speedo

My factory speedo has died. One day is started twitching but still worked and just the other day it wouldn't work unless I was goin' 35-40+MPH. Now, it is dead. It will maybe, once in a great while, jump up and go back down. What should I check?

The gears for the drive, at the trans

Hey Mark...go back out to grandma b's house and get the sending unit out of the other tranny (the one that we took out of your car). On the sending unit there should be a 10mm bolt holding a metal plate that is holding the black plastic sending unit in the D/S (driverside) of the tranny. Once the bolt is out, pull the metal hold down off, then PULL STRAIGHT OUT ON THE SENDING UNIT!!!! Some slight twisting may be needed to get it out. Then reverse the process on your car. You should be able to get to it with the car (body) jacked up just a bit, so be very careful. And most importantly DO NOT CROSS THREAD THE BOLT THAT GOES INTO THE TRANNY!!! I don't have any spares of that little b@#$%, so watch what you do with it. You should be able to change it out right there at her house in a matter of 5-10 minutes.

Let me know if you have any problems with it and I can talk you through it on the phone.

Also, let me know how the car is running overall, I would like to know.

Jim B .

Hold on there before you start throwing parts at the problem!! A few VERY simple tests are in order first!

Drive at a speed where the speedo reads zero, like 25 mph. Does the odometer still work? If so, the speedo head is bad. Can also try giving the dash a good wack while it reads zero and see if it starts working. If so, again, speedo head is bad. Does the cruise control still work with speedo reading zero (remember cruise wont engage under about 30 mph)? If so, VSS and its harness is good. Is spddeo and odometer and cruise all dont work / start working at the same time, then look into the VSS, the drive gear, and the wiring harness.

I will look into all this when I go to and from work tomorrow. Thanks Jeff. BTW, I will be sending that 140MPH speedo to ya soon, I just haven't had time nor the extra moolah to do so. I will let you know when it departs from here.

Originally posted by Jeff K:
Hold on there before you start throwing parts at the problem!! A few VERY simple tests are in order first!

Drive at a speed where the speedo reads zero, like 25 mph. Does the odometer still work? If so, the speedo head is bad. Can also try giving the dash a good wack while it reads zero and see if it starts working. If so, again, speedo head is bad. Does the cruise control still work with speedo reading zero (remember cruise wont engage under about 30 mph)? If so, VSS and its harness is good. Is spddeo and odometer and cruise all dont work / start working at the same time, then look into the VSS, the drive gear, and the wiring harness.

Ok, well, it is working again. When the speedo wasn't working, at the same time neither was my PRC. It was actually working but would just keep blinking at me. So I switch it to auto and then back to firm and it stay'd on firm. Is the PRC and/or switch in any way associated with the speedo? I wouldn't so but I just gotta ask. Thanks for all the info. If this isn't in the FAQ and/or Tech Articles, it needs to be.

Edit: It is starting to act up again.

They seem to share the same ground # 902 at the lower center of the instrument panel on the right side.

Hmmm...I will have to check that. It should be ok tho, I'm sure the speedo head is just trying to crap out.

>Is the PRC and/or switch in any way associated >with the speedo?

yes the prc needs the vss signal to work.