Speedo gone nuts!!!

[ERMiles]

I've had a nagging problem with my speedo jumping around for many months - tried replacing sensors and cleaning contacts,etc. The CC has never (since I got it 2 yrs ago)worked. Now it has developed a new symptom. At idle, it jumps around going up as high as 60 mph! Obviously the sensor isn't doing anything when the truck isn't moving so I'm wondering if this is a clue to where the problem might be.

Any ideas???

 

[ETOBICOKE]

Possible Wiring Problem?

Sounds like a ground problem, may be a damaged wiring harness shorting out or a bad ground on another electrical component trying to ground through your speed sensor or speedometer. You will need a volt meter and ohm meter to trouble shoot this problem. With the engine running, disconnect the speed sensor, there should be no voltage present at the speed sensor connector (the part you disconnected). If as I suspect, there is voltage present you will have to check each conductor for resitance to ground. You will need to unplug the speedo and engine controller to do this. By the way the speed sensor shares a common sensor return with six other devices, located all over the engine and this is most likely where a short will likely be found. Get your hands on a service manual, it has all the wiring diagrams and information that you will need to assist you. If you don't have one send me an email.



Neil

 

[Speedo]

Speedo gone nuts...

I am not!

 

[CAROLINA CUMMINS]

Speedometer

Yep, mine has been doing it too for a couple of months. I hope you get yours fixed. Mine dropped from 60 to 0 and then back one day I'm going to have to get under there and find the problem. Sometimes it just jumps a little but It gets troubling after awhile.



Good luck Steve

 

[ERMiles]

Neil;

I checked for voltage at that connector and I got about 4. 5 Volts. So it sounds like there is a bad ground somewhere. I didn't have time to disconnect the wires at the speedo but there was a resistance to ground on both leads at the connector end. I don't have a service manual but I did get pages AD41 & AD42 form another member which I got to try to trace the wiring path from the speed sensor to the cruise control. But it doesn't show the sensor or the Speedometer. Any help you can provide that will assist me in finding those ground points will be much appreciated.

Ted Miles AKA "Smiles"

 

[Midnite]

Re: Speedo gone nuts...

Originally posted by Speedo

I am not!

I dunno... when you started talking about having the DTT stuff installed, you kind of had a funny gleam in your eye!

 

[AlK]

CAROLINA CUMMINS,

If the speedometer only acts up while you are driving, then what I would recommend, remove the speed/distance sensor clean the mechanical parts and also use some electrical spray to clean the electrical connection on the speed/distance sensor.

---

Al

 

[ageorge]

Speedo woes

Mine (93) was doing the same thing. I was going to put in a new sensor, but found everything started working right after I changed the output seal on the transfer case. When I changed the seal, I took the seal housing right off and cleaned everything up real good. It has been 3000 miles since, and no more problems. Worth a try. Al

 

[Forrest Nearing]

mine has been messed up ever since a road rage incident in which I pounded on the dash board w/ my fist... at first the needle just wouldn't move... but I found if I pushed up on the dash it would work, so I wedged something between the column and the dash and that fixed it for a while, but not it bounces every now and again (when I go over bumps) it's annoying... guess that's what I get for my little temper tantrum!



Forrest

 

[Forrest Nearing]

JUST FIXED IT!

well, this post inspired me to yank the gauge cluster and figure out what the deal was w/ my erratic speedo... it had been getting worse, and I didn't want to drive 1500 miles in the middle of the night w/o a speedo... too many speed traps going through little towns and such...



anywho, through some trial and error, I traced it down to a bad connection where the circuit board plugs into the back of the speedo!



not sure HOW the connectors got ovaled out, but they did... looked as if there was only one that was not contacting... maybe two... I simply crimped them down so they would be tight on the contact post and wallah! speedo works now!



now if only I knew why my cruise doesn't work (and hasn't for as long as I've owned the truck! )



Forrest

 

[ERMiles]

Forrest - You've inspired me, I'm gonna pull my instrument cluster and check that board. I assume the only way to access it is to pull the dash apart. I, too have not had the CC work since I got it. I was assuming that if I got the speedo working OK the CC would, too - guess not. Let me know if you tear into that one.

Ted (Smiles)

 

[Forrest Nearing]

not sure as my cruise has never worked as long as I've owned the truck



I'm not saying this is your problem, but it's worth a shot...



it's pretty simple after a little tugging and twisting on the trim panel... some philips screws, some torx screws, and you're in business...



it took me a little while to trace it down to that connection (by driving and wiggling the plug connections, etc. ) and I discovered that if I clamped down on the circuit board and "squished" it against the cluster, the speedo worked...



so I pulled it out and started taking it apart till I found something that didn't look right... took me a while, but then I noticed that the three female connectors didn't all look the same... one was very rounded and another was pretty round... so I just took a small screwdriver and crimped all three of them down pretty flat...



hope it fixes your problem!



Forrest