I'm having a few problems with my 1999 Dakota 4x4. I thought the problems were unrelated but after searching the forum I think they all come down to a speed sensor.
1) ABS light is on, and I haven't really tested the brakes but I believe they will currently lock up rather than pulse stop.
2) Speedometer stays at 0 until I reach about 20-25 mph, then works fine for anything over 20-25 mph.
3) (Just started) transmission will not shift from 1st to 2nd until 3k-4k, (winds up excessively even if I'm not hard on the acceleration).

From what I've read a speed sensor could be the problem for all 3 of these conditions. I haven't checked (paid attention to) the speedometer since I started having the trans problem, but my guess is that the speedo won't work now until a bit higher, causing the trans not to shift until it gets the signal that it's time to.
So, here are my questions...
1) Does this sound like a speed sensor problem, or is it more likely something else?
2) I believe that there are more than one speed sensor on this truck, which one would cause all 3 of these situations (if there is one).
3) How hard is it to change a speed sensor? IOW, could a shade tree mechanic do it without alot of special tools?

Thanks in advance,

DDM

 

really easy, a 13mm and 14mm deep socket or combo wrenches are all that is needed. The sensor is bolted to the top of the rear diff housing.

 

Thanks DodgeMech. That was it, I stopped by the parts place on the way home and bought the sensor (and a Haynes manual). The sensor was about $24, and it took me all of 15 minutes to screw out the old one and replace it with the new one. The old one was coated with small bits of metal on its magnetic end, so it's most likely still good, but I went ahead and replaced it anyway. She shifts fine now.
The ABS light is still on, and the speedo still has the 20 mph minimum problem, but after more researching yesterday, I came to the conclusion the these are on some other speed sensor. I may get around to replacing it later, but for the time being it doesn't seem to be causing any real problems.
I guess the small metal bit build up indicates that it wouldn't be a bad idea to have the trans fluid replaced.

ps.
My sensor was located on the bottom of the rear diff housing, which made it that much easier to change out. I lost a little fluid during the change because of it, but that's a small price to pay for easy access.



Thanks,

DDM

 

OOHHH, you replaced the trans output speed sensor. Thats a start, now replace the ABS speed sensor located all the way in the back of truck on top of the rear differential(rear-end). Then disconnect battery for a few minutes to clear out fault----This all assumes you dont have 4 wheel ABS in thaty case it could be the ONE in the back or one of the TWO front ones(one at each wheel)

 

Doh, I can't tell the difference between a rear differential and a transmission [sm=smiley29.gif]. But you figured out what I changed. I'm not sure if it's 4 wheel ABS, but I'll check this weekened, and take the appropriate steps. It will be nice to finally drive my truck without any warning lights on, and not to mention, have ABS again.

Thanks again DodgeMech,

DDM

 

After replacing the speed sensor is there a need to take the vehicle to a mechanic to reset the computer for the new sensor or can you just unhook and rehook the battery?

 

you can reset it yourself, just unplug the batt for a minute or so and re attach the batt cables. if there is an any aftermarket equipnment, such as winches or amplifiers, unplug them first. they tend to hold current in their curcitry.

 

ok i have a 2000 with the same shifting problem. i'm just having trouble locating where the sensor is!!!! its not in the same placeis it?