abs problem - novel solution ?

glasgowjim · Post by **glasgowjim** » Fri Apr 03, 2009 8:49 pm

Right

ABS does no work

ABS warning light on constantly

the diagnostic box works for everything except the abs socket which is dead so if i is not he relay underneath then if I connect to a replacement pump which is just tied up to the side then if the controller is well stuffed the new one wont be so it will give an error message

do you think it will work ???

going to try i tomorrow.

funnily enough the car brakes beautifully as it is

esta · Post by **esta** » Sat Apr 04, 2009 8:07 am

My ABS light stayed on all the time-one of the reasons it failed the MOT

So to pass MOT I tried several things as I didnt want to have to resort to taking the dial pod apart to remove the bulb

I removed the relay and voila, the light did its trick-a couple of seconds on to say its there, and then it went out-just what the MOT man wanted

So, relay removed...means no ABS right?! Wrong-just for a laugh I slammed on the brakes-ABS kicked in no probs-with no relay!!!!!

Now, someone tell me the 480 isnt full or wierd and wonderful surprises!

Melvin480 · Post by **Melvin480** » Sat Apr 04, 2009 8:54 am

Don't know if this is the case for the newer type ABS, but I had this problem with the early type ( '89) with the computer in the boot.

First I cleaned all the sensors, after that I cleaned every connector to the sensors, ABS unit and computer and still had this problem. I gave up and went to Volvo. The mechanic told me that he could try to find the problem not by diagnostics, but by measuring every connection and component one by one. The idea of Volvo working a full day on this without being sure that the problem would be solved made me investigate further myself.

I thought I had cleaned all connections, but then I realised that there is an earth point below the left rear cluster. The same region as the abs computer. Cleaned the earth and problem solved. Seems that if the ABS computer has a bad earth (or power supply, would give the same effect I think) it can not work properly. Maybe something to check. If you have the newer type of ABS with the computer in engine bay you have to find its earth yourself.

Iroll480 · Post by **Iroll480** » Sat Apr 04, 2009 1:46 pm

The warning light also stays on if the sensor(s)tip is/are dirty and/or the teeth on the hub are dirty. Here I've got the mark II ABS manual. I've got the mark IV manual only in german.

480_rocket · Post by **480_rocket** » Mon Apr 06, 2009 5:19 pm

I check the fault codes by bridging the diagnostics connector in the cubby hole in the boot and the light on the dash flashes the codes. I'm sure a search on here will bring up the wires to bridge, I read it from Tardis.

glasgowjim · Post by **glasgowjim** » Tue Apr 07, 2009 10:26 pm

its he mark 4 model 1994 and the relay underneath the abs pump is a pure bitch to disconnect

glasgowjim · Post by **glasgowjim** » Wed Apr 15, 2009 6:23 pm

disconnected it by taking out airbox to get room. removed the 4 pin connector then removed the relay from holder then found the wire retaining clip removed that and off it came changed relay no bloody difference!

well teed off