1990 Corvette Speedo
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1990 Corvette Speedo
Hi,
Just got my 1990 Back from the shop and noticed the speedo is not registering unless I'm going fast. It stays at 0 at town speeds. Could they have knocked something fitting the new injectors.
Just got my 1990 Back from the shop and noticed the speedo is not registering unless I'm going fast. It stays at 0 at town speeds. Could they have knocked something fitting the new injectors.
Last edited by Tony Trans Am; Nov 25, 2014 at 02:49 PM.
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From: Anaheim CA
If you have a C68 HVAC system you can check your speed on the HVAC controller. There's a video on YouTube on how to do this:
The vehicle speed goes from the VSS in the trans to the PCM and then to the dash. You want to determine if it's getting lost before or after the PCM. That will narrow things down and make it easier to find the problem.
The vehicle speed goes from the VSS in the trans to the PCM and then to the dash. You want to determine if it's getting lost before or after the PCM. That will narrow things down and make it easier to find the problem.
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I'd think it more coincidental than anything that they created. First of all if the speedometer LCD works the speed of the car should have NO effect. I'd first check the VSS electrical connector at the transmission. It isn't unusual for that connector/connection to get flaky. On a '90 it's a very straight forward weather-pack shell that you can buy service terminals at most every auto parts store or fleet vehicle dealer. I'd do nothing else first.
A bad VSS? Maybe. Do you have a FSM? At the ECM the VSS is pinned to G2 (yellow) and G8 (purple). You maybe want to be concerned with the "purple" at the VSS and ECM. I assumed your car is an L98 and NOT a ZR-1/LT5.
Does your cruise control work at both high and low speeds?
A bad VSS? Maybe. Do you have a FSM? At the ECM the VSS is pinned to G2 (yellow) and G8 (purple). You maybe want to be concerned with the "purple" at the VSS and ECM. I assumed your car is an L98 and NOT a ZR-1/LT5.
Does your cruise control work at both high and low speeds?
Last edited by WVZR-1; Nov 26, 2014 at 06:30 PM.
Melting Slicks
Joined: Sep 2008
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From: Cherokee National Forest TN
My 90 decided to stick @ 46mph. I have a short fuse sooooo a few smacks on the top of the dash with a closed fist brought it back to life. The next time the cluster was removed I cleaned the printed circuit & plug in connector = no more issues.
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Does the VSS effect the overdrive unit.
Driving my 90 vette around today and the speedo started to work perfectly until I got back to London, It of felt as if the over drive couldn't make it's mind up whether it was in or out. What RPM should it turning at 70mph.
Thread Starter
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I'd think it more coincidental than anything that they created. First of all if the speedometer LCD works the speed of the car should have NO effect. I'd first check the VSS electrical connector at the transmission. It isn't unusual for that connector/connection to get flaky. On a '90 it's a very straight forward weather-pack shell that you can buy service terminals at most every auto parts store or fleet vehicle dealer. I'd do nothing else first.
A bad VSS? Maybe. Do you have a FSM? At the ECM the VSS is pinned to G2 (yellow) and G8 (purple). You maybe want to be concerned with the "purple" at the VSS and ECM. I assumed your car is an L98 and NOT a ZR-1/LT5.
Does your cruise control work at both high and low speeds?
A bad VSS? Maybe. Do you have a FSM? At the ECM the VSS is pinned to G2 (yellow) and G8 (purple). You maybe want to be concerned with the "purple" at the VSS and ECM. I assumed your car is an L98 and NOT a ZR-1/LT5.
Does your cruise control work at both high and low speeds?
What's a FSM? What's an ECM? I am from the U.K.
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Driving my L98 90 vette around today and the speedo started to work perfectly until I got back to London, It felt as if the over drive couldn't make it's mind up whether it was in or out. What RPM should it turning at 70mph. In regards to speedo how can it work perfectly then not, surely it's the speed sensor as the dash would either work or not work.
What's a FSM? What's an ECM? I am from the U.K.
What's a FSM? What's an ECM? I am from the U.K.
ECM - Engine Control Module (black box up near the booster)
G2 and G8 are the pins at the ECM where the VSS wires connect. Check the wires yellow and purple at the VSS connector, confirm connection and move on. You hadn't mentioned UK before so sourcing your needs could be interesting. There are a couple very good resellers there though. Put your location in your profile and maybe another UK guy will respond.
Last edited by WVZR-1; Nov 30, 2014 at 03:33 PM.
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FSM - Factory Service Manual
ECM - Engine Control Module (black box up near the booster)
G2 and G8 are the pins at the ECM where the VSS wires connect. Check the wires yellow and purple at the VSS connector, confirm connection and move on. You hadn't mentioned UK before so sourcing your needs could be interesting. There are a couple very good resellers there though. Put your location in your profile and maybe another UK guy will respond.
ECM - Engine Control Module (black box up near the booster)
G2 and G8 are the pins at the ECM where the VSS wires connect. Check the wires yellow and purple at the VSS connector, confirm connection and move on. You hadn't mentioned UK before so sourcing your needs could be interesting. There are a couple very good resellers there though. Put your location in your profile and maybe another UK guy will respond.
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Here's an ECM pin-out chart for L98, page down to '90 & '91:
http://chevythunder.com/fuel%20injec...ts.htm#1990-91 speed density (Corvette ecm #1227727)
In this one page down to L98 '90 & '91:
https://wiki.bentleypublishers.com/p...ageId=17989640
The VSS is drivers side rear of the transmission. On a '90 it's either black or white in color 2 1/2" in diameter with the yellow/purple connector in the center.
Last edited by WVZR-1; Nov 30, 2014 at 06:53 PM.
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1990 l98 vss
Does anyone have a definitive picture of the VSS.
Whilst trying to remove mine today it all fell apart springs the lot! I'm not sure if there is a piece still in the transmission. How is it fitted in there, twists etc. I tried levering it out hence it went ping!
Where can I get a new one?
super pissed off!
Whilst trying to remove mine today it all fell apart springs the lot! I'm not sure if there is a piece still in the transmission. How is it fitted in there, twists etc. I tried levering it out hence it went ping!
Where can I get a new one?
super pissed off!
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Do you have a pic of yours pulled?
How do you pull it out?
Last edited by Tony Trans Am; Dec 6, 2014 at 10:24 AM.
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There will of course be some "incorrect" images BUT I can assure you that the image I borrowed is correct and you should recognize it as what you demolished. You apparently tried prying on the sleeve that is used as a retainer around the circumference of the VSS. You need to pull straight out and you can wiggle/twist some to help.
Last edited by WVZR-1; Dec 6, 2014 at 10:50 AM.
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Just "GOOGLE" 25007308 and you'll find many different images. If you've demolished the VSS retaining ring and the black center aspect then you need and the black is quite expensive. Not available as new any longer and used gets expensive also. I might have a black/correct NOS but it would be expensive.
There will of course be some "incorrect" images BUT I can assure you that the image I borrowed is correct and you should recognize it as what you demolished. You apparently tried prying on the sleeve that is used as a retainer around the circumference of the VSS. You need to pull straight out and you can wiggle/twist some to help.
There will of course be some "incorrect" images BUT I can assure you that the image I borrowed is correct and you should recognize it as what you demolished. You apparently tried prying on the sleeve that is used as a retainer around the circumference of the VSS. You need to pull straight out and you can wiggle/twist some to help.
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Your 2 tooth count and the black VSS indicates that your '90 should be a 3.07 rear axle ratio. G44 on the SPID label that should be attached to the back-side of the console door.
I've received your emails and I'll be back to you.