Funcie

I recently purchased a 1993 Pickup 5spd 2.4L 180K miles and Im having problems with the speedometer. I have searched and found other people with speedo problems on this site and others but mine appears to be a lil different.
I drove the truck to work this morning and the speedo was dead for 15 minutes then sprung to life and operated normally after that. I got to work and it sat for an hour or so and then when driving it again it did not work for a few minutes then operated normally. It has been doing this for a few weeks seems to working less as time goes on. It also seems that the longer the truck sits the longer it takes for the speedo to kick on again. All the other gauges work (including odometer) while the speedo is dead. Any thoughts...I looked at the prices on the vehicle speed sensor on the tranny and it was kinda expensive so wanted to make sure that was the problem before forking out the cash. I would greatly appretiate any help.

fdp101452

I had this problem in an old Jeep one time, it was the needle hanging up on the inside of the speedo head. It was a mechanical speedo and I dont know if yours is or not, but anytime it quit working I just smacked it with my hand and it worked everytime.

Funcie

I'm fairly certain its electronic not cable driven. I think they switched to electronic in 92...correct me if im wrong.

RBX

same issue in my 22re '92.
Mine is usually dead. I believe they are electric. I have no solution since i rarely drive the truck, it hasn't really bothered me much.
I'll be watching your thread to see if you find a solution, someone will chime in.

Good luck,

scope103

4wd? You probably have the electronic speedometer, and the sender (VSS1, in the back of the transfer case) is dying. Do you have cruise control? When the speedometer doesn't work, is the cruise control out with it? Almost certainly VSS1.

a) It seems to be a common problem reported on this list (after all, these are not brand-new trucks), b) the part is not cheap (about $181 at RockAuto - pull yours first, so you can match the photograph). Note that you keep your nylon gear, and replace the rest of it.

But I had those symptoms about 8 years ago, and replacing VSS1 cleared it right up.

The MAN

if the odometer still works while the speedo stopped working, it's the gauge itself that's dead, NOT the sensor

the odometer is also driven by the sensor so if the sensor is dead both should stop working.... this isn't the case, so it's quite obvious that the gauge is bad... this same exact scenario happened to my friend's 240SX years ago... he replaced the cluster and it fixed it

Funcie

scope103 - Its is a 2wd without cruise control...sorry forgot to put that in the original post. Do you remember if your odometer stopped working when the speedometer went out?

The MAN - Thanks I wasnt sure if the odometer was tied in with the VSS or not.

scope103

If you have an electronic speedo, you DON'T have a cable, and there is no other way for the odometer to work. In my case, I didn't wait until it crapped out completely (it would drop for 1-30 seconds and then pop back up, taking out the cruise control with the first drop), so I never tried to determine that the odometer stopped too. But how else could it be?

So if your odometer is working and the speedo is not, then it is not VSS1. Your odo is getting a signal from somewhere.

The MAN

yup... odo and speedo are run off the VSS1 signal... if both don't work, then it's the VSS1 that's bad, if one of the two works then it's not VSS1 but the instrument

Funcie

Looks like Ill be getting a new or used cluster. Thanks for the help guys!

The MAN

good excuse for an SR5 cluster upgrade

frozenrice

Good information in this thread. I just encountered the exact same problems with my speedometer as the OP. I have the same truck except with an automatic transmission. When these speedo/odo problems started i also encountered problems with the transmission intermittently not shifting properly. Is this a coincidence or related to the speed sensor too? I don't quite understand how the ECU processes the transmission shifts.

The MAN

if the tranny is electronic, then yes, the speed sensor affects how it shifts... the signals first goes to the ECU then from there the ECU outputs another signal to the gauge, and obviously the ECU also controls the shifts

frozenrice

Electronic as in electronic shifting? I wasn't sure if the signal went from the sensor to the gauge to the ECU or to the ECU first and then the gauge or if the signal was split. I just wanted to rule out a bad ECU before getting a new sensor. Am I on the right track here?

frozenrice

Okay I'm stumped now. I got a hold of a new speed sensor. Installed it and nothing. Speedo and odo still don't work. I checked for voltage on the wires from the harness and I'm getting just under 12v. So I'm not sure what to do next. I didn't drive it around enough to tell if the transmission issue would act up again. It seemed to work fine as usual for the few blocks I did drive it though.

frozenrice

Replaced the cluster yesterday (SR5 upgrade since I was at it) and still nothing...... FFFFFFFUUUUUUUU!!!!!!
Next on the list....ECU?

RBX

That stinks.

The MAN

time to check wiring

frozenrice

I'm afraid that my electrical skills fail me. I should have paid more attention in science and physics during school LOL.
I'm trying to figure out the electrical diagrams and I'm lost. Does the signal from the VSS1 go to the ECU first and then to the speedo or is it the other way around?. Like I said, the other day I tested the wiring (assuming I did it right) and got just a little under 12v at the leads on the connector that goes to the VSS. It would appear that the VSS is getting power at least and assuming that the new VSS that I got is actually working properly, I'm assuming that the signal is sending properly. The only other theory I've got right now is that the ECU is not processing the signal properly and not relaying the info to the speedo.

scope103

There are three leads to VSS1; two of them provide battery (gnd-12v) voltage, and the third is to the speedometer and the ECU.


Before spending the money on the sensor, I tested everything upstream by putting a signal generator into the signal lead, to see if the speedometer needle would deflect. (you can see the results in the drawing) Of course, that doesn't do you much good now.

The electrical diagrams I have are all for the "mechanical" speedometer, in which VSS1 is just a reed switch, inside the cluster. So I can't even give you the color of the signal wire at the cluster (though it is almost certainly grn/red, as on the sensor itself).

Good luck!