CraigL

1993 GTS (early)

Thanks to a leaky dash evaporator, I'm in the middle of a "20 year dashout R&R project". There is a lot going on with the pod and I could use suggestions. Obviously the dash, central console and pod have been removed. I've reinstalled the dash and the pod. The car starts without hesitation. But all of the dashboard warning lights are ON. The gauges seem to function well. I haven't tested the speedometer but that seems irrelevant.

Given the number of warnings, it is obviously a problem with electronics. There is no way that the oil pressure, water temp, brake lights, abs system, charging system have all suddenly failed.

Here's what has been done:

Evaporator replacement
Blower motor replacement
HVAC reseal and reinstallation
New vacuum actuator diaphragms
Carpet out
Roof panels loosened on rear and passenger side (sat antenna install)
Ground cleaning behind pod and above CE panel
Instrument panel LED upgrade

A lot of cables and connectors have been disconnected and reinstalled. In fact, I'm pretty sure that all have them have inspected.

The interior lights work in passenger footwell, and near windshield mirror.
The rest of the interior / courtesy lights are disconnected.

From my reading, there seems to be a module that controls the warning lights. Where is that located? To be frank, there are modules in every nook, cranny and cavity. Until you pull one of these things completely apart, you won't have an appreciation for just how hand built they really are!

Thanks in advance. Oh yeah, the AC is cold!

CraigL

A few more pieces of info:

I also replaced the ignition switch with a genuine Porsche part
I have verified that the 4 card edge connectors are properly installed on the instrument panel

Bill Ball

All the warning lights are suppposed to come on initially and stay on until about 2 seconds after you start the car, except for the brake warning which stays on until you press the brake pedal.

So, I gather all the warning lights are staying on after the car starts.

Here's a relevant thread....

https://rennlist.com/forums/928-foru...s-stay-on.html

What does the voltage gauge show? Normally with alternator failure I expect the central message screen to show "power save", although the above thread does not mention that.

Check the voltage at the engine jump post with the car running - it should be 13.5+V

Let's say that's not it.....

There was a bad batch of ignition switches a while back. Where did you get the switch?

pcar928fan

Disconnect the battery for 5+ min and then reconnect... Good and easy first thing to do!

CraigL

The battery was disconnected overnight. No change in behavior.

At the jump post, the battery reads 13.1 volts. With the engine running, it reads between 13.8 and 13.9 volts.

There is a very slight flicker in the LED lights when the engine is running. It is most noticable when viewing the instruments at an angle. That might be a natural feature of the LEDs as opposed to original incandescent bulbs.

Right now I cannot find the old ignition switch. I will have a different one to try in a few days and will report back.

Thanks. Keep the good suggestions coming!

CraigL

I reinstalled the old ignition switch. No change in behavior. Almost all of the warning lights are ON with the engine running.

The reason I had a new ignition switch was that several months ago the old one had a hiccup twice in a day - with the X bus not being energized. I ordered a new switch back then but that problem has not recurred. I suppose that I now have two bad switches. But that would be a stretch!

Suggestions are welcome. Thanks.

SQLGuy

From the wiring diagram, it looks like most of the warning indication logic is in the instrument cluster itself.

Is there any change in the warning lights between when they should be on (key just turned on) and when the car is running? I would be looking for whatever signal it is that tells the cluster that the car is now running. I would think this would be RPM > 300 or so. Does the tach work correctly?

I'll take a look at the behavior of my car later today and let you know what I see there.

BTW, did the cluster ever work after installing the LEDs? Are you sure the boards were reassembled correctly and seated completely after installing them?

CraigL

All of these mods occurred in the few weeks. I did not test them one by one.
After the engine starts, all of the warning lights go out for a few seconds and then they go back on.

The tach is working properly. I do like the idea about a tach signal triggering the lights off.

I have looked at the edge connectors and the internal pin connectors very carefully. Everything seems to be lined up. I do not have to force any of the instrument panel layers back together.

As part of the LED upgrade, Ed Scherer advises to solder a 390 ohm resistor into the board to keep the air bag light from being dimly light when off. To be frank, the soldering takes place in tight quarters. I did it with a magnifying lamp and tested adjacent pins for lack of continuity. It is possible that this created a problem. I can't verify that I did it correctly (not working), but I thought about it and was careful. Regardless, I removed the resistor. No joy.

CraigL

Found it.

Soldering issue. There was a small bridge to an adjacent pin when adding the 390 ohm resistor in Ed Scherer's guide. Now all the warning lights cycle on then off shortly after the engine starts.

With the exception of an airbag malfunction light that I suppose is semi-permanent. Well, now I can continue with my reassembly of the interior. I will be on the lookout for someone with a Hammer or other airbag code resetting device. Thanks to everyone who thought about this.

Ed Scherer

Good deal! Sorry I didn't offer any help sooner; I just saw your PM and this thread a few minutes ago.

What's the story on your air bag light? Do you know what triggered the fault in the first place? Need to make sure you address the problem before resetting the fault, or it will just re-trigger. Most common cause is resistance at the front crash sensor connectors (I can direct you to threads on that if you need it).

SQLGuy

The airbag will come on and stay on if the ignition was turned on while one or both airbags were disconnected. A hammer or a Durametric can clear it.

I bought a Durametric enthusiast kit to clear mine, and to have around to reset the oil change warning on my wife's Cayenne.

Ed Scherer

BTW, in a PM, you mentioned that you might make it to the Wichita OCIC, but not with your 928. If by chance you do wind up being able to take your 928, I could take along my 928-ecu-repair DT999 and/or JDS Porsche Spanner; one of these should be able to reset that air bag fault.

Bill Ball

Craig:

Glad you found the problem. The air bag warning can be diagnosed and reset with Theo's 928 diagnostic tool as well.