grounding issues/weird science?

[dougk]

Has anyone ever experienced a quick on-off of the headlights when pulling on the hood release lever under the steering column (with all systems off from the night before)??? It happened to me while attempting to check under the hood to research an idle boost problem that occurs regularly in my '86 that has 34K miles: seems when I drive the car first thing in the morning, everything functions normally, but if I stop the motor and start up after that, the idle would sometimes jump to about 2K and stay there until the next time I stopped the car and restarted it...I changed the idle air controller which briefly seemed to solve the problem, but then after some more thought, I considered the possibility that I might be getting a charge buildup (as evidenced by the headlight flash?), so I cleaned off several of the grounds, mainly the braided one on the firewall behind the engine, and all seems to be working better: even my regular idle has dropped to around 900 from 1000 - 1100 rpm. Right now I've got my fingers crossed that my issues were of an electrical grounding nature, but I would be interested in hearing from anyone who has had similar problems, and what cures you've discovered. Thanks.

[Eyelawdoc]

Ball Lightning?

Even though your 86 has only 34K miles, it is 18 years old and many of the electrical issues that plague these cars seem as much age based as mileage influenced. Terminal corrosion, especially in a car that isn't driven a lot, can be a problem.

Grounding is very critical with these cars. You might also want to perform the TPS setting procedure outlined in the FAQ section. The symptoms you are describing with the idle speed indicate that one of the sensors is intermittently dropping out causing the EEC to go into limp mode. As Mike Flemming has explained many times, when you shut the key off it pruges the EEC of it's short term memory and it resets back to normal operations until the sensor drops out again. Also, take a look at your wiring in general, looking for cracked and broken insulation. Replace using soldered joints and heat shrink conections as needed.

Having said all that, I haven't a clue what is causing your headlight gremlins. I would look carefully at the harness in the area of the front core support, battery box and latch, searching for frayed insulation and bare spots. Pay special attention to the battery box area. This is where the two systems (hood cable and headlight wires) come close together. There is a lot of stuff squeezed into that small space in front of the driver's side shock tower. Alternatively, maybe the cable underneath the dash has worn through one or more of the headlight switch wires where the two cross each other.

[SVOeric]

I would think checking the wiring around the switch woiuld be a good idea. -- that is the area of where "things" are moving when the problem happens.

[dougk]

Thanks for all the informative recommendations so far: I've already discovered a suspect battery terminal cover that might have contributed to my flashing lights gremlin...so far so good on driving the car since clearing off several grounding points: I think the tps will be my next research point should problems resurface. Thanks again, you guys on this site are a gold mine!!!