Electrical Issue, Ground Locations
01-17-12, 09:59 PM
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Electrical Issue, Ground Locations
Hi, first time posting in the technical section, I'll try to be brief.
Car is an 81' GSL M/T, Stock, 124k miles.
Previously (about a month ago) I noticed that with the heat, radio, lights and brake lights on, the tachometer would jump around a bit, (1000rpms) when Idling.
I've been meaning to adjust my idle since my lights dim and I lose a volt or so below 900rpms. This stopped after about two days.
Today when I took the car out all hell broke loose after about 20 minutes of driving. Stop lamp/add coolant lights, tachometer bouncing all over the place, lights dimming, radio cutting out, everything.
This was only with the car idling coming up to a stop. Headlight motors brought the battery down to 10 volts with no other accessories active.
Also, before everything went nuts, switching between high/low beams caused the radio to cut out for about a third of a second. Radio positive is wired straight w/ a fused wire, ground is stock, switched pos. is running an add-a-circuit on a ten amp location. I lost my fusebox cover and have forgotten which it is
Are there any common grounds that could be corroded and cause this?
I had the EXACT same symptoms with my 92 saturn, alternator (load tested thrice) and grounds were good, and nobody could figure out what is wrong with it. (I'm terrible with automotive electrical systems) I am posting before I pull the alternator because the garage the car is in is heated, but only to about ~10 F.
Any advice would be appreciated, thanks.
Car is an 81' GSL M/T, Stock, 124k miles.
Previously (about a month ago) I noticed that with the heat, radio, lights and brake lights on, the tachometer would jump around a bit, (1000rpms) when Idling.
I've been meaning to adjust my idle since my lights dim and I lose a volt or so below 900rpms. This stopped after about two days.
Today when I took the car out all hell broke loose after about 20 minutes of driving. Stop lamp/add coolant lights, tachometer bouncing all over the place, lights dimming, radio cutting out, everything.
This was only with the car idling coming up to a stop. Headlight motors brought the battery down to 10 volts with no other accessories active.
Also, before everything went nuts, switching between high/low beams caused the radio to cut out for about a third of a second. Radio positive is wired straight w/ a fused wire, ground is stock, switched pos. is running an add-a-circuit on a ten amp location. I lost my fusebox cover and have forgotten which it is
Are there any common grounds that could be corroded and cause this?
I had the EXACT same symptoms with my 92 saturn, alternator (load tested thrice) and grounds were good, and nobody could figure out what is wrong with it. (I'm terrible with automotive electrical systems) I am posting before I pull the alternator because the garage the car is in is heated, but only to about ~10 F.
Any advice would be appreciated, thanks.
01-18-12, 06:45 PM
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I personally would pull a fuse, check to see if the symptoms continue. If it does, replace the fuse and try another. If the symptons don't continue, then the problem is somewhere in that circuit.
01-20-12, 01:59 PM
#4
What you're describing is most likely an alternator problem. You can test the alternator per the 1st gen FSM by probing the R and L pins on the back side.
Key off: 0v at both the R and L terminals (measured separately)
Key on: 1-3v at the L terminal
You can also take the alternator to an auto parts store to have it load tested.
1st gen FSM: http://www.rotaryheads.com/PDF/1st_g...Electrical.pdf
Key off: 0v at both the R and L terminals (measured separately)
Key on: 1-3v at the L terminal
You can also take the alternator to an auto parts store to have it load tested.
1st gen FSM: http://www.rotaryheads.com/PDF/1st_g...Electrical.pdf
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