which is done with two nuts. The most common thing is that people adjust so that the sensor button barely touches the brake pedal pad. In general, let's give it a spin and see. My BC immediately starts yelling as soon as I start the car, saying there is a mistake. I'll go dig around this weekend.
Thank you!
I noticed that the error pops up more often when you stand on the brake with the selector “D” on. I think the problem is deeper than just adjusting the sensor.
Yesterday, April 14, 2014, I was at the dealer for maintenance. In particular, he voiced hemorrhoids with error P0504. The dealer cheerfully undertook to fix everything. But he didn’t fix it, he said that we need to order a brake sensor, they say it’s defective. I drove out of the gate and wasn’t even surprised when the CHECK light came on again. And this morning the car did not start from the remote control, the BRAKES light was displayed on the key fob, which was corrected by pressing the brake a couple of times, then the car simply did not move, became dull, twitched, but after hitting the brake pedal again, everything was corrected, but then again. In general, the morning did not go well. I freaked out, went to the store and bought this damn sensor.
Here he is, the bastard, in the photo. I went to the dealer, where they changed it for me in 25 minutes without charging a penny. On my part, the cost is 170 rubles for a purchase in a store. So far nothing lights up or jerks. I want to disassemble the removed sensor at home and see what in such a cheap and simple part for 170 rubles was ruining the life of a car worth 450,000 rubles! The truth is, I don’t know how to assemble it, the upper part is on three clips, which are very hard, I wouldn’t want to break it.
I will continue the epic with the sensor. Today, 04/24/2014, Jackie Chan’s new dachik lit up again - P0504. Yesterday I disassembled the old sensor.
What is immediately visible is that the small spring sitting on the rod is crooked. Contacts (nickels) of different heights. In pair 3-2, contact 2 rings in a dull tone, rang with a beeper, if on all the others it beeps loudly and loudly, then on the 2nd it is dull and quiet.
The crooked spring was replaced by another, equal in stiffness, as far as I could determine, and equal in length. I understand that when the brake pedal is released, the rod goes inward and presses the floating contact to the upper group; when you press the pedal, then to the lower one. The scheme couldn't be simpler. However, it doesn't work as it should! the spots were all set up, as if a small welding was working, on one spot there was a mark from the very edge, therefore the floating contact was pressed crookedly. As I understand it, it could have been welded, which sent a signal to the brain that the car was on the brakes.
Everything leads me to the fact that the sensor is made of bullshit! The lower spring is crooked, the terminals are made of poor steel, the spots are made of metal coated with something yellow, which can be removed by sanding with sandpaper. Small spring is crooked. The floating contact does not sit exactly on the patch; it has a slight play. All together will result in unstable work. I put everything back in place, didn’t touch anything, just polished the contacts, started ringing - don’t ring contact 3-2, even if it cracks. And so and so, it seemed to ring. Well, how does this happen? Basically crap. I decided to find a replacement for it, and found this:
the price is almost three times more. For Foltz. Also four contacts, a leg with the same 12mm diameter and thread. I will buy it and make a terminal adapter, from round to flat, like ours.
I don't see any other way. Or from Toyota, Mazda, they also have four contacts on threaded legs, only they are shorter in themselves and a little more expensive. These are the thoughts.
As of May 12, 2014, I can’t do anything. I went on a long business trip, to a place where there is not even a highway, and only KAMAZ trucks pass on the winter road. That’s why my wife left the car, and I drive around there. Therefore, I will try to work on the sensor only when I have rare opportunities to see my family. Good luck to everyone!
Causes and symptoms of malfunction
Most often, error P0504 worries owners of Lada: Grant, Priora, Kalina and other VAZ cars with an ECU. Often a defect appears on GAZ cars, for example, GAZelle NEXT. But owners of foreign cars are less likely to contact the service to eliminate error p0504 and replace the sensor (frog). Most likely, the quality of foreign spare parts is much better. What symptoms indicate that the brake pedal sensor is faulty:
The cause of incorrect operation of the “frog” can be: mechanical damage, oxidation of contacts or wire breakage. Sometimes a failure occurs due to the burnout of both brake light bulbs. Due to the listed defects, an error appears in the system under code p0504. It can be removed, but it will appear again soon.
