Speedometer shows 00's

[herc795]

I have a 1990 and the Speedometer shows zeros, cruise control inop, and service ride control lite on. Does anyone know where I should start to troubleshoot.
Thanks

[-=Jeff=-]

all that not working.. sounds like the VSS (tail of Trans)

keep in mind the 1990 VSS is hard to find, but a 1991 will work with a connector change on the harness

[WVZR-1]

Don't rush to buy parts - check the connector at the VSS first - I'd probably check the VSS by removing and spinning with a rotary device.

With the SRC and the cluster out it's certainly VSS or the circuit I'd think. If you still have the Delco Bose - does the SCV still work? That would be very unusual and would certainly I think complicate diagnostics. If you had a scanner and it worked then it would certainly create diagnostic issues.

Clean and check connector to the VSS first - remove VSS and spin with rotary device. Get your self a seal GM# 15552872 so you can reseal the VSS when going back together if you remove it. It should be on all dealers shelves.

[herc795]

Thanks, Yes I still have the Delco Bose and the SCV is also not working now. Nice to know that the VSS for a 91 will work because it is very difficult to find. I will take the VSS out and check the connector.
Thanks for the info

DT

[edram454]

It definitely sounds like the vss. It is not just hard to get, it is impossible to get unless you know somebody who has a new one in the box. Nobody has a 1990 vss for sale in any business. I did sell a new one in a box when I sold my z to a forum member but I cannot disclose his name unfortunately. I believe you can modify a 1991 to make it work for your 90. Good Luck.

edram454

[edram454]

btw, the more you drive it the worse it will drive because the computer will think the car is not moving and it will get choppier and slower and on and on until it will run like total crap so dont drive it too much. that is the experience I had with mine. I think I bought the last two available in some old dirty parts bin from GSI Engine Management Group. They acutally made them for GM and by some miracle they found two deep in a old parts bin. They charged me so much for it they did not even put a price on the receipt. I paid around $300 a piece and I bought both. I used one and had a spare. It was item 31018 VEH speed sensor. This was on 3/26/2014. Whats it worth now?? a lot more I guess.

edram454

[herc795]

I am going to get a 91 VSS.

Thanks

[herc795]

Well I took the VSS out and there is no drive gear (77) on the main transmission shaft. What is the gear made of and any suggestion what could of happen to it. There was one sliver of plastic and that was it.

[WVZR-1]

Well I took the VSS out and there is no drive gear (77) on the main transmission shaft. What is the gear made of and any suggestion what could of happen to it. There was one sliver of plastic and that was it.

If the retainer(76) failed anything is possible. If the retainer (76) is still there and holding just the remnants of what was the drive gear then I'd think the VSS froze and the driven took out the drive BUT I'd doubt that. I don't know that I've ever seen the drive fail unless the retainer broke. Did you check the VSS and the driven gear? Is the driven gear OK or does it display some damage also? Did the speedometer ever work for you? Could you spin the driven gear on the VSS? Did you try the VSS with a rotary tool?

[herc795]

Once I got the VSS out I hooked back up turn ignition switch on and put drill on the end of VSS and the speedometer worked. there is no remnants of drive gear. If the retainer failed would the drive gear move forward?

[herc795]

The other question is what is the gear made of?

[Marc Haibeck]

The gear can't go farther forward than the sensor mount. It's now located on the output shaft somewhere between the sensor and the drive shaft slip yolk. If the drive shaft is removed the gear can be removed from the output shaft.

The OE gear has 13 teeth and is grey plastic material. It is retained with a spring clip. In the late '90's there was an aftermarket metal 14 tooth gear that was pressed on. It was used for speedometer correction with a 3.90 axle gear set. Sometimes it was incorrectly used for other ratios.

[Marc Haibeck]

Correction. The OE gear has 15 teeth.

[herc795]

Marc,
The other question I have is what caused this to happen? In order to fix it will I need to drop the transmission? Where can I get the correct parts?

[WVZR-1]

Marc,
The other question I have is what caused this to happen? In order to fix it will I need to drop the transmission? Where can I get the correct parts?

How long have you owned this car? Does it still have the factory rear axle ratio? Speedo quit when?

The gear if it's a factory ratio and the 15 tooth is needed nearly anyone whose done a gear change and did a mechanical correction that requires a different drive should have their OE to sell!! The retainer is a different issue.

Perhaps since Marc has responded to this thread maybe he'll revisit and mention what your next "to do" should be. Is the VSS still removed and car on a lift or back together?

*** sorry I didn't see the post was directed to Marc

[herc795]

WVZR-1,
It stopped working when I was driving this fall, in fact it was the last time before I put the car away. I still have it apart, need to fix it. I have the car since 2005. I believe it has stock rear end.

[Marc Haibeck]

If the clip fell off, it's probably in the tail extension. Search for it with a magnet.

The gear should be on the shaft a few inches to the rear of the sensor hole. maybe you can fish it back forward with an 8" wire with a hook.

[herc795]

I dropped the transmission and took the rear extension housing off. I believe the drive gear clip failed. this caused the teeth on the drive gear to get chewed up some. I need to find a new drive gear and clip, anyone have an idea where I could find them.