1980 Power Door Lock Issue

[Tony D.]

Just purchased a 1980 corvette that is all original. Having issues with the courtesy fuse that keeps blowing when I install the 20 amp fuse.
I think I narrowed it down to the power door locks. Door locks when powered automatically lock every couple of seconds all by itself?
With no power I can manually lock and unlock both doors from locking mechanism on arm rest as well as from the key. Athough the drivers side is hard to lock and unlock (which could be my issue with it drawing extra current when powered causing fuse to blow).


I'm stumped as to why the power locks are locking automatically all by itself? Any suggestions? Could I have an issue with the Alarm circuit?

[Arland D.]

Re: 1980 Power Door Lock Issue

Holding down the door lock switch does not result in repetitive locking attempts so a short in the switch or circuit doesn't seem likely. You may have found the issue in the difficulty in getting the mechanism to physically work. Might be time to remove the door panel and get to know the locking mechanism.

[Tony D.]

Re: 1980 Power Door Lock Issue

Good to know that Arland. Thank you! I have seen in some schematics that the door lock actuators go to the alarm circuit? Could the Alarm circuit cause the doors to lock?

[Arland D.]

Re: 1980 Power Door Lock Issue

The theft deterrent system is basically a circuit board that reacts to all the different inputs to activate the alarm and kill the ignition system so it wouldn't drive the locking mechanism. The mechanical bind you described sounds like a good place to look.

[Tony D.]

Re: 1980 Power Door Lock Issue

Just checked and my 1980 does not have the theft deterrent module. Has to be one of the switches? When I hold one of the switches to the unlock position the doors do not unlock but it does stop them from locking by themselves. When I release the doors both lock then a few seconds later they try locking again. It is like the actuators are getting power to lock at all times? Both act together.

[Tony D.]

Re: 1980 Power Door Lock Issue

Any good instructions or videos out there on taking off the door panel of a 1980?

[Tony D.]

Re: 1980 Power Door Lock Issue

So, what your saying is what I'm seeing. Motor stays powered then goes off because of circuit breaker, then once reset it tries to lock again?

[Mike E.]

Re: 1980 Power Door Lock Issue

I just helped with an 80 with an issue with the same fuse. If I recall, there were 5 different items powered by that same fuse. In the one that I helped with the theft alarm was the culprit. Unplugged power to that, and everything else was fine.

[Tony D.]

Re: 1980 Power Door Lock Issue

I'm confused because I don't think the 80 had the theft deterrent system (which locked the doors automatically). My Alarm system I think only causes horn and flashers to go on. I was told that the alarm system or electronic module was included starting in 81.

[Tom R.]

Re: 1980 Power Door Lock Issue

Any good instructions or videos out there on taking off the door panel of a 1980?

If its like a 78, look for a couple of screws, like one toward the door jamb, arm rest and door handle. I've scanned the page for the door panel from the 1980 AIM...an AIM (assembly instruction manual) is essential for accessing car guts when troubleshooting.

1980 door panel_AIM294.jpg

[David H.]

Re: 1980 Power Door Lock Issue

Tony

Pages 8A-75 & 76 of your 1980 Shop Manual have power door lock circuits with a detailed wiring diagram and a circuit operation narrative.

Dave

[Tony D.]

Re: 1980 Power Door Lock Issue

Found issue to be the wiring (connector) and power door lock switch on drivers side. Diagrams I have showed a way to isolate the issue from driver and passenger side so once I found that it was the driver side that had a short I was able to locate it easily. Replaced switch and wiring harness and all good now. Thank y'all for the feedback!!