VSS Questions
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Supreme Member
Joined: Dec 2003
Posts: 2,391
Likes: 1
From: Newark, DE
Car: '86 Camaro, '02 WRX, '87 K5, '67
Engine: 350 TPI, 2.0turbo, 383 in the works, 289-4BBL, 232, A-head 4-cylinder
Transmission: T56, 5-speed, 700R4, C4, T176, semi-auto 2-speed
Axle/Gears: 3.73, 3.90, 4.88, 3.55, 3.54, 7.00
VSS Questions
An electrical question was raised on the trans/drivetrain forum. I haven't been able to get a definitive answer, so I'm hoping that someone here will have some answers.
I have an '86 IROC Z28. It had a 700R4 stock, but I replaced it with a T56. The car had a mechanical speedo from the factory, so I just ditched the factory gauges and built a new dash with Autometer gauges, including the electronic speedo.
I'm running the speedo directly off the VSS in the T56, and have no VSS related trouble codes. I've been told that the factory speedo, though mechanical, incorporated a VSS that sent a signal to the ECM. I can find no proof of this in any of my wiring diagrams, but I know they aren't totally accurate (Haynes manual). Is this true? If so how do I know which wire to intercept? My speedo has a VSS output for this purpose, but I would need to know which wire or ECM pin is the right one, if this is even true?
I have an '86 IROC Z28. It had a 700R4 stock, but I replaced it with a T56. The car had a mechanical speedo from the factory, so I just ditched the factory gauges and built a new dash with Autometer gauges, including the electronic speedo.
I'm running the speedo directly off the VSS in the T56, and have no VSS related trouble codes. I've been told that the factory speedo, though mechanical, incorporated a VSS that sent a signal to the ECM. I can find no proof of this in any of my wiring diagrams, but I know they aren't totally accurate (Haynes manual). Is this true? If so how do I know which wire to intercept? My speedo has a VSS output for this purpose, but I would need to know which wire or ECM pin is the right one, if this is even true?
Supreme Member
Joined: Jun 2001
Posts: 9,550
Likes: 5
From: Charleston, SC
Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
yes its true, even my crossfire 82 had a VSS... its behind/built into the gauge cluster... most of the time, they're bright yellow.
if you can find it on your old gauge cluster, you should be able to trace the path to the connector by eye on the film circuit... then go from there..
if you can find it on your old gauge cluster, you should be able to trace the path to the connector by eye on the film circuit... then go from there..
Thread Starter
Supreme Member
Joined: Dec 2003
Posts: 2,391
Likes: 1
From: Newark, DE
Car: '86 Camaro, '02 WRX, '87 K5, '67
Engine: 350 TPI, 2.0turbo, 383 in the works, 289-4BBL, 232, A-head 4-cylinder
Transmission: T56, 5-speed, 700R4, C4, T176, semi-auto 2-speed
Axle/Gears: 3.73, 3.90, 4.88, 3.55, 3.54, 7.00
Crap, I knew I souldn't have sold it...
I'll try to check one out in a junkyard once the weather clears.
Thanks.
I'll try to check one out in a junkyard once the weather clears.
Thanks.
Thread Starter
Supreme Member
Joined: Dec 2003
Posts: 2,391
Likes: 1
From: Newark, DE
Car: '86 Camaro, '02 WRX, '87 K5, '67
Engine: 350 TPI, 2.0turbo, 383 in the works, 289-4BBL, 232, A-head 4-cylinder
Transmission: T56, 5-speed, 700R4, C4, T176, semi-auto 2-speed
Axle/Gears: 3.73, 3.90, 4.88, 3.55, 3.54, 7.00
I wonder why I'm not getting a VSS code though.
I am running a TPIS chip that was burned specifically for the T56 swap and a few other things I've done to the car. I wonder if they programmed around the VSS, knowing that it would be a problem.
I am running a TPIS chip that was burned specifically for the T56 swap and a few other things I've done to the car. I wonder if they programmed around the VSS, knowing that it would be a problem.
Supreme Member
Joined: Jun 2001
Posts: 9,550
Likes: 5
From: Charleston, SC
Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
Originally posted by TKOPerformance
I wonder why I'm not getting a VSS code though.
I am running a TPIS chip that was burned specifically for the T56 swap and a few other things I've done to the car. I wonder if they programmed around the VSS, knowing that it would be a problem.
I wonder why I'm not getting a VSS code though.
I am running a TPIS chip that was burned specifically for the T56 swap and a few other things I've done to the car. I wonder if they programmed around the VSS, knowing that it would be a problem.
my 91 TBI ran fine with a broken VSS connector for a full month... no speedo, no signal to ECM..
i donno why, but i never got a code.... i later put a new VSS in, and it worked fine... (keep in mind the 90-92s had the VSS in the tailshaft)
Thread Starter
Supreme Member
Joined: Dec 2003
Posts: 2,391
Likes: 1
From: Newark, DE
Car: '86 Camaro, '02 WRX, '87 K5, '67
Engine: 350 TPI, 2.0turbo, 383 in the works, 289-4BBL, 232, A-head 4-cylinder
Transmission: T56, 5-speed, 700R4, C4, T176, semi-auto 2-speed
Axle/Gears: 3.73, 3.90, 4.88, 3.55, 3.54, 7.00
The computer must not need a set value coming from the sensor like it does with say a knock sensor.
I'll research it a little more and probably see what's involved in reconnecting it at some point in the future. I may have to run a buffer box between the speedo and the ECM (4th gen VSS is a different waveform than the 3rd gen).
I'll research it a little more and probably see what's involved in reconnecting it at some point in the future. I may have to run a buffer box between the speedo and the ECM (4th gen VSS is a different waveform than the 3rd gen).
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