vehicle speed sensor manual
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2nd Gear
Joined: Oct 2013
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vehicle speed sensor manual
Hey, i have a 89 corvette with a manual transmission (zf6). From searching and reading the forums i believe my vss needs to be replaced. i got error code 24 and my speedometer does not work. Anyways, i have no idea where to find one. It appears they have discontinued it. I think its model number is sc6. Anyone have any idea of someone who may still carry it? I have searched google, called a local corvette parts place, checked ebay and the salvage yards.
Team Owner
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I would remove the VSS and inspect the condition of the gears first and then spin the VSS with a drill or rotary tool to confirm that it is "in fact" not producing the proper signal. If you need one they are difficult to find and somewhat expensive.
Pickup a 15552872 GM seal to use when you reinstall.
Pickup a 15552872 GM seal to use when you reinstall.
Team Owner
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Spin the VSS with a drill or other rotary tool and with a DVM check for AC volts output using lowest AC voltage available on the DVM. Your looking for something very low voltage less than 5V AC maybe 2.5V AC depending on how fast it's rotated. A 1/2 or 3/8 drill will do well.
The VSS can leak from the electrical connector but that should be minimal. Clean and reconnect if the VSS output registers. If you've no AC signal from the spinning of the VSS I believe it could be assumed you need one. You could just keep an eye on the connector for seepage and react if it gets really bad. I've seen people use a sealant at the connector an accomplish a satisfactory fix for a minimal leak.
The VSS can leak from the electrical connector but that should be minimal. Clean and reconnect if the VSS output registers. If you've no AC signal from the spinning of the VSS I believe it could be assumed you need one. You could just keep an eye on the connector for seepage and react if it gets really bad. I've seen people use a sealant at the connector an accomplish a satisfactory fix for a minimal leak.
Last edited by WVZR-1; Oct 3, 2013 at 05:03 PM.
Team Owner
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His VSS is the same as used from '85 production through '90 - there's much misinformation out there from many! I've got VSS's that are correct and they do AC.
Last edited by WVZR-1; Oct 3, 2013 at 06:07 PM.
Drifting
Joined: May 2013
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From: Reno Nevada
engines thru 1992, all computer-controlled-carbureted engines, and on 1985-1989 TPI engines.
2. A four-pulse (4000 pulses per mile) sine-wave (A.C. current or alternating current) signal is
required by the 1990-1993 TPI, 1992-1993 LT1 engines, and 1990-1993 Camaro 3.1/3.4 V6
engines.
3. A 40 pulse per driveshaft revolution speed sensor used on 1993 and newer trucks with automatic
transmission, 1994 and newer rear drive cars with the automatic transmission
4. A 17 tooth per driveshaft revolution speed sensor used on 1993-1997 LT1 engines with the Borg-
Warner 6-speed transmission. An 11 tooth reluctor ring is used on 1993 LT1 engines with the
Borg-Warner wide ratio (3.35 First gear) 6-speed transmission.
http://www.jagsthatrun.com/V8-chapte...ed-Sensors.pdf
Team Owner
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1. The two-pulse (2000 pulses per mile) square wave (D.C current or direct current) used on all TBI
engines thru 1992, all computer-controlled-carbureted engines, and on 1985-1989 TPI engines.
2. A four-pulse (4000 pulses per mile) sine-wave (A.C. current or alternating current) signal is
required by the 1990-1993 TPI, 1992-1993 LT1 engines, and 1990-1993 Camaro 3.1/3.4 V6
engines.
3. A 40 pulse per driveshaft revolution speed sensor used on 1993 and newer trucks with automatic
transmission, 1994 and newer rear drive cars with the automatic transmission
4. A 17 tooth per driveshaft revolution speed sensor used on 1993-1997 LT1 engines with the Borg-
Warner 6-speed transmission. An 11 tooth reluctor ring is used on 1993 LT1 engines with the
Borg-Warner wide ratio (3.35 First gear) 6-speed transmission.
http://www.jagsthatrun.com/V8-chapte...ed-Sensors.pdf
engines thru 1992, all computer-controlled-carbureted engines, and on 1985-1989 TPI engines.
2. A four-pulse (4000 pulses per mile) sine-wave (A.C. current or alternating current) signal is
required by the 1990-1993 TPI, 1992-1993 LT1 engines, and 1990-1993 Camaro 3.1/3.4 V6
engines.
