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DJLind · 06-01-2016, 11:55 AM

I have a steady ABS light lit on my dash and it is now @ Cummins to be addressed. However, I'm not convinced that they are on the right track with their diagnosis. They claim the pressure modulator valve has failed. The diagnostic code from the Aladdin system is "SPN 798 FMI 5" which in the manual is described as: "DA right PMV CMN open circuit". That seems more like a wiring issue to me. The replacement part is very expensive, and my extended service provider is reluctant to approve the part.

The service manager wants me to intervene with the extended service people and apply some customer pressure, which I am willing to do, but before I do that I want to feel more comfortable with the diagnosis.

Am I on the right track with my concern?
Thanks,
Doug L.
09 Endeavor 41SKQ

jacwjames · 06-01-2016, 03:41 PM

I've had a off/on problem with my ABS light, last time it was the front drivers side sensor, the gap was off, pulled it out, cleaned and put back in, no light since.

Here is a link to a troubleshooting guide
http://www.meritorwabco.com/MeritorW...ent/mm0112.pdf

Page 77 has the 798 code.

Ask the service manager if they have check the resistance on the circuits as described in the manual.

Bendix has a pretty good diagnostic system. Even on my 2002 I can retrieve the blink codes. The new systems have an interface to laptop that have more capability to diagnose so my guess is that your shop is providing you accurate diagnostics. Have them show you this, have them run the diagnostics while your standing there. It would be hard to fool you then.

DJLind · 06-02-2016, 04:36 AM

Thank you Jim, both for your advice and the link to the manual. I breezed through it, and beyond the code descriptions, it is full of interesting (to me) information about the ABS system. I'll be working with the shop to get the right fix in place.

jacwjames · 06-02-2016, 06:58 AM

Yup, once you look at the depth of info that can be obtained with the diagnostics it gives you the ability to have a conversation with the repair shops. The more intelligent you sound the less like they will be to try to pull one over on you.