Hi! I am eagerly going to write on my speedometer board repair later. Its a long whole story and experience. It was so funny that the instrument cluster in this 940 (same goes to certain 240s and 740s I beleive) does significant job to your vehicle runnings. Let me share some of my experiments & PLEASE DO NOT REPEAT THE MISTAKES.
As I would like to have a look at my speedometer circuit board, I detached the instrument cluster altogether. They are just meters! My car still could be started without it, with no air-conditioning. I well understood that the climate control box may be powered from the instrument cluster wires as well, so no big deal. I found my speedometer board having some burnt components, the popular leaky capacitors and a burnt resistor as well. So I left the instrument cluster inside the house, start the car, drive around the town searching for the components. Suddenly after a park, it cranked slower. Oooppss the battery is dying perhaps, dropped by a battery shop while leaving my car engine running in front of the shop. While negotiating the battery price, it dies automatically. So the car told me "DO NOT BUY THE BATTERY!".
Thanks to En Roslan, borrowed me a battery adequately for me to drive home and recharge my weak battery. Know what, it is just because of no instrument cluster, your alternator will not work. The moral of the story is "DON'T DRIVE WITHOUT INSTRUMENT CLUSTER"
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| No instrument cluster means NO A/C and NO ALTERNATOR |
Keep on thinking why on earth the VOLVO engineers designed the system as such. The meters are so important, as without it you cannot drive. Perhaps another safety features for you must be all aware of your car (speed, rpm, temperature, any warning lights) if you want it to get running. If not let the car die by itself and you are denied from continuing your journey, great!