ABS system work fixed my odometer but not my speedo

[RedBrickCollector]

1998 850 T-5, A/T with no TRACS. I followed the midwest troubleshooting guide today and currently my odometer works, speedometer does not. No ABS light, functions on the trip computer don't seem to work still.

I resoldered the small pins on the ABS module, all of them to play it safe. My module had been opened by one of the previous owners apparently.

Next was finding that the harnesses on both front speed sensors were bad. RHF was missing the contact on one female end, LHF only had the pins, no more plastic socket. Pins were shoved in there and covered in white RTV, which had gotten in between the pins. I did a couple "temporary" type fixes to get contact. 1100-1300 ohm readings at the harness for all four speed sensors after. I'm not sure if my sensors are out of spec or my multimeter is.

Last was replacing the insulation of the ABS pump motor with some heat shrink. Reading 25-26 ohms. For both the motor and LHF sensor I cannot be certain the polarity is correct.

I'm going to call it a win for now and tackle this again soon. My best guesses would be one of the following:

• Odometer takes RHF speed signal and speedometer takes LHF, which is why only one works. Bad connection or reversed polarity on the LHF speed sensor maybe?
• My solder wasn't thorough
• Instrument cluster problems
• Missing tone ring. I did not think to check for this.

[xanthefin]

Your Trip computer handles speed signal on Speedo in certain way actually so focus at it.

If you think info button switch is faulty you can take it off and replace with jumpers to "wake up" COMBI there is reference how the switch works in wiring diagrams for 850.

I assume you have VDO and not Yazaki dashboard ( this matters on 850 models, not V70 ).

[RedBrickCollector]

Seems to have been fixed by using better quality contact cleaner for the instrument cluster harness connector, one that removes oxidation and not just contaminants. Hopefully this helps someone.

[Clemens]

Out of curiosity: which cleaner did you use?

[RedBrickCollector]

I used Deoxit D5