The speedo and the cruise control in my 96 mk3 5.2 V8 Ram Wagon have both stopped working. I take it the cruise control works off the speedo but I can't figure out why the speedo won't work. I pulled off the dashboard expecting to find a snapped speedo cable but couldn't find a speedocable at all so the speedo must be electronic. I tried a Haynes manual but it wasn't very helpfull with either thewiring, the speedo or the cruise control. I replaced a speed sensor on the rear diff, that didn't work, seems only to be for ABS. A tried tracing wiresaround the engine bay, I could only find a snapped but clogged vacuum tube on the passenger side and couldn't find any wires or anyclues from the cruise control unit which I believe is behind and below the passenger side headlight,I found that by tracing back a cable from the throttle.The only other symptom is that every so often the speedo needle jumps around the place before settling back to zero.

Has anybody any help or advice??

 

The problem is with the speed sensor circuit that runs to the back axle where you already replaced the sensor. Since the sensor is new, you have a break in the circuit somewhere. This sensor controls both the speedo and the cruise. Since you get an occasional jump from the speedo, it's a pretty safe bet to say that there is a break or short in the wiring somewhere.

 

OK, well I have a 92 Dodge ram van I went through the same problems. If you replaced the VSS and the one on the differential which controls the speedo, ABS and if it goes bad ,makes it run erratic too,I did replace all that but still had the problem untill I replaced th "speedo" which had a short in it. went to a junk yard got one all is well now. My ABS light went out, speedo normal ,van runs great.

 

I notice you said you replaced the speed sensor "VSS" butdid you really it is located on the transmission, the other is a second sensor on the rear differential ,that doesmake yourspeedogo crazy,ABS light come on,van run erratic if it goes bad. If it's not either one of those because you replaced those then you need to replace the speedo .I already went through all that .It's not the wiring ,if any wire was bad it would be the one jumper wire from your back passenger side frame to the top of the differential you can get one at a junk yard cheap.Good luck

 

Thanks guys! A bit long in response I know...

I've since left the country and gave my van to some friends in a rock'n'roll band when their Ram van died. They since brought it to a mechanic in LA who said it's the sensor in automatic gearbox, that there's a ring which the sensor reads and that this ring is out of allignment which makes it chew up the sensor. He's saying this will mean taking apart the transmission to fix the problem which will cost a few thousand. The autobox was replaced less than 4,000 miles ago but the vans been sitting for about a year and the box is now out of warranty.

So the question is now does this sound reasonable and if that is the problem, can I just fit an after market speedo to by pass the problem so the van passes the California SMOG test??

 

You can have the whole tranny rebuilt for less than that. I'd definitely go get another opinion.