I replaced transmission on my truck with a used one, and now I have no speedometer (and odometer)

Is it mechanical on '99s or electronic ?

 

It is electronic and has nothing to do with the transmission. It comes from the sensor in the rear axle. better check your wiring and any plugs that you may have unplugged in the repair.

 

There is a speed sensor on the tranny tail shaft. It has something to do with the speed reading, but it is not clear to me what it does. I have heard that it merely tells the rear speed sensor to heed the signal it is receiving, and I have heard that it works up to 20 mph, then the rear speed sensor takes over. Either way, that is probably your problem.

Chris

 

The manual trans sure doen't have one.... interesting.

 

I just know because I replaced both of them while trying to track down a cruise control problem.

Chris

 

I checked all the places, still no odometer and speedometer. There is a 2 wire sending unit on top of rear differential, and all the other connections are fine.
I even replaced the sending unit on rear bottom of transmission.

Any hints of where to look ?

Thanks

 

My Superlift Truespeed tied into a wire at the Anti Lock Brake controller.

It was a wire that came from the back of the tranny.

The instructions said to splice into this wire at the back of the tranny, but the guys that installed it had done so many, it was easier to splice into the same wire at the brake controller.

Sorry, I have no idea what color or anything, just where the splice is.

Gives you somewhere to look at least.


phox

Oh, the truespeed corrects the speedometer/odometer for bigger tires, just in case you weren't familiar.

 

See it on the tail shaft? It is unplugged, and the plug is hanging just below it.



Chris

 

Stamey, that's exactly what I replaced.

Interesting view you have there, remembers mine, same view 2 days ago.....

I've got to study on this, I will get back tomorrow.

 

I have an interesting question. If the transmission on the automatic has the sensor that the rear compairs to where is the sensor on the manual trans truck. It is not on the trans.

 

Pretty sure the manual tranny trucks just use the sensor on the rear pumpkin.

Auto equipped trucks must use the 2 in conjunction with one another to figure shift points.
Computer compares the output of the two to shift.

Why one or the other would cause the speedo to quit doesn't make sense though.

You'd think the speedo would just use the one on the pumpkin, but apparantly it doesn't work that way.


phox

 

you may want to check all the fuses too...I did a replacement and couldn't get my cluster to work in my tahoe and it was just one of them pesky fuses

 

I did the Gauge Test as per instructions and all the gauges and lights work fine. The cluster has no problems. Traced all wires and saw no sign of problem.

I will try to go to ******* today and have it scanned....

I believe the speed has something to do with performance and shifting of the truck, since it feels different than before.

 

Scanned ECM at dealer and found out rear sensor was bad, they asked $ 110 to replace it.....

Wen't home replaced sensor with one from my "spare" truck .....
Now I've got speed back.

 

I got my rear speed sensor from ChryslerPartsDirect.com, because I don't want to deal with the closest dealer to me.

Chris