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Have had an intermittently functional ABS light on this car since I bought it. ABS system has always been functional regardless of light status. Basically, the light only comes on at startup when it is really cold outside, and usually only on the first start of the day.
Unlike most of the other light which have one or more solder joints that could fail, the ABS light has nothing but copper trace from the plug to the light and from the plug to the ground. Took an ohm-meter to the light socket. The trace from the harness plug to the socket showed continuity. Because I couldn't find the ground point, I tested continuity between the ground side of socket 9 (ABS) and 8 (low coolant, which was not used on my 940, even though there's a real bulb there). Found continuity. Hmm. Should be okay but it obviously isn't.
Then I pulled the light for 10 (parking brake) and checked for continuity between that ground and 9. Open. turns out that there is a crease in the printed circuit ground trace that serves lights 8, 9, and 10, just beyond the point where 10 branches off. I snapped off one of the little plastic fingers that covers it so I could look more closely and get a picture.
So tomorrow, I guess I will be digging out some light-gauge wire and soldering in ground jumpers. Given the likelihood that there are other similar creases at various points on the cluster where the printed circuit wraps around the bottom of the plastic structure, other lights could fail at any time.
John
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