My new to me 1982 has an intermittent problem with the warning lights on the cluster. Everything works perfectly except the bulb test function. It worked for the past months then they suddenly stopped coming on the other day when the ignition is turned on. The individual lights themselves still trigger properly, they just all don't come on as they should at the first ignition position.

I confirmed the CWU is getting power at the black plug but have not went any further. Any ideas where to look?

 

While I hate part swapping, it does become convenient when you have access to parts cars.

I swapped out an unknown CWU from one of the parts cars and all is back to normal.

 

When you say CWU, do you mean the unit beneath the dead pedal in drivers footwell?

Best functional description of that unit seems to be in electrical files within Morehouse CD. Also have seen snippets within the annual tech releases for each model year.

I guess I'm jealous. Am more worried keeping lights burning on the tailcone. You've advanced to troubleshooting the status light for the bulb monitoring system. Congrats, but lol at my folly.

 

Yes, CWU. The central warning unit under the dead pedal.

So this is funny to me......my 79 had a persistent problem with the stop light warning. I replaced all the bulbs with no result. So I decided to take the time with this car to test all the CWU units I have and all the bulb warning modules that I have as well.

Out of 7 bulb warning units, only 2 were good. Two had a stop light warning all the time. Two had a stop light warning that only came on when the pedal was applied and one had a tailight warning.

I also played with bulbs to purposely trigger a failure warning. The good units set off the warning light with a missing or burned out bulb but installing two different brands made no difference. This is totally not scientific. Just curious

Out of the 7 Central Warning Units. Two lacked the bulb test feature, one had no light at all and 4 were good.

So if you are pulling your hair cleaning grounds and changing bulbs, these units are certainly capable of failure and seem to exhibit that failure in different ways. I know this has been well covered before but I wanted to put a period at the end of sentence.

 

I had a similar problem with my '83. In 1984 Porsche introduced a new bulb tester that was all solid-state instead electro-mechanical. See excerpt below.

I changed mine out with a used new-style unit that I obtained from 928 International. Somewhat smaller, but works perfectly.

 

So has anyone taken apart a CWU to see what is wrong, maybe a bad trace on a board that can be resoldered etc.