How can you find a bad ground wire in a vehicle? How to diagnose automotive electrical ground issues, and what to do if you don't have a good engine ground.

The kind of frustration that makes young men old and old men talk to themselves can be achieved by chasing down electrical gremlins in a motor vehicle.

A bad ground connection is often the cause of an electrical problem.A bad ground can cause noise in an audio system, make electric fuel pumps run hot or produce low pressure, and make electronic engine controls weird.

Many think that the accessory is grounded if the ground wire touches some part of the vehicle.That isn't the case.The ground wire needs to be attached at a point that is free of paint, rust, or plated.A bad ground connection can be caused by paint on body panels and the engine.

To make sure there is no paint between the starter and the engine block mounting surface, it is best to run a ground wire directly to the alternator case.

After you redo the grounds, you will need a multimeter to trace the wiring of your accessory.The battery's negative stud and ground connection on the accessory should be probed by the voltmeter.The ground is okay if you have a reading of less than five.

If the resistance is okay but the accessory isn't working right, set the voltmeter to DC current.Take the accessory off and retrace the path you took before.The load should cause the voltage to be no greater than.05 volts.If you find a point where voltage is present, you need to add a bonding strap or locate a new point so no voltages are present.

The grounding path between the accessory and the battery needs to be probed if the reading is higher.Start at the battery and run the probe from there to the first point of contact.Continue to where the fender connects to the main body.Attach a bonding strap or wire between the panels or parts where resistance is highest if you find a point of high resistance.

Adding an engine-to-chassis ground strap is one of the best things you can do to ensure a properly grounded vehicle.

The battery-to-chassis ground should be replaced with a larger gauge wire if you are adding accessories that draw a lot of current.The factory ground wire is usually 10 or 12 gauge.The positive or supply wire to the battery must be as large as the ground wire.

Hopefully you won't have to experience the joy of tracing a bad ground.If you find yourself in this situation, these tips will help you get your ride back on the ground.

Eric the Car Guy has a two-part video series on the basics of automotive electrical problems.

Without being grounded to the vehicle or the engine, your electrical stuff won't work.You can use your audio system as an example.A common ground wire is the best way to ground a system.The negative side of the battery is a good place to put that wire.It's important to make sure the grounding point is free of paint, rust, or plated, which can prevent a good ground connection.

If your accessories draw a lot of current, replace the battery-to-chassis ground with a large gauge wire or strap like this Taylor Diamondback braided ground strap.The engine block can be grounded with the strap.If the stock strap is damaged, it's a good idea to replace it; many vehicles had an engine to ground strap from the factory.

It's important that the ground is good for engines that are electronically fuel-injected or have some other type of computer control.The ground connections in the Aftermarket wiring harnesses make it easy to ground them.Painless Performance also has complete vehicle harnesses for muscle cars, street rods, and race cars.Don't use a test light to check components.The components will be destroyed by a test light that is inaccurate.It's better to use a good multimeter.

The Sunpro Auto TroubleShooter is indispensible if you work on electrical systems often.It can be used to locate faulty wiring, test electrical components, engine sensors, ignition and fuel systems and starting/charging system voltage.Here is a sample of what the multimeter can check.

The Actron AutoAnalyzer multimeter does the same testing as the Sunpro Auto Troubleshooter, but costs less.All standard electrical tests are performed by it.It has a backlit LCD for easy reading, color-coded test leads, and alligator clips for hands-free test lead connections.

Hey Dave, I have a question.I have never dealt with the electrical side of automotive.I got a multimeter to figure out my problem.It is hard to find a trustworthy mechanic who knows jeeps or an affordable diagnostics scanner, and that works with my 2005/06 Wh/Wk jeep grand Cherokee.I don't have the money to fix the problem without throwing money at it.I have been driving for 2 years with lights on the dash.There was a park brake light on the dash.The battery, front hubs, and all the WSS sensors have been done.It is stuck in limp mode with the e-brake light on the dash.I am waiting on a pair of shoes.50% front and 70% back are waiting for the pads.I am trying to figure out if the pressure switch is + or - but I can't find a diagram or answer online.Is there no power to the e-brake wire?Is it a good idea to have power til grounded?Is the circuit broken by the brake pressure switch?I thought the fluid level wire had power.The brake booster switch can't be turned on to test.Any information would be appreciated.

