Hey - New to the board...hoping someone can help. I have a 92' 940 FWD. I have been chasing and electrical problem for months. Alt. is good/tested O.K., but service light is on and eventually the headlights get dim and the gauges go SOUTH and when I shut it off it won't start. Also, when I hit high beams the gauges all peg (to the left). The shop has removed the inst. panel several times and say a "tab" is grounding out. They have sanded and tightened them but it still keeps happening. Help is needed - don't want to sell this great wagon...212,000 miles. Bruce'ster

Good morning!

I hope you follow the previous posters' advice and check to see if the system charging voltages are correct. If not, and the wiring to the alternator checks out ok, the problem could be the printed circuit in the dash cluster.

While I didn't have your charging problem in my '93 940, I did have a faulty gas guage and a non-working ABS warning light. Both problems were caused by tiny breaks in the printed circuit. This printed circuit is on flexible plastic and a bit too delicate for my tastes. I was able to find the tiny breaks using a digital ohmmeter ($5.00 at Harbor Freight) and a wiring diagram.

The wiring diagram is needed to find out, on the connector to the cluster, where the alternator circuit enters the printed circuit. The procedure is to connect one lead of the meter to the entry point and then visually follow the circuit trace making meter connections to points along the way. When the meter indicates a sudden high or infinite resistance, you know you have just passed the break.

In my case, there was a cracked solder joint along the path for the fuel guage and a hidden break in the circuit trace to the ABS light. Neither break was visible to the eye. The crack in the solder joint was visible with a 10X magnifier and the 'hidden break' was under a plastic tab where it was totally out of sight. I resoldered the first and soldered a bypass wire around the hidden break. Both problems have not reoccured in over a year now. Hooray!!!

Getting the dash cluster out was a bit hard since it had never been out before. The second time I pulled it, it was easier. I found how to do this using a search on this great forum. If you haven't done any circuit tracing, now would be a good time to learn. It isn't all that hard. Good luck!

Hi Bruce and welcome!

It does sound like bad connections in the instrument panel.

It would be very helpful to verify voltage with a voltmeter, both with the engine runnign and then not running. Should be 12.2 to 12.6 with key off, a bit less with key on (but not running) and 14-ish when the engine is running. This can be measured right across the battery terminals with any voltmeter- Sears sells a nice little red digital one for $20 (less when on sale), and it's fairly good quality- I like it for home use.

Voltage less than 13 would indicate the battery is in fact discharging as you are driving. Be sure the belt is not slipping, i.e. has no excessive flex in it, and then I would say that you've got to address whatever's wrong in the cluster. The mechanic seems to be on the right track- removing the cluster and tightening all screws is a very good first step.

Good luck with it! Hope this helps.
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::: Rob Bareiss, New London CT ::: 92 244 M47 211K ::: 90 745GL M47 273K ::: 88 245DL AW70 190K ::: 84 242DL Project ::: 70 VW Bus ::: 70 VW Pickup Project ::: 71 VW Notchback :::

A few things...
the 940 is not FWD, it is RWD
the service light is a mileage reminder. It can be reset by removing the small black rubber plug near the speedo, and firmly depressing the button (the ignition key fits the hole perfectly).

You need to determine whether your no-start is because of low battery voltage (poor charging or tired battery), or an electrical problem in the solenoid powering circuit. I am >assuming< that you are saying that the starter does not engage when you turn the key.

Do the gauge complaint and the dimming lights happen together? or are they not related? I ask because the signal to keep the alternator in 'charge' mode goes through the BAT light on the dash.

Dear Bruce'ster,

Good p.m. and may this find you well. So far as I know, all 940s are RWD (rear-wheel drive).

I think the problem has to do with the circuit, that runs from the alternator, to the alternator charging light, in the instrument cluster. The "draw" from that lightbulb "stimulates" the alternator to charge. A thin red wire runs from the back of the alternator to the instrument cluster. I do not have a wiring diagram for 1992 model year cars, as I do not own one.

If that circuit is interrupted - broken wire, corroded contact, burned-out bulb, etc. - the alternator will not charge.

The gauges' malfunction suggests that the instrument cluster has wider problems. the easiest solution might be to go to a salvage yard, get an entire cluster, and get the speedometer re-set, so it shows the miles on your car.

You can contact APT Instruments (Bloomington, MN). They charge $50-60 to re-set a speedometer. If you want to do this, I can provide detailed guidance as to how to remove the speedometer from the donor car's cluster. When you get it back from APT, you can put it into the donor car's cluster, and install that cluster, in place of what is likely a failed factory-original cluster.

Sometimes, the flexible circuit card develops micro-cracks. These are far too small to be seen with the unaided eye. Sometimes, corrosion can disrupt a circuit, but the corrosion is so small, that it is hard to find.

Hope this helps.

Yours faithfully,

spook