Volvo Forums - Volvo Enthusiasts Forum - Erratic 850 Speedometer Troubles

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- - Erratic 850 Speedometer Troubles (https://volvoforums.com/forum/volvo-850-16/erratic-850-speedometer-troubles-14222/)

Quote:

Originally Posted by 850man (Post 95051)

I just wanted to let everyone know that I finally figured out what was wrong with my 850’s speedometer (working sometimes and not working other times). A very smart Volvo mechanic finally told me it was the ABS unit. I thought he was pulling my leg, but I contacted WWW.AUTOECU.COM, and they verified that the ABS unit would definitely cause the speedometer to work erratically (speedometer sensor wiring runs through the ABS module). I removed the electronics portion of the ABS (also found out you can take this part off and drive fine – no brake fluid loss or anything – brakes still work, just no ABS – until it’s reinstalled) and sent it to WWW.AUTOECU.COM. They rebuilt the module, updated it, and fixed any potential problems. They were great. I had it back in a few days, and it fixed the problem just like they said it would. BTW – the electronics part of the ABS isn’t so bad to take off, but you do need a small reverse Torx socket to take out the 4 screw/bolts. The wiring just unplugs. If the screws were easier to get to it would be super easy. I did have to remove the air filter to get to these 4 module mounting screws. Anyway, just wanted to let anyone know that’s having erratic speedometer problems, it could be your ABS – especially on a 1997 Volvo 850. I searched for months, replaced parts, and couldn’t find any info on it anywhere on-line – certainly not this solution. Just thought someone should share the info!

How did you like their service. They are only about 2 hours from me.

Erratic speedomter on 1997 Volvo 850

I have a 1997 Volvo 850..the spring on the key ignition does not spring back and has caused the speedometer to intermittantley quit the other day. I can juggle the key back and forth somewhat and the speedometer will jump back up. Is this a problem on the key lock cylnder due to the key not springing back or is the ignition switch going bad. I have read that the switch is where the spring back is located...any advice?

It wouldn't hurt to spray some graphite lube into the key slot just it might be binding but I'm pretty sure the spring unit is located in the electrical part of the ignition.

+1 With Kiss, going bad? Gone bad. Get the switch and replace it. Just a simple 10 minute job.

Quote:

Originally Posted by 850man (Post 72069)

I have a 1997 850 GLT. The speedometer works erratically. Occasionally it works just fine, but most of the time – nothing. The odometer stops when the speedometer stops. I tried replacing the speedometer, and the sensor on the transmission. Neither changed its erratic ways. I also tried unplugging and plugging the connectors under the dash, below the fuse block. I even tried jacking it up, putting in gear and watching the speedometer while I moved and shook wires. Nothing made a difference. Any ideas? Where could I get a schematic or drawing to show me exactly how the wiring runs from the sensor to the speedometer? I may need to trace out every inch of wiring. Any help would be appreciated.

My 97 v90 is having similar problems however, I am able to press on the plastic dash gauge cover which seems to awaken the speedo. Sometimes it sticks and other times it will drop right back down to zero, which makes me question my hyp. That if it is a threaded interface, dismantling the dash could gain me access to a quick solve. When the speedo doesn't work from a fresh start the car will will not shift from 1st and cause the transmission failure lights to go off. I also have buttons on the dash that are tempermental and take a bit of pressure to activate so maybe that whole region is going. So, loose spedo cable? Bad Abs module? Any help much appreciated!