An electrical circuit needs a good ground to function properly. Many people ask - why is engine demining necessary? The answer is - poor electrical grounding can affect one or more electrical systems, because it forces the current to look for other simpler paths. This can cause all sorts of problems with lights, sensors, modules and other electrical and electronic components, all of the above is also true to answer the common question - what is the purpose of mass in a car.
Causes and symptoms of poor engine grounding
Engine malfunction may be caused by:
- Loose, rusty, or damaged ground terminals or wires
- Weak, damaged or corroded battery ground terminal
- Poorly installed or repaired components
Symptoms of a poor motor ground may include:
- Dim lights
- Flickering lights
- Electrical devices operate erratically
- Faulty fuel pump
- A slipping or burnt A/C compressor clutch
- Intermittent sensor failure
- Throttle or transmission cables are damaged
- Hard start
- Low battery
Often bad grounds are relatively easy to diagnose and correct, usually in a matter of minutes. You can diagnose and repair in your own garage using just a digital multimeter (DMM) and some common tools.
If you don't know where all the engines or transmissions are located in your vehicle, you may want to consult your vehicle's repair manual. You can get a relatively inexpensive copy through Amazon. Haynes manuals come with step-by-step procedures for many maintenance, repair and troubleshooting projects. This way, you will recoup your small investment in a short time.
FINE. So grab your multimeter and let's find those bad grounds in your car.
Corrosion or damage to grounding straps can cause electrical accessories to malfunction.
Instead of an afterword
Afterwards you will find out the actual mileage, number of owners, history of fines, as well as information about theft, participation in an accident, restrictions on car registration and much more. Be carefull!
Having fully studied the online report, it is still worth taking a closer look at the technical nuances of the car when purchasing. And if you are not confident in your knowledge, or it is not possible to go for an inspection, order an on-site inspection service. The specialist will conduct a diagnosis for you and make a detailed conclusion from a professional point of view.
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Electrical ground diagnostics
The following sections are divided between tests. This will make it easier to test the starter and accessory ground paths to identify common electrical system problems.
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Here are some important points to keep in mind when troubleshooting your car:
- When testing, make sure the terminals are attached to an unpainted surface. You have to connect to bare metal. Paint, corrosion, greasy surfaces, frayed or broken wires, and loose connections are the main causes of poor automotive finishes.
- Some vehicles use a separate chassis ground wire in addition to the main one (black battery cable) that runs from the negative battery terminal to the chassis. This is for headlights, accessories and other electronic equipment.
You can use the remote starter switch to crank the engine while testing your vehicle. Connect the switch to the battery and the "s" terminal on the starter solenoid or remote starter relay.
What is this device and how does it work?
Its name says it all - switch. The simplest models will cost 2-3 hundred rubles. The ground switch is installed in the gap between ground and the negative current terminal of the battery. If other current consumers are directly connected to the battery, then the switch breaks their ground as well. Typically, such a device is implemented directly on the negative current terminal of the battery. They differ only in the way the line break is implemented.
Often such switches are made in the form of a button, a flag switch, or even a screw clamp. All these mechanical type models perform circuit breaking and joining. When the circuit is closed and opened, the contacts may burn. Because of this, transition resistance arises, which leads to a deterioration in the electrical characteristics of the on-board vehicle network. Therefore, normal devices have forecontacts that take the brunt of connection and disconnection.
There are more advanced remote battery disconnect switches. These are electromagnetic switches that can be installed in the engine compartment and controlled from the passenger compartment. The button or switch is installed somewhere in a hidden place. Cost from one to several thousand rubles.
And one moment. Why is the wire broken from the negative current terminal of the battery, and not the positive one? Just to avoid accidentally shorting something to a “broken plus”.
Why is mass needed in a car?
Grounding the engine provides an electrical return path for the starter. Poor engine grounding is a common problem resulting in hard starting and no starting.
The following test takes a voltage drop reading to determine any unwanted resistance in the motor ground circuit.
- Disconnect the ignition or fuel system to prevent engine starting during testing.
If the ignition system has a distributor, you can disconnect the high voltage cable from the distributor cap and ground it to the engine (bolt or bracket) using a jumper wire. On other systems, you may be able to remove the fuel pump fuse. Consult your vehicle's owner's manual or vehicle repair manual to locate the fuse. You can also use a remote starter switch. Connect the switch to the starter relay or solenoid (selector relay) control circuit terminals.
- Set the DMM to a constant voltage and select a range as close as possible but greater than the battery voltage. For example, 20 volts. Or select the auto-ranging feature, depending on your multimeter's features.
