1993 940 Yazaki speedometer not working

zimmerdale · Post by **zimmerdale** » 20 May 2016, 22:09

The instrument cluster on my '93 945 is giving me fits.

When I bought the car, the speedometer didn't work and the odometer ran 3-4 times too fast. Very weird. After going over Art Benstein's great write up on the '93 cluster (http://cleanflametrap.com/speedo7.html) several times, I realized I had the same corrosion issue on one corner of my speedo board. I cleaned off the corrosion and found one tiny copper trace with a small section missing. I borrowed a friend's soldering pen and got a thin wire soldered in to fix the break. I tested for continuity and put it back in for a test drive.

The odometer works perfectly! I assume my copper repair brought a necessary resistor back into the circuit, or did something important to slow down the odometer.

Unfortunately, the speedometer still doesn't budge, so I still need to figure out that issue. I checked all of the obvious possibilities, with no luck. I verified that I have the original axle and differential. I replaced the section of wiring harness for the speed sensor sending unit from the differential to the inside connector behind the driver rear wheel well. Now that I got the odometer to work correctly by making a repair on the circuit board, I assume the speedometer is also related to a board issue. But I can't see any other obvious problems.

Does anyone have experience with these clusters who could point me in the right direction? Any suggestions are greatly appreciated!

Thanks,
Jason

93Regina · Post by **93Regina** » 20 May 2016, 23:16

zimmerdale wrote:instrument cluster on my '93 945

Volvo 700/900 Speedometer Repair

zimmerdale · Post by **zimmerdale** » 21 May 2016, 10:57

I've gone over all the repair guides and threads many times. The Volvo Club guide is for the bad caps from the '91-'92 clusters. My '93 cluster doesn't have that issue.

If I was better at reading electrical diagrams, I think I could narrow down the places to look. I know the signal comes in fine and gets to the odometer fine now. But the speedometer either isn't getting the signal or is malfunctioning in some way.

Does anyone know how to bench test the speedo?

93Regina · Post by **93Regina** » 22 May 2016, 06:46

zimmerdale wrote:speedometer either isn't getting the signal or is malfunctioning in some way.

I'd have to look at 940 diagrams, but if your cruise and ABS are working, this suggests rear-end counter is working.

Cleanflametrap's URLs were not working right this AM, but see this URL for an idea.

ktuuri · Post by **ktuuri** » 23 May 2016, 04:02

The contacts on the Gas gauge it's self may need cleaning , take them off and give them a cleaning, even if they look clean. Dexoit works very well.
I did it for mine and it brought it back to life, But I also reflowed all the solder joints on the circuit broad at the same time.