Hi. My abs light is very intermittent some times it's on other times it's of but when it's on the Speedo doesn't work. If you turn ignition off restart engine sometimes it goes off other night take a couple of attempts before it goes off abs unit rebuilt last year. Is it possibly the ignition switch that's at fault of something else. Also no codes stored. Thanks MICHAEL

 

what year is your 850? ABS codes are a separate code set from emissions codes so there's a different jumper port to use for the 94/95s and for the 96+ models you need to use a fully featured code reader than can scan for ABS and possibly chassis fault codes. The fact that the speedo stops when the light is on strongly suggests an ABS controller issue, a wonky speed sensor or a wiring/ground issue. To note the speed sensor goes to the ABS controller than to the speedo so this could be a bad sensor, a bad ground (say to the transmission?) or solder cracks in the ABS controller. Check out Midwest ABS or XeMODEX for some content on ABS controller faults/symptoms.

 

Hi. I have had the electronic box for the a b s rebuilt the car is a 1996 850 but I've just come home and turned the ignition off and the radio and all accessories are still on so I've had to disconnect the battery. I think it might have just answered my question for me New ignition switch

 

I had this same issue. The ABS module needed the capacitors changed out to correct the issue. It is not too bad to do yourself if you are handy with soldering. Here is the guide I used:

"Do it yourself ABS module repair."
https://www.matthewsvolvosite.com/fo...ic.php?t=12651

Good luck! Let us know!

 

Jollygoldgood. It turned out to be the ignition key switch I'd already had the A B S unit rebuilt earlier for MOT latter part last year. Michael