3. A 40 pulse per driveshaft revolution speed sensor used on 1993 and newer trucks with automatic
transmission, 1994 and newer rear drive cars with the automatic transmission
4. A 17 tooth per driveshaft revolution speed sensor used on 1993-1997 LT1 engines with the Borg-
Warner 6-speed transmission. An 11 tooth reluctor ring is used on 1993 LT1 engines with the
Borg-Warner wide ratio (3.35 First gear) 6-speed transmission.
http://www.jagsthatrun.com/V8-chapte...ed-Sensors.pdf
The components in the vehicle (ECM, CCM, IP whichever changes the sine wave AC to the square wave signal that it wants to see for the conversion to 2000 pulse. That's the best layman description I've ever been able to manage for myself.
Last edited by WVZR-1; Oct 3, 2013 at 06:23 PM.
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Drifting
Joined: May 2013
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From: Reno Nevada
Buy a VSS and try it - I said there's much misinformation out there and you just "verified it"
The components in the vehicle (ECM, CCM, IP whichever changes the sine wave AC to the square wave signal that it wants to see for the conversion to 2000 pulse. That's the best layman description I've ever been able to manage for myself.
The components in the vehicle (ECM, CCM, IP whichever changes the sine wave AC to the square wave signal that it wants to see for the conversion to 2000 pulse. That's the best layman description I've ever been able to manage for myself.
Team Owner
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Is all of what I just mentioned "gospel" - likely NOT!
Drifting
Joined: May 2013
Posts: 1,736
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From: Reno Nevada
I couldn't remark directly to that but in the early digital cluster I believe the speedometer was the "first stop" for the VSS signal and it was distributed from there. In '90 the VSS signal went to the CCM and was distributed from there to where ever. There weren't any DRACS or buffers for the Corvette, buffers for the Camaro/Firebird and DRACs and DRABs for the TBI trucks and such. DRACs/DRABs were one time write pieces used for ratio/tire combinations and buffers were just a converter from the AC analog (I believe that's correct) to the DC required by the other components ECM/PCM/ABS etc. I believe on some applications there were combinations of different PPM's for speed, ECM/PCM and yet a third for the ABS. I just dealt with each application separately and had to sort the misinformation that was out there.
Is all of what I just mentioned "gospel" - likely NOT!
Is all of what I just mentioned "gospel" - likely NOT!
http://www.chevythunder.com/fuel%20i...ts.htm#1990-91 speed density (Corvette ecm #1227727)
Thank you for broadening my awareness!
To the OP:
Sorry for the highjack. There's 2 options for your year, and I've heard the one that's more readily available will work if turned 180 degrees. I'm sure other can expounds more on this.
http://www.corvetteforum.net/c4/vett...Gearshtm.shtml
Last edited by MrWillys; Oct 3, 2013 at 07:57 PM.
Race Director
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From: Anaheim CA
1989 uses two different VSS senders, depending on the rear axle ratio. Check this chart:
It is my understanding that the VSS shaft for the lower ratio gears is centered and the one for the higher ratio gears is offset to allow room for a larger driven gear. Given that, I don't see how you could "turn it over" to make it work.
In 1984 - 1989 the VSS signal goes to the dashboard first and then to the ECM. I believe it's a square wave as it comes out of the VSS. I'm several hundreds of miles from home so I can't do a test. It would be easy to look at for me because I have the original 700r4 out of my car in the garage.
It is my understanding that the VSS shaft for the lower ratio gears is centered and the one for the higher ratio gears is offset to allow room for a larger driven gear. Given that, I don't see how you could "turn it over" to make it work.
In 1984 - 1989 the VSS signal goes to the dashboard first and then to the ECM. I believe it's a square wave as it comes out of the VSS. I'm several hundreds of miles from home so I can't do a test. It would be easy to look at for me because I have the original 700r4 out of my car in the garage.
Drifting
Joined: May 2013
Posts: 1,736
Likes: 31
From: Reno Nevada
In 1984 - 1989 the VSS signal goes to the dashboard first and then to the ECM. I believe it's a square wave as it comes out of the VSS. I'm several hundreds of miles from home so I can't do a test. It would be easy to look at for me because I have the original 700r4 out of my car in the garage.
I agree with you that the 84 to 89 goes to the dash first but disagree the output is a square wave. If you look at the link I posted you will note the same VSS was used through the 1990 model year. This tells me it's converted at the dash. Also, when I look at the Camaro it sends a 4 PPM signal to the speedo, but a 2 PPM signal to the cruise control.
When you get home and test it if the value is a square wave please post up!
Team Owner
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Regardless it's an AC voltage that you could have mentioned and confirmed!