'81 help questions on instrumentation

[David D.]

Friend of mine has an '81 with 6700 original miles. After sitting for a year he finally took it out for a ride. Prior to this recent ride, everything worked correctly. Now the problem(s) are that the choke light stay on all the time, Tach gauge sits bottomed (approx) 1.5" below 0 rpm, the temp gauge sits/stays approx 125-130, fuel gauge sits pegged beyond full, he occasionally has an intermittent 'check engine light', and run has 'run on' after turning off. I know that a car sitting for long periods is not good, but all this stuff going bad, all of a sudden, just doesn't make much sense.

Before we pull gauges / panels, I remembered that the last time he had car out was for a show, where we were messing with the wire shielding in engine bay. I am wondering IF we might have hit/loosened some sort of bulk head connector, or some module, or?

My question(s):

1. Is there, possibly, something in common with all of this?
2. If YES, where would we find this connector? Location?
3. If NO, I know center gauge console is susceptible to breaking 'ears' off panel. What do we need to know on removal/installation?
4. Is there any documentation for removal, etc...?

Many Thanks in Advance,
David

[Edward J.]

Re: '81 help questions on instrumentation

David, I dont have a wiring dia. in front of me but it sure sounds like its all related maybe theres a fuse blown, its been awhile since ive been under the hood of a 81 , but I do beleive theres a fuse for the choke or maybe the gages.

[Tom B.]

Re: '81 help questions on instrumentation

I don't see a common connection to all of your problems unless it could be the instrument panel ground. Black wires are ground wherever you find them. Usually when a multitude of problems show up at the same time it is a ground. It might also be the gauge cluster connector located behind the instrument panel, but it is really difficult to accidentally pull one of these apart. With a car that sits a lot there could be dampness that is causing corrosion in the connectors. Unplugging and replugging the connectors for the circuits in question might fix everything. Other than that here's what I do know.

An illuminated Choke Warning indicator means a loss of voltage to the choke heater. Check the 20 amp choke heater fuse at the top of the fuse panel marked C/H. If ok check for voltage at the choke heater connector, brown wire. If the fuse is ok but there is no voltage to the choke heater there may be a bad choke heater relay mounted in the lower console by the shifter.

The tach is on the gauges and Brake Warning light circuit, 20 amp fuse located on the left side of the fuse panel marked gages. The brake warning light will come on for bulb check when the ignition is first turned to on or start. The circuit can also be checked by applying the parking brake with the engine running. The tach should set about 400rpm with the key off and drop to 0 when the ignition is turned to on.

The temperature gauge is powered by the same gauges fuse and grounds through the temp sender in the cylinder head. The needle sets where your is when off or on, not running and cold. I'm not sure if it drops down when it's started and not warm or not. I didn't start mine to check. I would think that it does though.

The fuel gauge is powered off the same gauges fuse as well as the Low Fuel warning lamp. The circuit goes through the tank sender and grounds to the rear lights ground. The gauge circuit has to be grounded to bring the guage down to zero and then the sender varies the resistance allowing the needle to rise when the tank is full.

The check engine light may be warning of the choke problem and this could be related to the engine run on too. I'm seeing 2 seperate problems here. The choke circuit and the gauges circuit. I'd start with checking the fuses mentioned.

Tom