Grrrrounds

[pullmyefinger]

85 GMC S15, 2.8, 4 speed, 6 cyl manual tranny.

Gauges are going crazy. I was reading in another forum about ground straps causing havoc with electrical systems and that is what it is doing.

Specifically:

lights on the dash panel and headlights flicker on and off now.

recently installed a relay with a temperature sensor connected to an electric fan. I was told the engine wasn't getting up to operating temperature and that is not good. gas mileage stinks for one thing, and it's a stick shift that should be getting 15+ around town according to the EPA estimates.

fan used to run constantly, now it is supposed to run only when the engine temp sensor tells it to.

now, alternator gauge starts ok and gives me 15-16 volts, oil pressure gauge is ok and temp gauge is ok when in fast idle for 4 minutes (even in the middle of august it goes into fast ide or it runs like crap).

Once I put it in gear the gauges go stupid, even though the alternator was rebuilt a month ago and puts out 14.7v on the charging line. Belts are fine and do not slip or squeal. Battery is ok at about 12.6v at rest. We fixed a radiator leak recently too.

The alternator gauge starts to drop down when I put the truck in reverse or any other gear. The lower the alternator gauge goes the higher the engine temp gauge goes forcing me to stop and shut it off. I turn it back on almost immediately and the gauges go back to normal, then the same old crap starts. The relay/temp sensor/electric fan stuff comes on and cools the engine down. This all happens within 5 miles driving. It used to also make the radio/cd player beep and reset along with the fasten seat belts light coming on, but the truck still ran fine. Oil is clear, recently changed and does not look like a milkshake.

I cleaned, wire brushed and put dielectric grease on all the grounds I know of, even the dash gauge ground by the emergency brake. No difference.

There are two wires bolted to what seems to be the bell housing bolt that are fried.

IS THIS AN ENGINE GROUND?? There is another ground that connects to the firewall in the middle that grounds the blower motor and the relay and that Seems OK. We added an extra ground to the frame for the headlights and the battery; that one might need cleaned up again even though it seems tight.

We also removed the dash panel and an electrician checked all the copper tracings and said they were ok.

What I want to know is Where are all the grounds supposed to be on this vehicle? Where do they connect, starting and ending? What else might be causing this mess?? I don't know enough to do everything and am getting tired of not being able to drive the truck for fear of the wiring harness burning up and God knows what else... Any help would be appreciated, even links to other sources cuz my Haynes manual probably isn't specific enough.