jumping speedometer needle

[MNmopar]

I did a quick search and didn't find anything about this particular issue, but if I missed a thread about this, please post a link and I'll check it out.

When I picked up my 89 spirit es turbo, I noticed that the tach was inop (would just read mostly random rpms while driving, usually "hovering" at certain spots), and the speedometer needle jumped all over the place when I first started driving the car after it sat for awhile. After about 5 minutes of driving, the speedometer would settle down and seemingly work correctly, but for that first 5 minutes or so, I had no idea how fast I was going.

I ended up picking up a guage cluster from Lengel when he parted out his spirit r/t for a great price, so I stuck that in to see if it solved anything. The tach seems to work perfectly now and the speedometer is better, but it still jumps around from time to time... could this be a ground issue?

I'm planning on re-soldering the contacts on the back of the original cluster, but I'm wondering if there isn't another issue too. I also have a weird blinker thing going on with the driver side blinker in the bumper. It's not blinking even though it lights up and the side marker blinks like a cheap hooker...? Anyway, I'll get to that later, but mentioning it just in case they could be somehow related by ground?!?

Thoughts?

[Shadowv4l]

I had the same problem, it was really bad when i layed into the throttle and would flutter in place. I replaced the throttle cable with a one-piece design and it fixed my problem. I also had an issue with my 94 shadow, the needle would jump to 120mph and then drop to zero while driving, i just cleaned the contacts and it fixed the issue. *Try this, when it starts acting up slap the top of the dash above the cluster and see if it changes the needle's behavior, if it does then it means the contacts are crappy on the back of the cluster where the round connectors are. ( I also had to do this do get my blinker indicators to work)

[Dodge Aries K]

I had a bad speed sensor do this same thing.

[Austrian Dodge]

sounds like a bad speed distance sensor

[RJ138]

Try cleaning up the connector to the speed distance sensor on the extension output of the transmission. I had a similar issue with the speedometer jumping and there was oil and gunk collected in the the connection to the sensor. I cleaned it up and it worked like normal again.

[MNmopar]

Thanks for the ideas guys, I'll try rapping the dash first (free) and then I'll focus on the sensor and possibly the cable. After giving the car my first good "once over" since I've owned it, I could definitely see the speedo connector being in need of a good cleaning...

[MNmopar]

^ RJ138, I finally had the time to mess with it, and that's exactly what the problem was... oil.

I cleaned out the plug and wiped down the connector and now it works like new again. Good thing too, because I couldn't get that little punk of a sensor to move at all even after taking the screw out...

[cordes]

A great way to trouble shoot this is to see if the cruise will work. It won't work if your SDS is bad in some way. If the cruise works flawlessly while the needle is jumping around you'll at least know the signal is good to the SMEC/SBEC.

[RJ138]

^ RJ138, I finally had the time to mess with it, and that's exactly what the problem was... oil.

I cleaned out the plug and wiped down the connector and now it works like new again. Good thing too, because I couldn't get that little punk of a sensor to move at all even after taking the screw out...

I'm glad I could help. I agree the sensor can be a bugger to pull out at times.

[MNmopar]

A great way to trouble shoot this is to see if the cruise will work. It won't work if your SDS is bad in some way. If the cruise works flawlessly while the needle is jumping around you'll at least know the signal is good to the SMEC/SBEC.

that's good to know, thanks for the tip cordes!