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MrPants's Avatar
 
Join Date: Mar 2003
Location: dfw, texas
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are these electrical problems diagnosable?

i have a ton of screwy electrical issues and i am at the end of my ability to diagnose them.
1) headlights come up and turn on fine, but do not go down. occaisnally (like perhaps once a week) i will go outside and they will be mysteriously down. i assume this is do to elves of some sort. i cleaned the relay. is there a way to test if its good?
2) wipers: were working it just appeared to be another bad relay: they would function but would stop where ever they were when i turn the switch off. i replaced the relay with a used one i found and now they dont work at all. they twitched twice today while the switch was off
3) instrument lights do not work. replaced fuse 12. no change
4) no tail lights. have brake and back up lights but no tail lights
5) oil pressure gauge ticks down exactly one bar with each tick of the clock's second hand.
6) last week i had problems with the car not starting, it acted exactly as if tghe battery was dead: cranking for a few seconds and then kind of puttering out before the engine could catch. the battery read 12.2 volts but it would not start with out a jump. this is no longer a problem but perhaps it will give someone a clue.
maybe a bad ground? i dont know what makes a ground bad exactly. i looked at the on near the battery, on the block, and near each headlight and none are corroded and they are too tight for me to wiggle so it seems like they are ok.

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Old 07-09-2003, 03:52 PM
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You need to physically break the ground connections (remove the bolt) and clean the terminal lugs. TarnX works, but be sure to rinse with water.

For the "hard points" use either a wire brush or some fine (320 or higher) grit sand paper.

While you have the grounds disconnected, give them a good visual inspection, looking for cuts, cracks, worn insulation, broken strands, etc. While you're at it, make sure the battery terminals and cables are clean and tight. Same goes for the connections to the starter and alternator. Checking the starter connections is kind of critical because the starter is also used as the main tie point for the positive side of the electrical system.

For your head lights and wipers, there are switch contacts in the gear housings that control when the motors run. For example, the wipers will stop when the key is turned off (with the wipers on), and the wipers will automatically park if you turn the wipers off and then turn the key on. The head light motor is similar with the exception that the relay controls the motor, and the contacts in the gear head "tell" the relay if the lights are up or down.

Some of your other problems may be caused by a flaky ignition switch.

Do you have ANY dash lights at all? If not the problem could be the dimmer rheostat in the light switch.
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Old 07-09-2003, 04:32 PM
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ill clean grounds tomorrow
i do indeed have no dash lights. ill see if anything in the dimmer switch looks odd
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Old 07-09-2003, 11:07 PM
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sounds like a classic case of oxidation on grounds. I use 400 grit sandpaper on spade lugs and contact surfaces. there about 6 main chassis grounds depending on year. Mainly- behing the headlight buckets, the intake manifold ground and rear underneath the carpet inbetween the taillights under the hatch. make sure to disconnect the battery negative, sometimes you can blow a fuse, relay or even worse the DME itself.

My wiper connector jiggled loose- look near the wiper motor behind the firewall.

I had BOTH bulbs burn out simultaneously. was really weird. check the bulbs. I traced wires for days then looked at the bulbs. doh.

Clean off the battery terminals and connectors with a battery tool (kinda like a 2-way round stiff wire brush. I got mine at autozone for 5 bucks many many moons ago- it's always in my toolkit.

I thought NA was "Naturally Asthmatic!" Good luck!
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Old 07-10-2003, 06:08 AM
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ok i cleaned 3 of the grounds and the battery terminals today before it got dark. now the headlights dont work at all and the sunroof is stuck open. any ideas!!!? if the problems dont let up soon im worried im gonna have to get rid of it.
ps do i have to take the steering wheel off in order to get to the dash lights?
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Old 07-11-2003, 07:33 PM
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You can wiggle the speedo out after you feed the speedo cable up as far as it can go.

I took my wheel off to work on mine- pull the horn pad off, and the wheel comes off with a deep 23mm (i believe)socket . just mark the wheel location on the column. (I use a white grease pencil)- wheel comes right off.
remove the 2 screws on the panel and it comes right out.
Check out www.clarks-garage.com early dash removal. It's all there.

seeing as you have NO lights I suspect the light switch on the dash may be bad as well. Pull the switch and remove it- inspect the contacts and replace with a known good test switch.

good luck- Chris
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Old 07-11-2003, 10:43 PM
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Quote:
Originally posted by yo mama
ok i cleaned 3 of the grounds and the battery terminals today before it got dark. now the headlights dont work at all and the sunroof is stuck open. any ideas!!!? if the problems dont let up soon im worried im gonna have to get rid of it.
ps do i have to take the steering wheel off in order to get to the dash lights?
If you've got a multi-meter you might want to check the resistance of the main ground wire. If you don't have a multi-meter, go buy one as it's a great tool to always have access to($50 or more/less at a Sears). Check the resistance of the ground wire, between where it bolts on to the body and the negative terminal on the battery. Allthough this wire can look good, it can still be bad. I had nearly 5ohms of resistance between the bolt and the battery terminal. I replaced it with a 12" length of 4g, and now measure 0.0ohms of resistance.


I'm still in the process of 'beefing up' other grounds in the car. I used to have an oil pressure gauge that read from 0bar to 2bar depending on driving conditions, fixed ground and the lowest it reads now at hot idle is 2bar, cold idle between 4-5bar. The grounds on the oil pressure gauge read close to 14ohms between the battery and gauge, it now reads 0.1ohms.
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Old 07-12-2003, 08:16 AM
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you may as well pull the steering wheel because the wiper/washer and signal/headlight switches on the steering column probably needs a good cleaning too

http://www.************************/ProductPage.aspx?ProductName=Electrifix&productid=102177&producttype=10

for a cool set of tools to do this with…then of course

http://fsjeep.homestead.com/files/TFI_Upgrade/dielectric_grease.jpg

available at almost all auto parts shops
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Old 07-12-2003, 08:19 AM
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perhaps someone with electrical knowledge can help me out.
is it possible for there to be something drawing power? like some crossed wires or something? such that only those components closest to the power source are getting power?
i also just realized that all my headlight and dash light problems could be related to a bad switch. im gonna pick one up when i get the belts retensioned next week.
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Old 07-13-2003, 11:51 PM
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Yo Mama, where you at in DFW?
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Old 07-14-2003, 12:06 AM
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sort of caddy corner to you. in denton.
i just applied for a PCA membership though, i think we are in the same region if you are a member
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Old 07-14-2003, 12:15 AM
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Not a member,but wanna be,My father is,Maverick Region, is what I would be.
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Texas hosts the 928 Owner’s Club OCIC in 2009
www.928ocicdfw09.com
1980 928 5 speed and a few mods..........
928 OC member
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Old 07-14-2003, 12:35 AM
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Quote:
Originally posted by yo mama
perhaps someone with electrical knowledge can help me out.
is it possible for there to be something drawing power? like some crossed wires or something? such that only those components closest to the power source are getting power?
i also just realized that all my headlight and dash light problems could be related to a bad switch. im gonna pick one up when i get the belts retensioned next week.

Yes, you can put an Amp meter in line & start unplugging until you get whatever is drawing current.

drew1

Old 07-14-2003, 05:53 AM
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