GM electrical guy needed...

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  #1  
Old 05-04-10, 02:13 PM
rebel63's Avatar
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GM electrical guy needed...

'92 Caprice Classic wagon. I was driving along yesterday around dusk and decided to turn on the headlights. When I turned them on, my headlight reminder started "dinging" at me. This is the ding I usually get when I pull into a well lighted area at night and turn the car off before remembering the headlights are on. Well... I was driving at the time, key is in the "on" position and this thing should not be dinging at me!

Today I realized that when I turn the key to the "on" position, I have no idiot lights. It started as usual, but is not charging. It isn't charging, but the idiot light isn't coming on to inform me. I have checked all the fuses. When I put the headlights on, the reminder is dinging like the key is in the off position even though the key is on. AND, just to make it really weird, the gas gauge has gone off the chart... the needle is buried to empty or full, I can't tell~!~!

Anyone have any idea where to start? Can anyone tell me how to get at the ignition switch in this unit? All info is greatly appreciated.
 
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Old 05-04-10, 09:29 PM
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Check grounds located under the dash area or anywhere. I don't off hand where they are located.
 
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Old 05-05-10, 06:34 AM
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Ahhh.... I was hoping someone would come back and say it was a very common problem with these Chevies and I needed a new "what ever".... I just hate "needle in a haystack" electrical problems!
I'll continue my probing but can anyone give me any insight into the R+R of the ignition switch on this Caprice? Is it mounted on the steering column under the dash? Do I have to drop the whole steering column? Any special tool needed? Any info is greatly appreciated.
 
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Old 05-05-10, 07:09 AM
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GM elec

Dont start throwing parts at it,as stated before you have all the symptoms of a bad ground. Maybe someone will chime in that has"been there"
 
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Old 05-05-10, 09:06 AM
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The first thing to do is check the battery and charging voltages...

Check the battery voltage with a multimeter.

A fully charged battery would read 12.65 volts or higher. Use DC volts 20 on the meter.

The battery should read 12 something volts with just the ignition on (not started).

Then start it and it should then read 13/14 volts at the battery. This is the alternator kicking in and charging the battery.

Then measure the voltage inside the vehicle as well. Check from the center of the cigarette lighter to ground and you should get about the same voltage as at the battery. Check with just the ignition on and also with the vehicle running like above.

......

And the reason to check the voltages is that vehicles these days have computer modules and these will not work right if the car voltage is too low or too high.

If that is ok, look in your owner's manual for fuse information. There can be 2 or 3 different fuse boxes. This should say where they are all located.

Be sure to check all fuses. How to test fuses...
Testing fuses Page

Then also check each fuse to body ground with a multimeter to be sure it has voltage. The fuse may be good, but there may be no voltage going to one fuse or an entire fuse block.

If there is no voltage to an entire fuse block, note that some vehicles have "fusible links". With this, the "wire" itself is the fuse!

So find the main wire going to that fuse block and test it to see if it is getting voltage when measured to body ground.

If a wire like that is bad, you would need to order a factory replacement wire which would be the same amperage fusible link or install an inline fuse.

Beyond that, you would need a factory service manual set of books which would have complete wiring diagrams and detailed troubleshooting instructions for this problem.

All the wiring is wrapped up in harnesses, so impossible to trace wires without these books!
 
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Old 05-05-10, 12:03 PM
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Thanks Bill.... the "voltage to ground" at each end of the fuse was the key. Long story short, apparently there are cascaded fuses in this GM system, that is, one fuse after another. When the big dog goes, the rest are dead also.

Visual inspection did not detect a blown 15 amp fuse. Checking voltage at both ends with the voltmeter revealed the problem. Replaced the fuse and all the other totally dead fuse circuits came back to life.

It never fails to amaze me that we can forget the simplest measures to ensure accurate testing of parts. At a minimum, I should have put an ohm meter across each fuse as I pulled it out to inspect it visually. Using a 12v test light on each end of a fuse is just about fail-safe too. Just gotta make sure the key is on to feed voltage to the fuse box!!!

Thanks!
 
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Old 05-05-10, 12:10 PM
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thanks "retired wrench".... I was just asking about the ignition switch info, I NEVER throw parts at any job, LOL! I'm WAY too damn cheap to do that!!! If I could get at that switch easy enough, I would have just tested.... tested, tested, tested.....
 
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