91 speedometer question
Thread Starter
Joined: Mar 2002
Posts: 854
Likes: 10
From: Rincon, Ga.
Car: 91 Camaro RS
Engine: 305 TPI conversion.
Transmission: T56
Axle/Gears: 3.73 posi 4th gen rear
91 speedometer question
i havet a 5 speed tbi converted to a 92 tpi. after a while the speedo stopped and the car felt like it was in limp mode. i disconnected the battery and reset it and the engine runs fine with no codes.
i switched out the speed sensor with another and nothing. i read somewhere that tpi cars do not use the yellow buffer box. so i should not even have it plugged in.
ive read some threads on speedometer fixes, and want to know where i should start.
i switched out the speed sensor with another and nothing. i read somewhere that tpi cars do not use the yellow buffer box. so i should not even have it plugged in.
ive read some threads on speedometer fixes, and want to know where i should start.
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Joined: Jan 2006
Posts: 3,341
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From: Mooresville NC
Car: LOWERED ♦ CRIMSON METALFLAKE
Engine: ► 400 KUBES ◄
Transmission: 765R4
Axle/Gears: EATON POSI 4.56
A Speedo Is Good For The Summer
Gain access to the buffer which looks like this:
It’s located behind the instrument panel at the right.
Connect an audio amplifier to terminal A yellow wire to make sure it’s getting a steady signal.
Ground to ground, the signal wire to terminal A yellow wire of the VSS.
With the car on jackstands listed for a hum from the amplifier when the rear wheels are rotating.
If you do, then find out if you get a hum from terminal C tan wire.
The tan wire then goes to the speedometer unit.
If it gets to the speedometer but the speedometer does not work, have it repaired or replace the unit.
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8 Wheels Corner Better Than 4, If You’re On The Outside You Have Fair Warning
It’s located behind the instrument panel at the right.
Connect an audio amplifier to terminal A yellow wire to make sure it’s getting a steady signal.
Ground to ground, the signal wire to terminal A yellow wire of the VSS.
With the car on jackstands listed for a hum from the amplifier when the rear wheels are rotating.
If you do, then find out if you get a hum from terminal C tan wire.
The tan wire then goes to the speedometer unit.
If it gets to the speedometer but the speedometer does not work, have it repaired or replace the unit.
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
Happy Racing !
◙◙◙◙◙◙◙◙◙◙◙◙◙◙◙
8 Wheels Corner Better Than 4, If You’re On The Outside You Have Fair Warning
Thread Starter
Joined: Mar 2002
Posts: 854
Likes: 10
From: Rincon, Ga.
Car: 91 Camaro RS
Engine: 305 TPI conversion.
Transmission: T56
Axle/Gears: 3.73 posi 4th gen rear
Re: 91 speedometer question
in another thread it was posted that the buffet box is not used on 91-92 tpi engines. can anyone confirm this?
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Joined: Sep 2006
Posts: 340
Likes: 1
From: Fort Hood, Texas
Car: 1991 Camaro Z28
Engine: 2002 SS LS1
Transmission: 6 speed
Axle/Gears: Auburn 3.42
Junior Member
iTrader: (2)
Joined: Jul 2013
Posts: 94
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From: pennsylvania
Car: 85 iroc z, 03 ram 1500
Engine: 305 tpi, 287
Transmission: WC T5, NV3500
Axle/Gears: 3.42, 3.55s
Re: 91 speedometer question
I had the same problem with my iroc. if you look at my thread( speedometer and odometer) Camaro tucker ends up telling me how to repin the harness for the tpi system
Thread Starter
Joined: Mar 2002
Posts: 854
Likes: 10
From: Rincon, Ga.
Car: 91 Camaro RS
Engine: 305 TPI conversion.
Transmission: T56
Axle/Gears: 3.73 posi 4th gen rear
Re: 91 speedometer question
I read it. ill try it this weekend and post results
thanks
thanks
Joined: Jun 2009
Posts: 832
Likes: 1
From: Lawrence KS
Car: 91 z28
Engine: LS1
Transmission: 4L60e
Axle/Gears: 10 bolt 3.42
Re: 91 speedometer question
The VSS is being sent to a dead end at C207. TPI interior harness routes the signal differently than TBI.
TPI sends VSS as a 4,000 signal via the PCM (no buffer box), while the TBI/V6 sends VSS/cruise from PCM as a 2,000 signal which gets converted to 4,000 via the buffer box.
91 TBI converted to 92 TPI, (92 TPI engine harness and computer) (91 TBI interior harness)
speedo, Pin D "GRY" of C207 (clear side) must move to pin k "BRN" (clear side).
cruise, pin E (buffer box) must connect to C207 pin P "red" (black side) (may have to run your own wire for this)
Connect pin F to pin C (buffer box) box can now be removed if desired.
TPI sends VSS as a 4,000 signal via the PCM (no buffer box), while the TBI/V6 sends VSS/cruise from PCM as a 2,000 signal which gets converted to 4,000 via the buffer box.
91 TBI converted to 92 TPI, (92 TPI engine harness and computer) (91 TBI interior harness)
speedo, Pin D "GRY" of C207 (clear side) must move to pin k "BRN" (clear side).
cruise, pin E (buffer box) must connect to C207 pin P "red" (black side) (may have to run your own wire for this)
Connect pin F to pin C (buffer box) box can now be removed if desired.
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Joined: Jun 2009
Posts: 832
Likes: 1
From: Lawrence KS
Car: 91 z28
Engine: LS1
Transmission: 4L60e
Axle/Gears: 10 bolt 3.42
Re: 91 speedometer question
Specifically no, you have to sort through schematics.
c207 post #1
https://www.thirdgen.org/forums/ltx-...formation.html
vss/buffer box post #9
https://www.thirdgen.org/forums/elec...-odometer.html
c207 post #1
https://www.thirdgen.org/forums/ltx-...formation.html
vss/buffer box post #9
https://www.thirdgen.org/forums/elec...-odometer.html
Last edited by camarotucker; Oct 19, 2014 at 05:59 PM. Reason: add links
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Joined: Aug 2005
Posts: 326
Likes: 1
From: edmonton alberta canada
Car: 91 rs,1 92 rs,92 b4c/1le
Engine: 5.0tbi,5.7 tune port/5.0tpi
Transmission: 5spdx2 and t56
Axle/Gears: 3.08,3.73,3.42
Re: 91 speedometer question
when I swapped mine I just moved the brown wire at the white plastic connector to the other side there was a thread about it very easy worked fine
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