Hi,

We just bought a '91 Ram 250 for my 17 year old niece. It's got a 360, auto with overdrive.

The red brake light is on, but barely visible. The RWAL amber light is on too. The speedometer doesn't work. The odometer wasn't working when we drove the truck home, but started working after I pulled the plug on the sensor on the top of the differential and cleaned it out.

After reading here about this rear sensor fixing the speedometer/odometer/RWAL light/brake light problem, I replaced the sensor.

Still no speedometer.

I also tried what I'd read others have tried and disconnected the RWAL box completely - still no speedometer.

Last night we tested for codes from the RWAL box behind the glove box and what we get is 4 flashes, pause, 4 flashes, pause, 4 flashes etc.

IF I'm right and that's a Code 4, indicating the closed RWAL valve switch, would this keep the speedometer from working or is there the possibility that the transmission speed sensor or the cable coming from the trans sensor is bad?

Also, the fuel level gauge doesn't work, but I'll save that for another thread.

Please help get the girl's first car working!

Thanks!

 

don't create another thread for you fuel sending unit. the speed sensor in the trans could be bad or just need to be cleaned like the one on the rear axle. the sending unit may just need to be cleaned and is not too hard to remove from the tank.

 

Thanks, Crazzywolfie, I'll keep it all in one thread.

I did unplug the wire coming from the transmission sensor and I cleaned the plug. I actually did that a few days ago. I should have said that in my first post.

Should I remove the whole sensor from the transmission and clean it or were you just talking about cleaning out the plug?

 

i was thinking take the sensor out of the transmission and clean it. cleaning plugs sometimes helps but not always.

 

Ok. I removed the sensor on the transmission and cleaned it and cleaned the plug on the cable too.

I also removed the plug on the valve that's tucked into the frame rail on the driver's side, the RWAL valve I think, and cleaned that and plugged it back in.

The brake and RWAL lights are both still lit and the speedometer still doesn't work.

I also was able to lock up the rear tires while I was testing for the speedometer. So there's no rear anti-lock.

 

The RWAL system on my truck has never worked since it left the showroom floor. This was a very poor first attempt, by manufacturers, at anti lock brakes. Most people just unplug the module behind the glove box.

If you can't find a flaw in the wiring the speedometer sensor or the display are bad. I have not seen any way to trouble shoot this system other than parts replacement. The sensor is more often than not the problem and it is the cheapest of the two.

 

is your park brake pedal sitting a bit low because that could cause your brake like to come on if your brake fluid level is where it is suppose to be. you could use something to tap both wires that come off the speed sensor together to see if the speedometer works i think.

 

I'll try all of that tomorrow.

We're not too bothered about the RWAL not working, but we need the 17 year old girl to have a speedometer.

Thanks!

 

i wouldn't worry about the RWAL either. you get use to it. i locked up the rear brakes the first couple of times i drove my 81.

 

Wolfie; You should put that speed sensor info along with the explanation of how to use it in the "1st gen do it yourself" thread.