Error P0504 - the cause is the brake pedal position sensor
Owners of LADA cars with an electronic gas pedal may encounter error P0504 (mismatch of brake pedal sensors). Along with it, malfunctions in the engine may appear (stalls, speed fluctuates, does not start, etc.). Most often the cause is the brake pedal position sensor (brake light sensor or frog).
The brake pedal position sensor and brake light switch are mounted in one housing. Most often, the cause of its malfunction is a broken spring. In this case, you can repair the sensor yourself by replacing the spring with a new one. Or replace the sensor with a new one.
How to change
The sensor is located slightly above the brake pedal lever. To find it, you need to look under the torpedo. On Lada Priora, Grant and Kalina, a 19 mm open-end wrench will be required for dismantling. The replacement process looks like this:
The old sensor is quite repairable. In most cases, the cause of the malfunction is a broken spring. If you disassemble the body and install a new spring, the “frog” will work again.
Car owner's comment: On my Lada Grant, a spring broke in the sensor and began to close the contacts of the limit switches. When I left the car overnight, the ignition did not seem to turn off, which is why the battery ran out completely several times. I bought a new battery, but the problem did not go away until I made diagnostics and replaced the sensor. At the same time, the Check Engine did not light up.
Which one to buy
Experts and service workshop specialists recommend purchasing an original brake sensor. It is of better quality and lasts longer.
Table 1. Price of brake pedal position sensor
| Manufacturer | Code | Cost, rub. |
| AvtoVAZ | 11183720010 | 170 |
| Avar | 2113720 | 180 |
| AMY | 11183720010 | 95 |
Before changing the “frog”, you can “ring” it with a tester to make sure the part is working.
How to Troubleshoot or Reset Trouble Code P0504
Some suggested steps to troubleshoot and fix error code P0504:
Diagnosis and problem solving
The main problem is considered to be a discrepancy between the data in the PCM and the brake pedal sensor. Therefore, let's take a closer look and describe some suggested steps to troubleshoot and fix error code P0504.
The brake light switch is located under the instrument panel at the top of the brake pedal lever. The brake booster raises the pedal to the fully extended position. The brake light switch is mounted on a crossbar support bracket directly behind the brake pedal mounting bracket.
The only way to access the switch is to move the front seat back, lie on the backrest and look up under the dash. You will see a bracket with a switch near the top of the brake pedal lever. The switch will have four or six wires.
The switch rests on the bracket so that its drive rod is in contact with the brake pedal lever when the pedal is fully extended. At this moment, the switch is pressed on the brake pedal lever, cutting off the voltage supply.
When you press the brake pedal, the lever extends to engage the switch and turn on the brake lights. After releasing the pedal, the lever presses the bar again, turning off the brake lights.
Therefore, with a high degree of probability, we can say that replacing this sensor will eliminate problems with error P0504.
On which cars is this problem most common?
The problem with code P0504 can occur on different machines, but there are always statistics on which brands this error occurs more often. Here is a list of some of them:
With fault code P0504, you can sometimes encounter other errors. The most common ones are: P0016, P0019, P0098, P0121, P0171, P0422, P0432, P0455, P0500, P0571, P0700, P0716, P0732, P0733, P0734, P0746, P0842, P2714, C1241, U040 5.
Hi all! I would like to tell you a little about the M74 ECU and the common error “P0504 Incorrect signal from the brake pedal switches.” In connection with the transition to new toxicity standards, AVTOVAZ engineers and designers have developed a new line of M74 and M17.9.7 ECUs. The ECUs can be said to be normal, but have not yet been fully tested. After all, cars on these ECUs are very much “strangled” by toxicity standards and therefore, without reprog and installing firmware e2 or lower, you can’t drive the car in any way, but this action is not all available now, since the protocol, pads and the reprog algorithm itself have changed with the ECU, in Therefore, it is necessary to have an additional module for the programmer. Diagnostics of ECU data is already available, since all major companies have taken care of their customers and have released software updates.