- Connect the red meter lead to a clean surface of the engine and the black meter lead to the negative (-) terminal of the battery.
- Have a helper run the engine for about five seconds, this is enough to get a good current reading.
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You should get a reading of 0.2 volts or less. If necessary, refer to your manufacturer's specifications in your vehicle's repair manual. Did you get a higher reading? There is unwanted resistance in the ground circuit. To find the problem, proceed to the following steps.
- Move the red lead of your meter to the main ground terminal on the engine side.
- Have a helper crank the engine while you take a voltage drop reading.
Repeat the previous two steps, moving the red wire to the connector connecting the black main ground wire to the battery terminal. When you get a reading around 0.2V or lower, the unwanted resistance is between this and the previous test point. Check for corrosion, broken or loose wires.
Solutions to the problem
If power outages occur frequently or current leakage occurs during long periods of parking, you can improve the system to solve the problem. It’s not difficult to get the job done; the minimum set of tools that every motorist should have is enough. The procedure depends on the nature of the malfunction.
How to make mass better
If removing and cleaning the contacts does not produce any effect, you will have to use more radical repair methods. In some models, the problem with a minus on the body is a real “disease”, so it is necessary to improve the design in order to eliminate the manufacturer’s shortcomings:
- Replacing the wire. Most often this concerns the “braid” from the battery to the engine, since over time it becomes damaged or becomes heavily oxidized. It may also be necessary to install a core on the body with a large cross-section or the same one if it is damaged inside and does not pass current as necessary.
- Changing the mounting location on the body. Sometimes the stud for the nut literally bends out or the factory connection point does not make good contact. In this case, the easiest way is to find another place and secure the terminal there.
- Adding additional mass. Another option that will improve the system without much modification. Particularly well suited for older models and cars in which it is very difficult to get to the standard mount.
It is necessary to monitor the condition of the wires and replace them if there is even the slightest doubt about reliability. It is best to use the same elements as those installed, plus high-quality fasteners.
Installing the mains switch
The switch will protect the car from current leakage, short circuit, and can also serve as an additional anti-theft system. It’s easy to install it yourself; most often, one of two options is used:
- Manual switch. Placed under the hood in a suitable place. A more convenient solution is a special version combined with the battery terminal. It should be located between the battery and the ground wires of the engine and body.
- Remote option. In this case, the shutdown button is displayed in the interior; it is usually hidden so that no one else can start the car. The principle is the same, but installation is more complicated, since you need to run the wires into the interior.
The switch is not suitable for cars with an alarm and central locking, since if there is no ground, the system will not work. It is also undesirable to install it on models with a lot of electronics.
It is not difficult to locate the ground wires; they should be periodically removed and processed to ensure good contact. When checking, it is better to use a multimeter, this is the easiest way to detect damage if it is present. It is recommended to replace worn wires in a timely manner, and to prevent leaks, you can install a power switch button.
Checking grounding in a car
Electronic modules and many electrical components in the engine, transmission and passenger compartment use the body as an electrical ground. This test checks for unwanted resistance at these points, including the secondary ground between the battery and chassis used by some older models. If necessary, consult your vehicle's repair manual.
- Connect the black lead of your meter to the battery (-) terminal and the red lead of your meter to where the wire connects to the body.
- Have a helper crank the engine for a few seconds.
You should get a voltage drop of 0.2V or less. If the voltage drop is higher, proceed to the next steps.
- Move the red lead of your meter to the terminal on the end of the secondary ground wire. Take voltage drop readings.
If you get a reading higher than 0.2 volts, proceed to the next step.
- Move your meter's red test lead to the next terminal and ground point. Take voltage drop readings at each point.
When you get a reading around 0.2V or lower, the unwanted resistance is between this and the previous test point. Check for corrosion, broken or loose wires.
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Also, check the voltage drop on the ground circuits that connect the engine to the chassis.
Search, check and replace transfer grounds if necessary.
Checking weight in a car
Transmissions on some vehicle models are equipped with a chassis or protective shield for modules, sensors, and solenoids (relays). You can also test these grounds using your digital multimeter.
- Check the voltage drop between the transmission and the negative terminal of the battery. The voltage drop should be 0.2V or lower.
- Check individual chassis grounding by checking the voltage drop across each ground terminal on the transmission. The voltage drop should be 0.2V or lower.
Clean, repair or replace the transmission ground as necessary. Remove grease, rust and paint from ground terminals or replace damaged ground straps.
General Voltage Drop Values
Choke cables and other equipment can be damaged when high electrical current cannot find the correct path back to ground.
