timabe

This morning I cranked up my baby for a little Saturday morning fun and discovered the following four items have stopped working:

1. The radio
2. The computer display under the tach no longer lights up (it works, just dim)
3. The little red lights in the door panel that should blink when I press the immobilizer button on the key fob
4. The clock.

Everything else works fine. I checked the corresponding fuses for these items and they all seem to be good. Anyone have any ideas?

NC TRACKRAT

I'm betting that you've lost a common ground for these items. See if you can trace back the ground wire (usually brown) on one or more 'til you can find where the point is that they anchor to the body. Even if it looks o.k., there may be corrosion preventing a good ground.

matt777

I would check the battery voltage with a multimeter. It could be low for various reasons.

timabe

Battery and charging system check out fine. It looks like it's a ground issue.

Anyone know if there are any common ground connections near the front bumper? I had the bumper removed and resprayed last week. I wonder if there was a ground wire that was left loose?

This is going to be fun.....

NC TRACKRAT

Considering the various items that are giving you a problem, I would bet that the ground affected will be in the under-dash area, perhaps near the kickpanels or underdash metal structure.

timabe

Well, thanks for the suggestions, but I spent all day trying to figure this one out and had no luck. I guess I'm going to have to take her to the dealer. Ugh! I'll update the thread once I have a solution.

timabe

I finally had time to take another look at this today (I really HATE going to the dealer and have been putting it off). I found that the aftermarket radio had an inline fuse hidden behind the glove box and the 10A fuse was blown. I replaced the fuse and the radio started working fine.

Now, I'm left with the following still not working:

1. The computer display under the tach no longer lights up (it works, just dim)
2. The little red lights in the door panel that should blink when I press the immobilizer button on the key fob
3. The clock

Anyone have any other ideas? I've checked the fuses once but will check them all again tomorrow.

NC TRACKRAT

Aha! Aftermarket radio! There's a strong possibility that whatever caused your radio to blow a fuse has played havoc with those other functions. Also check to see that the green wire is still connected to the chassis frame that receives the radio. If it's not, your IMMOBILIZER thinks that your radio has been stolen. Incidentally, a 10A fuse is way too big. By the time a 10A fuse blows, too much could've fried. Look for any other wires that seem brittle or charred.

timabe

Come to think of it, I did see an orphan green wire hanging back there behind the mass of wires. It has a connection "socket" and I didn't see anything for it to connect to. I assumed it was for the original radio.

When you say "still connected to the chassis frame that receives the radio" what do you mean?

Thanks for your help!

NC TRACKRAT

Normally, the green wire's terminal is attached onto a special tab of the metal chassis that supports the radio (the thing that the radio slides into). To get to the tab on the frame, you'll probably need to extract the radio from the front with the proper tools to gain access. The easier solution is to wrap the terminal of the green wire with tape to isolate it. If it is grounded, it tells the IMMOBILIZER that your radio is missing/stolen.

Slow Guy

I thought it was the other way around, if the ground was missing the radio was stolen. The immobilizer wants to see that green ground. (I think, not 100% sure on this though).

NC TRACKRAT

As I said, it's a special terminal on the radio frame's chassis that keeps it isolated until it's removed/stolen. Once the radio is pulled out, it grounds, thereby signalling the IMMOBILAER that something bad has happened. That's why it's important, if the wire is loose, the end terminal of that wire should be insulated to avoid it grounding.

timabe

This morning I removed the aftermarket stereo and the cage it slides into. In looking at the jumbled mess of wires I found two connection harnesses that are not connected to anything on the stereo (circled in red). I assume these are for the original stereo.

In addition to the green wire, I found a white wire that was not connected to anything. Note that both of them are protected by a plastic cover (or, plug). Thus, I have both a green AND a white orphan. I looked everywhere I could and I could not find anything that these orphan wires should plug in to; especially on the cage.

This is making me NUTS! Mechanical problems I can deal with. Electrical……not so much.

Any ideas?

NC TRACKRAT

Nope! No ideas. As long as that green wire is insulated from ground, it won't affect the IMMOBLIZER. With the OEM radio, it would've attached to the rt. hand outboard side of the metal frame that receives the radio. You should see a metal tab where it plugged in....but don't!

geolab

this is correct. The green wire connects to the radio rear housing,
If alarm is armed, and radio pulled, the lack of ground on the green wire will trigger alarm.
This wire is short on purpose. so that it looses ground halfway pulling the radio out, and trigger alarm.
Porsche mechanics lay down heads up in the passenger footwell, to hook the green wire after an install.
If the green wire is not connected in the first place, the alarm neglects its role, and nothing happens. regards