Well, okay, I’ll start right away with the story of how to get rid of the error “P0504 Incorrect signal from the brake pedal switches.” Due to the fact that the ECUs were changed, AVTOVAZ began installing new sensors and IMs. There are also 2 new sensors on the brake pedal, just don’t be alarmed if you suddenly find only one. AVTOVAZ designers and engineers managed to combine 2 sensors in 1 housing, that is, only one sensor is installed on the brake pedal, but this is not so, inside the housing there is the brake pedal sensor itself and another sensor, which is popularly called “frog”. Error “P0504 Incorrect signal from the brake pedal switches” appears because the sensors are not adjusted properly from the factory. If suddenly a car with M74 or M17.9.7 came to you and the scanner produced such an error, then you can safely take the keys and adjust the sensor gap, since it is not adjusted. The sensor is adjusted in a simple way and is not difficult. There are two nuts on the sensor body. One secures the sensor to the mount from above, and the other from below. The nut that is on top regulates the sensor gap, so loosen the bottom nut a little, and then tighten the top one a little, thereby adjusting the sensor gap. In my case, the sensor was set from the factory so that the button was pressed only halfway, now I made it press almost completely. I say almost due to the fact that I left a small reserve of travel for the button, about 2 mm, so that when the brake pedal is suddenly released, the button does not get too clogged into the sensor. When you adjust the gap, then start the car, having first reset the error, and let it run for a while, since the error is not registered immediately, but after a certain period of 5-10 minutes. If the error is not registered, then you can safely take money from the client and say goodbye to him. Also, on some cars, a clutch pedal sensor is installed; it also needs adjustment, because if it is not adjusted, the car begins to stall, as it were, since the ECU thinks that the clutch pedal is depressed. I guess I'll finish here. If new information appears on the ECU data, I will post it on this forum, since it is the best.
This error often occurs on new cars, since in my opinion our cars are made through... and there is no good quality control department, since cars with such bugs are passed through.
2 years ago AutoTime 0
The power transmission control module (PCM stores error code P0504) when a malfunction is detected in the brake light switch of a VAZ vehicle. A warning light comes on on the dashboard.
When a fault occurs in the brake light circuit, a number of problems can arise. To prevent the vehicle from getting into a dangerous situation, this error will be recorded and the error warning indicator will remain on until the cause is corrected and the code is cleared from the PCM.
Reasons for the error
The causes of error P0504 VAZ are quite simple and easy to diagnose. These include:
Symptoms of error P0504 VAZ
The first sign of an error will be an illuminated “Check Engine” light. In addition, you may notice other symptoms, including:
Diagnosis of error P0504 VAZ
After determining the error code using an OBD-II scanner, it is cleared. All possible causes must be checked. From simple to more complex. You need to start with fuses and light bulbs. If the problem persists, you need to check the brake light switch, wiring, and connectors.
Common diagnostic errors
Often, when the brake light comes on, it is not the driver who assumes that the problem is a burnt out bulb. Replacing the light bulb may not solve the problem, because the source could be the wiring or switch. If the fault is in the switch, then replacing the fuse will do nothing. The new one will also burn out.
How serious is the P0504 code?
It is very dangerous when the brake lights do not work. The car driving behind you cannot correctly assess the situation and your actions, which can lead to an accident. Likewise, if pressing the brake pedal does not disengage the cruise control system, the consequences can be very dire.
What needs to be repaired for error P0504 VAZ?
In most cases, fixing the cause of the P0504 code is quite simple. Here are some of the most typical situations:
During operation of a modern car, defects in engine operation may appear: failures, short-term lack of response of the gas pedal, etc. At the same time, the “Check Engine” icon lights up on the instrument cluster panel, which translated from English sounds like “check the engine.” The car owner goes for diagnostics, where a computer connected to the car detects error P0504. The brake pedal position sensor (frog) is responsible for this failure in the system. Next, we will tell you where the sensor is installed, how to check, repair and replace it.
Symptoms and Conditions for DTC P0504 Appearance
The formation of DTC P0504 is caused by the receipt of certain signals into the electronic control unit from the light limit switch , also known as the “frog”. In a number of cars, in particular Lada models with an electronic accelerator pedal, two pairs of contacts are combined in its body: a normally closed one for the brake pedal position and a normally open one for the brake light circuit. When the pedal is pressed, the first contact opens and the second contact closes.
Information about the state of both contacts is sent to the ECU. If their values do not correspond to each other, for example, both contacts are closed or open, or simultaneously with the information about the brake pedal being pressed, the accelerator pedal is pressed, error P0504 occurs .
