digital speedometer question

The speedo in the 9C1 has not worked for quite some time. I took the unit out and cleaned the contacts as usually suggested, but that didn't help. So I borrowed the one out of my wife's L99 and it did not work either. I put the 9C1's into the L99 and it did work, but it showed the 9C1 mileage! So I have kind of a 2 part question here:
1. I was amazed to find that when I plugged the 9C1 speedo into the L99, it showed the 9C1 mileage. I would have thought that that little unit just said whatever the PCM told it to say, but I guess it has a memory? How does that work?
2. Since cleaning the contacts is not the issue here, what would you guys try next to make the speedo work? To be clear, the L99 and the 9C1 speedos work in the L99, and neither speedo works in the 9C1. The pins in the 9C1 dash are sticking out far enough to make contact.

The mileage is stored in the display module of the instrument cluster.

I THINK the speedo gets its signal from the VSS located in the tailshaft of the tranny.

Once again...I'm not 100% sure...been working on alot of "my idea" theory

http://shbox.com/1/vss.jpg

It should throw a code if that helps

I figured out how to make my speedometer work.
If anyone has the same issue where the speedo is intermittent and the contacts are not the issue, you can fix it with the following method:
Wrap your left arm around the left side of the steering column, pull your left fist toward you until it is against the steering wheel. Then instantly slam your fist onto the dash just under the speedometer, and it will come back to life for a few days or hours or minutes at which point it will go out again. At that point, repeat the process and you will be good to go for another undetermined amount of time.

FUN-9C1 wrote:

I figured out how to make my speedometer work.
If anyone has the same issue where the speedo is intermittent and the contacts are not the issue, you can fix it with the following method:
Wrap your left arm around the left side of the steering column, pull your left fist toward you until it is against the steering wheel. Then instantly slam your fist onto the dash just under the speedometer, and it will come back to life for a few days or hours or minutes at which point it will go out again. At that point, repeat the process and you will be good to go for another undetermined amount of time.

LOL. Great write up. Should I make it a sticky?

Lmao

IMPALADAKID wrote:

FUN-9C1 wrote:

I figured out how to make my speedometer work.
If anyone has the same issue where the speedo is intermittent and the contacts are not the issue, you can fix it with the following method:
Wrap your left arm around the left side of the steering column, pull your left fist toward you until it is against the steering wheel. Then instantly slam your fist onto the dash just under the speedometer, and it will come back to life for a few days or hours or minutes at which point it will go out again. At that point, repeat the process and you will be good to go for another undetermined amount of time.

LOL. Great write up. Should I make it a sticky?

I've never read anything else that is more sticky worthy!

Hey I fixed it for real this time, no more slamming the dash (that worked less and less lately)...

Something in the white module that the display module screws onto was the issue. I swapped the white modules between the L99 and the 9C1 and now the 9C1 displays perfect and the L99 does not. I kept the gages and display module with their original cars.

Pretty easy, took me about an hour learning as I go and not rushing.

Thought that might help somebody.

Any pics of what you speak of? Just for future reference?

Sorry, I didn't take any pics, but it's the big white plastic module that the speedo display module screws onto that I replaced. It's held in by 2 screws on top and 2 on bottom.
The gages pop right out of it by hand so I kept the 9c1 gages with the 9c1. The L99 oil gage has been really an idiot light all it's life and was a little jerky being an actual analog gage, and I liked the 9C1 temp gage better.

If you want to try it and need more detail let me know and we can talk on the phone.

That's fine. I'll give it all a shot.

Thanks!

Be aware, too, after you take out the four screws it's held in pretty snug by the electrical connectors behind it. they are on the bottom. Pull hard on the bottom and it will come out.

Thanks for the heads up.

I don't want anything (else) to break.