Spedo & Odometer not working

[MrWinkey]

It stopped working on my drive in this morning. I havent been able to dig up my book yet has anybody encounterd this problem and what should I check first?



Do we use a mech spedo or an eletrical?



Thanks!

 

[Steiger]

It's electrical, at least it is on mine. There is a sensor but I think it is probably just a generator, the faster it turns the farther over the needle goes on the speedometer. I took mine off and put a cordless drill on the shaft to turn it and the speedometer still didn't work. Replaced it now it works fine nice and steady and no bouncing needles. If I remember right all you need is like a 7/8 open end wrench and unplug it. Hope I'm leading you in the right direction.

 

[1stgen4evr]

speedometer not working

This may be too simple but mine just unscrews and drops off from time to time. Never have lost it. It hangs on by the wires. Have you looked? Once the drive tang wore to the point that it would not turn the sensor. It isn't cheap.



And it is electrical. I am pretty sure that it is a pulse generator. The computer reads the input from the sensor. On the automatics, the computer uses that input as well as input from the TPS to determine the overdrive shift. Don't know just what it does for the Getrag transmission trucks. Someone with AllData service information can fill you in.



It is located right where the mechanical speedometer drive has always been on a transmission.



1stgen4evr

James McPherson

 

[dan brooks]

It may be something as simple as a bad connection: Mine quit working a while back. I cleaned the contacts and it has worked fine since.

 

[RoryTek]

Do you guys know if it is the same on a 2nd gen? Cause I have the same problem, and I was told the we get the signal from the rear wheel sensor.

 

[1stgen4evr]

same on a 2nd gen?

RoryTec I have a transmission (nv4500) from a 2nd gen and the speedo drive is on the tail houseing just like the Getrag. You do have a sensor on the rear as well. I can't tell you just how the inputs are used but as I mentioned, if you have a connection with a service facility where they have AllData, the information is quite complete as to where the inputs are and how they influence the output of the comnputer. Before I discovered TDR, AllData was my only hope in keeping my 92 running.



Love my Cummins



1stgen4evr

James McPherson

 

[Philip]

The rear wheel sensor is for antilock brakes. On our trucks it is located in the center section reading off of a serated ring mounted behind the ring gear.



But for the speedo problem. Check you conections over very well.

 

[MrWinkey]

Thanks!



I've not had a chance to check it out as it snowed like 2" last night and I didnt get home till after 10 pm. I'm going to try and check it out tonight or tommrow!!!

 

[dpuckett]

Check not only your connestions, but the round parts of the truck end (female?) of the connector itself, and see that they are still round. I had one get a little out of round, and it would make the needle jump all over, like to 90 in 4th w/4. 10s. Made for killer MPGs, by the odometer, though. I took it all apart, and took a pari of Vice Grips to it, anf GENTLY pressed it together a little, then put it all back together, and it has worked so far so good for almost 2Kmi.



Also check the gear box (if you have one- 90* box) to see that it turns. Also check the shaft on the end of the speed sensor, and the box (again, if applicable). Then check the driven gear inside the transmission- takes a 1/2" wrench t take off the Y-hold- down thingie- and see what kind of shape it is in. Then look at the drive gear on the transmission output shaft and see that it isnt worn out. Had a Ford that was one time. AMikonis knows about driven gears that self destruct.



Daniel

 

[HonkinDiesel]

My fix

A couple years back it happened that my speedo started doing the funky bounce thing.



I can recommend that once you check out the wiring and sender located on the driver side of back end of the Getrash (you will see the wires running to it), is to check that lousy yoke nut located on the back end of the transmission and U-joint. My yoke nut kept falling off (I hate when that happens!)



I found that even though I tightened it on to rated torque, it still loosened off and the speedo did the funky thing again! I talked to a local transmission shop here and he said its a very common thing on this truck/transmission combo. The fix was to take the nut off and dimple the face with a punch and hammer so that when you torque it on it bites into the surface (sort of like a star/lock washer effect). And the other thing he recommended was to use a bit of lok-tite thread lock. I did both and have not had to look at it since



My 2 cents. Good luck on your situation! Let us know how it goes?

 

[TMWeber]

I had this happen 3 times on my 93. The speedo needle would skip/bounce then one day no speedo, no odometer. Mine was the speed sensor (if my memory serves me). It was located in the transfer case. I just unpluged the electrical connection, unthreaded the nut and put the new one in. I told the guys at DC the problem, they gave me the part (actually I had to buy it, it was fairly cheap-$25. 00?) and told me where to find it on the truck. Hope this helps and I diddn't just confuse you.

 

[bgilbert]

TMWeber, do you have the part number for that speed sensor? I have the same problem as you on the 91, troubleshooted it, cleaned super good, dielectric grease etc, still same problem. I didnt know it was cheap, heck I'll get one if there still available. Let us know if you or anyone else has the part number, thanks. Bill

 

[Greenleaf]

My truck takes the 05252438



-S

 

[EZGZ]

Mine had a extra gear reducer attachment and the gears finaly wore out. ( Tire size compensator I guess).

I went to dealer parts counter and the paarts fish showed that there were 3 choices of gear reducers. It was expensive and I just bought the repacement sensor part only.



Checked it against a GPS on the dash and it was only a couple MPH off so let it go at that. Sure was nice to have my cruise control back.

My truck had some smaller tires on it when I purchased it????