My 87 has what appears to be a grounding problem for a year now. The car will idle perfectly with my auto x ray plugged into it. This is with the xray device turned off. When I unplug the xray, the car reverts to idling at 800 rpm.
I am also having the interior lights work intermittently when you open the doors.
Sometimes they turn on, sometimes they do not.
The rear hatch release button located on the driver's side door works intermittently also.
I can't help but think these are all related as they seem to have started around the same month.
The driver's side brake light works intermittently also. The rear light works when you turn on the lights and the turn signal, it just goes out when you step on the brakes.
The radio is not recieving any AM reception and little FM. I did have the dealership install a new antennae and coax last year. I had problems with the radio reception and they claimed they knew nothing about why it was not working. (guy said it was my car :rolleyes:
Any suggestions on where to start looking?
Thought about replacing the ECM in regards to the idle, replaced all of the sensors under the hood and tripled checked their readings. They are set correctly.
:confused:

 

The interior lights are turned on by a switch in the door frame. Check the switch with an ohmeter and look at the condition of the wire spade and the switch lug. Do the same with the hatch switch and check the condition of the wires that go through the door as they get flexed every time the door is opened and you can flex a wire only so many times. Brake light could be due to a corroded socket or its ground connection. The ground for all of the rear lights goes to a common point, S400 behind the RH side stop light sockets and from there they go to a 4 pin plug in socket RH side of the cargo compartment, rear of the wheel house....and finally to a frame ground, G401 (coupe) middle of the center lock pillar. Get the electrical diagnosis service manual supplement which has circuit diagrams, pictures of component and wiring locations and check procedures. Unplug the antenna wire from the radio and check with an ohmeter the continuity of the center pin to the antenna rod and from the shield to ground. Water in the coax can greatly reduce the received signals too. Plug a wire into the radio antenna jack and hold it outside the car and see if the radio receives better. If it does, its your antenna or coax, if it doesn't , your radio needs servicing. Idle is supposed to be around 800 rpm and I have no clue why plugging in a diagnostic tester would affect idle. Good luck, I have an 87 and I drive mine everyday.

 

Thank you, I just got a hold of the "electrical diagnosis service manual supplement" book.
Do you know if I should invest in the plate that mid america sells that is supposed to improve antenae grounds? They call it an upgrade that is standard in the 88s.
I have had my vette for almost 10 years now and this is the first time these symptoms have come up. I usually drive it every day, but it has been sitting idle for a cuple of months while I figure out what was wrong with the tail light... officers here have warned me already in regards to the intermittent stuff. No fix it tickets yet.

:auto:

 

There is no plate on my 87's antenna and my radio works fine. I am assuming that your radio worked ok at one time and it doesn't have a plate. The plate is merely a ground plane since our bodies are insulators. Vertical antennas work better with ground planes and the largest effect would be noticed on fm. When you connect a piece of wire to the center conductor on your radio's antenna connector, you will find out if your antenna is defective or the radio.