I ran across this.I had a dead battery and a new one put in.When I turn my headlights on, it dims the panel inside the car but it's still bright.I had the new battery checked and they both read good.I am off social security.Is it possible to make recommendations?The shop said my two wires were tight.I own a mazda 3.

I am an electrical that works on cars and has been for the past few years.There is a short answer.Who knows?If you don't want to do it yourself, there are specialists who can.Do you want to do it?Is the battery strong or weak?Check the specifications of what you have.Money is spent time.I would take the alternator to the shop.There is another shop for a second opinion.

I had a Mercedes C Class that died while I was driving last weekend.The warning signals came up when the lights on the dash came on.The techni guy said it was too dangerous to drive.They told me that it had had a catastrophic failure and it would take them some time to figure out what caused it to stop running.They called me back and said that they thought it wasn't earthed properly.He said that he was assuming it was that.They think it's fixed up, but they can't guarantee it wont happen again, so I have to drive down the highway again.Does this sound like a car that has not been earthed properly before?Hope you have an idea.

I am trying to fix a 2005 e320 that throws obd fault codes.The same fault reappears after I replaced a few of the sensors.All the sensors have the same battery voltage and ground.The ground strap was found near the body.I think this is part of the problem.Before I install a new ground strap from the dealer, I need to know if it has any anti-seize or grease that will retard future corrosion.Will this affect the quality of the ground connection?

It's a good idea to use a dielectric grease.It is possible for an electrical connection to be tight but not tight.

I own a 97 ford f 150 with a 4.6 in it.I think I have a problem.The dome light goes off when I open the door.This can happen with the truck on or off.Any ideas?

The first thing I would do is check the body grounds.There should be a wire that bolts to the fender.Remove the bolt from the fender and sand the area, then replace the wire with grease on the contact surface.I would get 10awg wire, a couple ring terminals, and add it to that body ground.The truck is 23 years old and the battery cables have not been replaced.They go bad after a while.The wire and ring terminals will be less than 20usd.It has a good chance of clearing up electrical issues.

Something as simple as paint getting in the way can cause an electrical interruption in a car.I have only started driving my new car six months ago and it's my first time driving an automatic transmission car so it is difficult for me to fix electrical problems.I want to find an automotive repair service near me this weekend so that I can figure out what is going on with my car.

I ran a code test at the auto zone and only one code U1300 class 2 was short to ground.How do I fix this?What should I do next?

I have a malibu maxx that blows the power window 30 Amps and it is located in the cabin pass seat side fuse box.It only blows when I start the car, or if I put a fuse on the box.If I just turn the key to the on position, the windows and switches won't blow, only when the car is running or started.I have been trying to examine cables and the engine looks brand new, but the previous owner may have changed it.

Engine not running as I work on my old sentra eccs.When the engine runs, the battery terminal voltage at the posts can be as low as zero and as high as 14.7%.This is the first time I have encountered such a problem.All the connections were removed and the battery was the only thing running.Same results, used two dvms.Is this a grounded issue?All ground points were cleaned and checked.Since the engine doesn't run that long, it's hard to trace it.

The land rover defender blower motor was not working when I put a multimeter on the ground and live wire at the load side.There is good continuity between the earth terminal and the blower.

This section is very useful from what I have read.When I drive a BMW e90 325i, it just goes off and doesn't start until after a while, the battery might be full, but then I'll have to wait for some while before it responds and starts again.I don't know what the issue is and I'm confused about it.Sometimes it stops on full traffic when I am going over 100 mph.

I have an issue with my yamha quad.I have power when the key is on and the light is connected to the frame.The starter and starter have power.

How is the battery?It is possible that your battery has enough juice to power a tiny test light but not enough to turn an engine on.I have had that happen when working on old motorcycles.When I come back, there is not enough current to turn over the engine, so I will leave the power on.

I have a 2003 Chevy Avalanche that has a check engine light that says evap vent Solenoid has tested it and it is all good, but no ground tried it with the car running and not running.When the light goes off, I am pretty good at this stuff, but the computer doesn't like throwing parts in things I know it has a positive ground system.

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