I've just completed three electrical repairs to my '93 940 wagon. Matbe others will find this useful.

1. Inoperative AC. This has been discussed in the 700/900 FAQ. My AC compressor would not turn on except sometimes when I whacked the dash. This is a pretty sure sign that there is an electrical connection problem. Pull the AC controller out of the dash (see the 700/900FAQ for how to do this). Remove an aluminum shield by carefully twisting the mounting tabes. Now look at the solder connections where the pins for the small black relay come through the board. It was obvious that two of these had gone bad. I resoldered them and the connections on the heavy wires where power enters the board. Replaced the controller in the dash and now the AC freezes your ***!

2. The gas guage was very intermittant and sometimes would work with a whack on the dash (see above). I pulled the instrument cluster and carefully examined the flexible PC foil traces on the back of the cluster. If you follow the three traces for the gas guage, you will probably find a cracked solder joint. I needed a 10X magnifier to see the crack. I resoldered the cracked connection and all other connections for good measure. Now the guage works fine.

3. When I finished repair 2, I realized that the ABS warning light was not coming on. Again, I pulled the instrument cluster and examined the traces to the ABS light. All solder connections were good (see repair 2). Finally I found the problem. That flexible PC folds under the cluster on the bottom and is held down by plastic tabs, a really poor design. The bend evidently places the circuit foil under stress. In my case, the foil trace for the common side of the ABS light had cracked under one of the tabs. You could not see the crack but the ohmmeter showed continuity to one side of the tab but not to the other side. I scraped the plastic off of the foil on both sides of the tab and soldered a small wire between those scraped areas. Now the ABS light works as it should.

I should say that the instrument cluster on the 900 series is much easier to work on than on the 240 series. The bezel over the cluster is a bit tight but, once that is off, it is easy to pull the cluster out. There was enough slack in the wiring harness to pull the cluster out, turn it around, and then measure voltages on the cluster without having to disconnect any wires. The connectors are well made and cannot be put back into the wrong socket! That flexible PC is likely the source of many instrument problems.

These problems come up from time to time so maybe my experience will help. Keep on bricking!