Since this algorithm ensures safe operation of the vehicle, if the E-gas system malfunctions, if the signals from the brake and accelerator pedal position sensors diverge multiple times, the engine may go into emergency operation mode .
Therefore, together with error code P0504, certain symptoms may appear:
Decoding error P0504 in the diagnostic program
- The brake light lights up constantly or does not light up when the brake pedal is pressed.
- Cruise control does not activate.
- The dynamics deteriorate, the engine speed does not rise above 1250–1500 per minute and/or drops to idle during acceleration, the engine stalls or does not start.
- On cars with automatic transmission, problems with changing the position of the selector may occur.
- The Check Engine light on the dashboard lights up (usually when the error is detected multiple times).
The set of symptoms directly depends on the nature of the malfunction, the logic of the ECU and the design features of a particular model. In some cases, the malfunction may not reveal itself as anything other than an error code in the memory.
Causes and symptoms of malfunction
Most often, error P0504 worries owners of Lada: Grant, Priora, Kalina and other VAZ cars with an ECU. Often a defect appears on GAZ cars, for example, GAZelle NEXT. But owners of foreign cars are less likely to contact the service to eliminate error p0504 and replace the sensor (frog). Most likely, the quality of foreign spare parts is much better. What symptoms indicate that the brake pedal sensor is faulty:
The cause of incorrect operation of the “frog” can be: mechanical damage, oxidation of contacts or wire breakage. Sometimes a failure occurs due to the burnout of both brake light bulbs. Due to the listed defects, an error appears in the system under code p0504. It can be removed, but it will appear again soon.
Reasons for mismatch of brake sensor signals and their elimination
In most cases, error P0504 occurs due to a malfunction of the brake light limit switch or its incorrect adjustment (if required). However, failure is also possible if non-standard lamps are installed in the rear lights. The main reasons for mismatch of brake sensor signals and methods for eliminating them are discussed in the table.
| Causes and solutions to error P0504 | ||
| Faulty element | Reason for failure | How to fix |
| Stop light limit switch (“frog”) | Incorrect adjustment | Adjust the position so that the rod is completely recessed into the body when the pedal is released. |
| Spring is weakened or broken | Replace the spring or change the sensor itself | |
| Contacts are burnt or oxidized | Clean the contact plates with sandpaper or a file, or completely replace the end switch | |
| Brake lamps | Burnt out filament | Replace lamp |
| Installed non-standard lamps with lower resistance, for example, LED | Add a resistor to the circuit, replace with lamps with blende or standard ones | |
| Fuse | Brake light circuit fuse blown | Replace the fuse, if it blows again, check the circuit for short circuit |
| Circuit between limit switch, ECU, brake lights and battery | Broken wires, damaged insulation or contact terminals | Visually check the integrity of the wires and contacts, test the wiring with a tester or test lamp |
| ECU | Damage to contacts, failure of elements on the controller board | Replace contacts and faulty components |
After eliminating the cause of the malfunction, it is necessary to reset error code P0504 using a diagnostic scanner and a special application, otherwise the engine may continue to operate in emergency mode.
How to change
The sensor is located slightly above the brake pedal lever. To find it, you need to look under the torpedo. On Lada Priora, Grant and Kalina, a 19 mm open-end wrench will be required for dismantling. The replacement process looks like this:
The old sensor is quite repairable. In most cases, the cause of the malfunction is a broken spring. If you disassemble the body and install a new spring, the “frog” will work again.
Car owner's comment: On my Lada Grant, a spring broke in the sensor and began to close the contacts of the limit switches. When I left the car overnight, the ignition did not seem to turn off, which is why the battery ran out completely several times. I bought a new battery, but the problem did not go away until I made diagnostics and replaced the sensor. At the same time, the Check Engine did not light up.
Which one to buy
Experts and service workshop specialists recommend purchasing an original brake sensor. It is of better quality and lasts longer.
Table 1. Price of brake pedal position sensor
| Manufacturer | Code | Cost, rub. |
| AvtoVAZ | 11183720010 | 170 |
| Avar | 2113720 | 180 |
| AMY | 11183720010 | 95 |
Before changing the “frog”, you can “ring” it with a tester to make sure the part is working.
