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Good Evening,
I have a low mileage and very clean 1985 4 door turbo that has rediculous tail light problems. Thanks in advance for help from any of you that have been through this.
This car has 2 brake light bulbs on each side, 4 total. They drop out individually and regularly. There is no pattern to their doing so. The back up and tail (or marker) lights do the same thing although much less often. The only thing required to get them working again is to touch or wiggle the non-working bulb.
I have added a separate ground to each side. I have also removed and disassembled the connectors and cleaned the contacts. I did purchase some new ones from a Saabnet vendor and replace one that was cracked and one that was pretty badly bent up. I have also jumped from the left side wiring harness direct to the right side for the brake lights only to eliminate problems with power having to go through that left circuit board.
I have cleaned the blade contacts on the circuit boards with a jeweler's file and emery cloth and lightly coated them with dielectric grease. I have also cleaned the lamp holders in a similar manner. I used a dremel tool with wire brushes to clean the engagement points for the pins on the sides of the bulb bases, the ground points for the bulbs. I used emery cloth and shined up the positive contacts and all of this stuff has a small amount of dielectric grease on it also.
I have replaced all the bulbs so the positive contacts are not flattened. I am using GE standard bulbs (1057 & 1056) that have an oval positive contact which I find less troublesome in the Italian cars I also service.
I experimented with the pressure of the positive contacts and settled on having it moderate, about where the factory seems to have had it. The contacts make about 3/16" before the bulb can be locked into the socket. I have also tried bending the holder in so it almost grips the base. At one point I had it so tight it was difficult to install the bulbs. I have since returned it to what I feel is the factory setting. The bulbs install easly and the positive contacts hold the side pins against the bulb holder just like a set of un-altered boards I have.
I have also swapped in a set of boards from a 1993 900S with the same results.
When a brake light bulb stops working, I find very low (almost no) resistance from the ground plane on the board to the ground point under the trunk floor. I get voltage when I probe the connector from the back. I get voltage when I touch the + trace on the board all the way to where the bottom contact comes off the board. All I have to do is touch the bulb and it comes on. EVERY TIME.
Same holds true with back up lights and tail lights although they go out with less frequency.
I never have dim lights or signs of ground hunting. I have never been able to detect any voltage drop from positive at the back of the connectors to the end of the board trace where the + connector attaches. Nor any drop from the bulb holder to the ground point in the trunk.
I have completely removed the lenses and resealed them to the body. The trunk is pretty but probably not completely water tight. There is no correlation between rain and lights dropping out. Additionally, the car is garaged most of the time. It is however driven at least 4 days a week.
I would try to wire directly to the blade connectors if I could ever detect a issue there. I can't. I really would like to redesign and rebuild the boards with newer lamp holders that use pinned bulbs but see no way to do so.
Any help much appreciated.
Scott Shure
posted by 71.245.16...
, Mon, 25 Nov 2013 12:46:08, Mon, 25 Nov 2013 12:52:13
, Mon, 25 Nov 2013 21:02:53, Wed, 27 Nov 2013 15:57:55
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