courtesy lamp delay timer

[alwoody]

1982 coupe:
Problem - Courtesy lamps stay on after ignition switch turned off. Lamps operate corectly with ign switch in RUN position (e.g., lamps off with doors closed), but with ign sw off, key removed, doors closed, lamps do not go out. I pulled the delay timer (orange box to right of glove box), inspected for burns, loose connections,etc, all appears sound. 5 pin connector looks good. Suspect bad timer IC.
Does anyone know of a diagnostics procedure or ohms check to try before I replace the delay timer? GM stopped production in 2007, so I would have to go with an aftermarket module, about $100.00. I can try the wrecking yards, but I'll end up with another 25 year old module.

Thanks

 

[wishuwerehere82]

The timer module has a simple R-C timeout circuit that discharges a capacitor on the board through a resistor.
Once the minimum voltage threshold has been reached at the transistor base, a transistor shuts off the current running between the emitter and the collector.
So either the resistor or capacitor is open and never discharges to timeout, or the signal that the doors are closed isn't getting to the board. If the transistor was blown, the lights would never come on.
I would try putting a little extra solder on the board edge contacts to get a good connector contact before trying to bebug the module internally.
But if you do, you will need an analog voltmeter or a scope to read the input signals to the capacitor and monitor the voltage decay rate.

 

[wishuwerehere82]

The timer module has a simple R-C timeout circuit that discharges a capacitor on the board through a resistor.
Once the minimum voltage threshold has been reached at the transistor base, a transistor shuts off the current running between the emitter and the collector.
So either the resistor or capacitor is open and never discharges to timeout, or the signal that the doors are closed isn't getting to the board. If the transistor was blown, the lights would never come on.
I would try putting a little extra solder on the board edge contacts to get a good connector contact before trying to bebug the module internally.
But if you do, you will need an analog voltmeter or a scope to read the input signals to the capacitor and monitor the voltage decay rate.

Or get one on Ebay.
http://cgi.ebay.com/ebaymotors/78-8...hash=item350072516717&_trksid=p3286.m14.l1318

 

[George81]

When you find the timer behind the glove box right side, splice the two white wires together eliminating the timer function follow the link sorry the pictures no longer populate? Ask mkapp7879 to send to you again! This works great, been through 3 and every year when I bring the car out of moth balls and charge the battery it seems to blow the timer! Also same link there's an address to send for repairs too!

http://www.corvetteactioncenter.com/forums/showthread.php?t=94752&highlight=courtesy+light&page=2