Volvo S80 - Bad ABS Module

For many years, my 2000 Volvo S80 has had many lights illuminated - ABS Brake Service Required, STC Service, Brake Failure-Stop Safely ASAP, check engine, etc. No one has ever found any problem with the brakes or been able to turn off the warning lights. This year, I could not pass the emissions test because the check engine light was on. My mechanic thinks it is a bad ABS Module, but has not been able to find a used one. A new one will cost well over $1,000. I am contemplating sending the ABS module to a guy named Vic Rocha who advertizes online to repair the modules, or to another online place called Module Master. My mechanic is skeptical. Anyone have any experience with this problem?

Your ABS system has absolutely nothing to do with your emissions. But the history of brake warning lights suggests you probably do need work on teh ABS system.

That Check Engline Light is the one that’s telling you you have something that may effect emissions. Without having the fault codes it’s impossible to guess what it is from here. The possibilities are endless.

I’m not failiar with Vic Rocha or with Module Master, but it doesn’t surprize me that someone has set up a rebuild shop for these. If it looks legit, I’d try it. Your car will stop even of the ABS is malfunctioning, so the risk is limited.

Thanks for your response. The fault code was Manufacturer’s Code 1633.

I’m unable to find Volvo DTC codes interpretations.

Help, anyone?

Modulemaster has a web site that can help you decide if you need a rebuild . I’ve used their service with good results .

Do you know that for a fact on the particular car? On my cars (LS), the ABS controller provides the VSS signal, so an ABS controller problem can trigger the check engine light on my cars. Could this not be true for the Volvo as well?

Volvo DTC P1633=Vehicle Speed Sensor Signal.

This code will cause the the Check Engine, ABS, and the STC lights to come on. This is an input to all these systems, and if these systems don’t how fast the vehicle is moving, they won’t function and turn their warning lights on to let you know.


The ABS system needs the VSS signal in addition to the wheel speed sensors?

The Anti-lock Brake System/Stability Traction Control along with the Engine Management system all work together to keep the vehicle under control if the driver goes over the limits of control. And in order to do this, all these systems need to know how fast the vehicle is moving


Cool. I forgot that the STC system uses the ABS system and they’re thus intertwined. It makes sense that the Engine Management System would be intertwined also. It would be counterproductive to have the STC system working the ABS system to keep the car under control while also having the engine pushing against it for more speed.

Hey, if my post caused ultimately the solution to the problem I’ll sleep well, even if it was the correction to my post that was the solution to the problem.

Sounds like the OP may need a vehicle speed sensor. A fraction of the cost of an ABS modulator.

Yeah. It’s like the older ABS systems. If the primary brake warning comes on, the ABS light automatically comes on. That’s because the ABS won’t function if there’s a problem with the primary brake system. And until you find out what’s causing the primary brake warning light to come on, that ABS light will also remain on.


The ABS controller provides the VSS signal, not the other way around.

Update on the ABS module repair for my 2000 Volvo S80. I had my mechanic remove the ABS module and I mailed it to Victor Rocha in California who, for $144 (shipping incl) repaired some cracks in the circuit board. My mechanic installed the repaired ABS module, none of the lights are one, and I had the emissions testing done this afternoon and passed. I can’t say enough good things about Mr. Rocha. I highly recommend him.

Volvo Girl