I've got a 91.5 truck...has the electronic speedometer. Can I change this out for a mechanical one....if I can find one? The speedo, odometer, and trip meter all quit, however the cruise and the o.d. all work fine. I looked in the sticky and did what was suggested there but to no avail. Must be electrical problem.

Thanks

 

Overdrive will not work if you do away with the electronic speedo. ( unless you handle overdrive by a toggle switch, or aftermarket pressure switches on the tranny.)

 

I figured something wouldn't work. Speedo shop guy says he can fix mine for 200.00! I thought I might find a cheaper solution.

Thanks

 

Find a used speedo head if thats the problem. Its either a wire problem or a speedo head issue. If the Vehicle Speed Sensor ( VSS ) was bad, then overdrive would not work. Your PCM needs a speed signal to select overdrive. Or so thats how I understand things.

 

Yeah "wanna" told me once before it was a head issue. The VSS is new. I did try all of the salvages around here but nobody had one. I might try flea bay, or the classifieds.

Thanks

 

scratching my head now. If od is working, and cruise is working.....I'm wondering why won't a mechanical speedo work? I've probably been up to long

 

Because a mechanical speedo can not " tell " the pcm what is going on. The speedo signal travels through the pcm and then goes to the head unit. The only year with the mechanical speedo and the cummins was 89 which had no pcm, or overdrive. The vss signal talks with the throttle sensor and as a pair they decide the overdrive shift via the pcm.

 

Gotcha....So I wonder what years would work? Any ideas?

Thanks

 

Gotcha....So I wonder what years would work? 90 thru 93?

Thanks

 

I'm sure glad my crew's donor was a 89.....

Good luck.

 

Aren't there some older 2 piece speedometer cables that drove the older 80's cars & trucks cruise control units? I know GM used them. If so, then why not mount the VSS under the hood and feed the upper cable from it to the speedometer head? It might require an adapter of female to female threads if available. I cant remember how the intermediate cruise control was connected but I think it had 2 female connections.

 

Thanks for the idea....however you might as well be speaking a foreign language. I think I've located one from a member here on the forum. I found a salvage and I can have mine rebuilt for a tad more than what they wanted!

Regards

 

there were some years of dodge products that had a speed sensor with a cable hook up on them i think some of the early front wheel drive stuff maybe i will check into it and get back

 

SOME of the '86-'89 Dodge trucks have a speed sensor (VSS) wired in at the speedo head unit.
It is a 2 wire unit, and I believe, in the 1989 diesel trucks, it shuts the grid heaters off above a certain MPH.

I have an old '89 out here I fully intend to dissect the speedo and wiring from for this very reason, to find out the routing of the VSS on the speedo.

Mark.

 

Dodge Dakotas prior to 1995(?) have this set-up, but they also had a @ 1/2" screw on connector for the speedo cable.
Dodge Fullsized pick-ups used a @ 7/8" one.
Not to worry though, certain late '80s Jeeps used an adaptor sleeve on THEIR VSS' that will work on the Dakota sensor to adapt it up to the fullsize cable end.

Mark.