Hello all, I've been a member here since 2004 but this is my first post, lol. I'll try to add as much detail as possible. I know there are a ton of threads about this but here's another lol.

I bought this truck last weekend, it has the brake and ABS light on and no speedo. Occasionally it will beep and the air bag light will come on for a brief second but never stays on. It also will randomly stall at idle. They tell me it sat most of this past winter until I bought it. It had a P0501 (VSS), 0573 (Cruise control high), 0344 (Camshaft int) and 0507 (IAC revs high) when I picked it up. Cleared codes, drove 3 hours home and speedo randomly worked but it shifted very well and only stalled one time when I stopped at a stop light (3 hrs was mostly highway driving). Since it had VSS and CPS codes I changed those 2 sensors, (VSS being the one in the diff not the trans). I removed and cleaned throttle body, removed fuse panel and checked all connections under it, removed ABS connections, removed wire harness connection under drivers side fender well and checked connections that come from rear speed sensor and visually checked the rest of the harness from this connection to the sensor, cleaned battery posts and grounds, removed diff cover and checked all teeth for sensor and checked C clips/all gears, (all of which were good). None of this has helped with the speedo or lights that are on and it will stall at idle more frequently. The stalling I originally felt was either the IAC or EGR but now I'm not sure, I feel it has more to do with the vss/abs/brake stuff. None of the codes have come back.

What sensor controls the speedo? I've read its ABS sensor in the diff and also read its the output sensor in the trans. Can anyone verify which one it is? The air bag light randomly coming on for a split second is what made me start looking for wire faults, to which I've found none so far. I'm not a big fan of throwing parts at it, I'd rather diagnose properly first and save my money. Does anyone have a link to any wiring schematics for this truck? Thoughts on it all?

 

So I stuck our scanner on it at work today. Check out the attachment. FCM fubared you think? Keep in mind that everything except for the speedo works on the truck.

 

Could be PCM is bad.

Speedo is read off the ring gear in the differential on all 3rd Gen Rams...

 

So I drove it for a bit yesterday, check engine light finally came on. Had 2 codes, 37 - rear sensor signal erratic and 52- rear dump valve solenoid open. Did the troubleshooting as per the service manual for both codes, (well for code 53 - rear dump valve solenoid shorted, as service manual didn't show a code 52). for the 37 it tells me to replace the "controller anti-lock brake" and for the 53 it tells me to replace the "controller anti-lock brake module". I'm going to assume they mean the module not the whole control unit?? I'm going to try and find a know good used module before shelling out $$$$ on a new unit.