Possible Ground Problem???

[SleepIsTheCuzinOf]

I have a '93 Mark and I've come across a problem

well... let me start off the thread letting you all know that I'm not a seasoned mechanic or electrician, but I'm not afraid to get my hands dirty. My father is better with cars but is computer illiterate.

well, this all started last week when my car was broken into and the stereo was taken.. $300 later I had a window and stereo...

after the stereo was installed (by best buy) the little charging system light started showing up and the speakers were picking up noise from the electronic system any change in voltage especially when the air compressor kicks on when the unit is off or the faceplate is removed,

which led me to believe that the alternator is going out..

BUT the noise is apparent with the key turned to on/accessory without the engine running (though it isn't as loud as it is when the engine is running)..

Well, today I was searching under the hood and noticed the idler pulley had seized... I replaced that thinking that maybe had caused the problem... at first the light did go off and the noise was barely apparent, but has since returned...

I tested the alternator at about 13.5 volts at idle and the same at 3500 RPMs.. that seems fine to me..

I had a conversation over the phone with the owner of a local electical shop and he said he believes it may be a ground problem and it will run me $77 bucks an hour for him to take a look...

I can't afford to do so, but I also cant run the risk of frying my electrical system...

I've checked and cleaned the battery terminals, I have checked the ground connection... checked every damn fuse in the car and also the connections to the fuses... again I'm a car novice so I am at a loss.. I don't know much about electrical systems other than knowledge of complete circuitry, etc.

but I have no idea where to start looking for a ground problem, if i had the money i'd gladly pay the electrical shop...

 

[driller]

Start with a basic charging system test.

1. Engine off - battery standing voltage.
With the engine off and fully charged battery, hook up the meter directly to the battery terminals(not clamp, bolt, nut, etc...). Read the meter as volts DC.

2. Engine running - lo idle - no load charging voltage.
Engine running at idle, all lights, accessories and AC off. Read the meter after voltage stabilizes from starting engine. Should be higher than standing voltage.

3. Engine running - hi idle - no load charging voltage.
Engine running at 1500 RPM, all lights, accessories and AC off. Read the meter. SHOULD BE NO MORE THAN 2 VOLTS OVER STANDING VOLTAGE.

4. Engine running - full load charging voltage.
Engine running at 2000 RPM, lights on high beams, AC on MAX(blower on high). Read the meter. Will be lower than hi idle no load charging voltage but should be higher than lo idle - no load charging voltage.

Sounds like you may have a ground loop issue with the stereo install. Check that the ground for the stereo is connected to a good ground source.

 

[Sierra3]

Yes

Yes

I aggree with Driller. Do his voltage tests first. Then go for the ground issue after that. If you had an amp installed along with stereo check its ground also for a good ground. Also where they grounded your radio. If they used a proper pinout adapter for install of new radio youre all set, but if they "picked" a new ground for it or the remote power lead for the amp. They might not be the best locations.

Also, off topic, but you do have a wiring harness for the air ride that runs horizontal across the back seat on inside of trunk. Make sure the installer didnt run a sheet metal screw though the harness installing your amp back in. As was the case with me and Circuit City. Had to fix the whole stinking harness with solder and heat shrinking. If youre getting noise id say its more of a bad ground issue or poor placement of ground area.:wink: