Recently the ABS light on my 94 volvo 850 wagon (180K Mi)came on and has been lit ever since. Local mechanic is expecting min ~$150 to diagnose the problem. And pending what they find it could be an expensive problem to solve. Anyone have any thoughts on what to expect from a repair perspective? Or is it time to move on to a new (to me) vehicle?
How is the vehicle running? If it’s running good I would invest the money to see what the problem is. If it’s simple and not too expensive I would get it repaired. If it’s expensive I would sell it “as is” and invest in a new vehicle. A lot of people including myself can take or leave ABS. I find it to be a nuisance especially in older vehicles.
Does the ABS activate during normal braking in dry conditions (does the car make a noise and shudder during a normal, dry stop)? If not, did you test the system in wet weather by making a hard stop, and if so, did the car skid or did it shudder to a stop (which it should)? The most likely cause in either case is a build up of brake dust on your wheel sensors, or a failed sensor. Either is as likely as the other.
If the ABS is working as it should in wet or snowy/icy weather, and the brakes work normally in dry weather, you have no immediate problem but you might want to have a Volvo dealer clean up and test your sensors for you. The clean-up should cost about $100.
I’d stay away from the “$150 to diagnose the problem” guy.
First, check the sensors at all four wheels for debris or a sensor that has gotten damaged or pushed away from its reluctor wheel. Examine the sensor wires for damage or chafing.
If there is no evidence of physical damage at any sensor, then it is likely that the control module has been damaged. I understand that this is common on 850/S70s.
There our places that specialize in rebuilding the control module, and will provide you with instructions for removing it and sending it to them. I don’t recall the name of the outfit that did my in-law’s S70, but it was in southern California and the company name was a Hispanic name, that is all I recall. They had it back in a week and the price was reasonable. That was 4-5 years ago and it still works fine.
If it passes inspection leave it be. It is not a safety hazard to drive with ABS light on. It simply means the system has a fault is off.