Archived No speedo, revisited

[pwerwagn]

Ok, I replaced the abs/rwss sensor on the diff saturday. It didnt fix my speedo not working and my abs light still on. I cant find another sensor on the x-case or trans. What else could have happened? Yesterday when I was leaving the lake, I took the e-brake off and the speedo stuck at 10mph for a while, and when going down a hill it jumped to 80 for a second. If I do the trip meter reset thing (hold reset in with key off, turn key on and let go of reset) the speedo goes up with the tach and rest of guages. I also checked my wiring, and it looks good up to the gas tank, where i cant see it anymore. What else to check?

 

[pwerwagn]

no answer?

nobody has any suggestions?

 

[Kirwin]

Vehicle speed sensor

On some trucks there was a speed sensor that screwed into the tailstock of the transfer case or transmission. This was used on some trucks that didn't have full ABS. I'll take a look at my 97 when I get home and see if I can find it. I believe that you will get an ABS light if either of these inputs are lost. As well as if you loose the brake light fuse. Have you checked all the fuses inside the truck? Ken Irwin

 

[joeyou]

Have you checked the speed sensor wiring?

 

[Kirwin]

Speed Sensor

There is a speed sensor on the tailstock of the transfer case on my 97 its located in a 1. 5" hole where the shaft extends out of the tailstock just forward of the first u-joint on the rear shaft, kind of rotated up toward the top of the transfer case. Hope this helps. Your truck has a different dash than mine so that may or may not help you. I don't have a service manual for your year Ram so I can't tell you what drives the speedometer in the dash.

 

[pwerwagn]

I checked the RWSS wiring as best as i could. I pulled off all the tape, and the loom and it all looked good. It doesnt look like i have a sensor on my tailshaft, Kirwin. but thanks for checking for me. I figured I would have one, but I looked all over for like an hour and couldnt find one. HMmm, maybe I'll check the fuses. Why is it I never think of the easy stuff? I just figured it wasnt a fuse because it was intermittent when it quit working.

Oh, by the way, the sensor I got is some new improved unit that also has a longer pigtail to make it work, and the plug is 180* from the position of the old one. any body know why?

 

[Kirwin]

The answer ( I hope)

OK Pwrwagen, I checked the service manual at my friendly Dodge dealer (thanks Dave) and the 98 is indeed different than my 97. If you look under the speed control system (don't ask me why they chose to put it there), it states that the Vehicle Speed Sensor has been eliminated for 98. The Rear Wheel Anti Lock Brake sensor sends a signal to the Rear Wheel Anti Lock Brake Controller. This controller develops a signal that is fed to the instrument cluster, speed control system via the PCM, and subsequently to the speedometer to indicate speed. If the instrument cluster tests good Dave suspects the fuse for the RWAL brake controller. Note that some functions of the RWAL controller are testable with the DRB scan tool. If you are friendly sometimes your dealer will use his scan tool to tell you what is wrong so that you can get the correct part. I didn't make a copy of the Service Manual but probably could if you need it. Hope this helps you in your troubleshooting. Ken Irwin

 

[pwerwagn]

Thanks Kirwin!

Man Kirwin, thanks for the help. I didnt expect anybody to go to that much trouble! Anyways thanks immensely. I will have some time with the truck this weekend (I "punish" myself during the week and dont drive it) so that is the first thing I will check. I assume the RWAL fuse is with the rest of the fuses on the left side of the dash? Thanks again, I really appreciate your help!

 

[boydo]

You may want to service your rear diff to make sure the reluctor wheel is in good shape. My speedo read 0 but somtimes jump up - not long after heard a bang in rear end. It was a broken spider gear that had damaged the reluctor wheel - the bang, that was a chunk of spider gear travel between my pinion and ring gear distructing every thing in there. So it's worth having a look because my lazyness on the subject(2 days) cost me $ 4000. 00 cdn.



Good luck, Bret.

 

[pwerwagn]

Fixed!

Ok, I got it fixed thanks to Kirwin. It was the fuse. Kinda weird, as it was intemittent. I figured the problem was in the diff, because of the intermittent. Actually, the fuse was blown. The previous owner didnt want to buy a fuse I guess, so they wrapped the blown fuse with copper wire!!! So, basically no fuse. The copper stopped making good contact I guess, because when I pulled it out and put in a new fuse, it fixed it. Thanks again guys for all your help.

 

[y-knot]

I also spent much time looking up your complaint on my "Mitchell On-Demand" program. Your 98 is slightly different then my '97, plus you have a manual trany, here is what I found out. You have no vehicle speed sensor, instead you have a rear wheel speed sensor that sends it's signal to the Controller anti-Lock brake (CAB). The CAB then sends a signal to the PCM or Power train Control Module to indicate speed and distance traveled.

There are diagrams that will help locate this units and also give wire colors and values at connections. Check all wires for condition and connection. Good luck.

 

[pwerwagn]

Thanks Y-Knot. I appreciate all your guys help.