Tracking down grounding points

[Sam]

I took my new 89 spg to get inspected this weekend and the shop decided to replace my front pass side bulb as he said it was bad. The guy didn't get the turn signal in right and now there is about a half inch gap between the headlight and the turn signal which I have to now address.

Since he did this, my fuel and temp gauges move with the right turn signal, but only when the headlights are turned on. I assume this means there is a bad ground somewhere. I thought this would be a common issue but i haven't found much info. I'm assuming the bad ground is in the headlight area and not on the gauge cluster itself. Anyone else run into this problem?

[87 n/a]

There is 1 torx screw that ties the headlight and corner light together. Might not have even been reinstalled.
The nearest ground point to that lights is located next to the passenger side bottom corner of the radiator.

[Geoff]

Any time I've seen weird electrical problems like that on C900s it's been because someone put the wrong bulb in somewhere.
Example: My dad had a car that would only turn on the headlights when he stepped on the brakes. It turns out someone put the wrong tail light bulbs in.

I think bulb reference books tend to call for the wrong bulbs for these cars. Pull the light out and make sure it's the correct bulb.

[DrewP]

^^ Good tip.

I've also seen the cluster do weird stuff like then when the back of the cluster gets all corrodey or the ribbon comes apart, but seems odd it happened after other things got messed with and not the cluster.

[Sam]

So, I now think its the turn signal stalk thats causing the issue. I noticed that switching on the cruise control also causes the gauges to move. I'll have to hit my c900 parts bin for a replacement. These things have gotten pricy. I would have just bought a new one to save me the hassle but they apparently are no longer being produced for the pre 1990 cars.

[gmreider]

Sam , before you spend $$ for a T/S switch, I would look around the area where the garage guy was working ( or screwing up). It all sounds to me like a lack of good ground issue. Usually if everything was fine until someone worked on an area- look at the last work done.
If you know how to take the corner light assembly out , do so and look at all the wire connections. Look closely at the ground strap connection from the battery where it bolts to the chassis on the right side.
I've worked on a lot of SAAB 900's and I have replaced zero T/S switches for what you describe.
If need more help, I'll have to think of a test procedure for you to do.

[Sam]

Cool, I will check that again. I have a t/s stalk up in my parts pile which is about an hour from where I live so I was just going to use that one.

I took a look at the area and I did find that the replacement bulb was the single contact type, which I replaced with a 4 patch that I had sitting around. I hoped that would fix it but it did not.

I also checked the rear bulbs and everything seemed ok there.
I'm slightly afraid that I touched the instrument cluster while Installing replacement speakers in the front but I was pretty careful. The previous owner had monkeyed around with the stereo wiring so I had to patch it back together to get the stock stereo working again.

The strange thing is that everything worked for a few miles after both jobs had been completed, then after driving approx 5 miles the problem showed up. I know that the previous owner had already replaced the turn signal stalk but the replacement has a lot of visible wear on it. Since the cruise control modifies the behavior, I assumed that some wires were getting crossed in the signal switch. The cruise control can also cause the behavior to happen on its own. IE, the car is started and gauges show as normal up until the point where the right signal is turned on. If I turn on the cruise control instead of the turn signal I get the same odd behavior in the gauges.

The issue ceases to happen when the turn signal fuse is pulled, making me think that the cruise control switch is what is causing the problem.