abs problems

Please bear with me as I am new to volvo ownership and on my first post. Already my relationship with my 1994 850 est is a little strained. Having already sorted out little niggly issues like lights and windows I came to the abs problem. After looking thru the forum I found the fault codes for the abs unit which was giving 4-4-4 no supply to hydraulic valve unit. Asking at a local volvo breakers I was recommended to replace the whole abs unit which that breaker didn't have but another local guy did. After fitting the replacement unit and bleeding the brakes last weekend I was sure everything was going to be OK. How wrong. Same light on, same fault code, so I still can't take it for an MOT. Can anyone suggest what else I could do to solve this problem on a car that is untaxed and unMOT'd, but in every other respect first class. Could the problem be the abs relay? Or is it likely to be the wiring and if it is how do I check the continuity? thanks in anticipation Stoddy

Common problem use the search facility and search for dry joints there is a thread regarding abs repair it explains how to remove the unit and resolder the power connections

welcome to the forum.............kev

The dry joints issue applies to the later ABS unit not your unit. Supplies to the hydraulic unit are derived from the combination relay shown mounted near the ECU. Fuses 11/9, 11/12, & 11/14 supply the ABS system, I would consider checking these fuses and the connections to the combination relay.

thanks for that, the fuses are Ok so I think I will look for a new relay, but perhaps clean the connections as a first try thanks for the welcome Stoddy

Did you delete the fault code in the OBD after installing the new unit?

Yes before disconnecting the old unit I cleared the fault code and then on refitting and powering up the abs dash light stayed on and I checked the fault code again which was still the same 4-4-4. Have sourced a relay to pick up tomorrow so with luck that might solve the problem and I might be able to get the car MOT'd, because I am sure evrything else is fine. Stoddy

take the bulb out for mot.