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'91 T5 speed sensor

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Old Apr 20, 2023 | 04:47 PM
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'91 T5 speed sensor

Curious if anyone might be able to identify this speed sensor on my '91 T5. The plug style is different than the harness connector, but hoping that maybe it's the right wave and pulse and I can just adapt to it.


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Old Apr 20, 2023 | 06:25 PM
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From: SW Missouri
Car: 1989 Trans Am
Engine: sp357
Transmission: TKX
Re: '91 T5 speed sensor

What are you trying to adapt it to? Appears to be the correct speed sensor that came on the cars that didn't have cable speedometers.
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Old Apr 21, 2023 | 08:06 PM
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Re: '91 T5 speed sensor

I say "adapt" because the connector style is different thany connector, so I wasn't sure if there was a difference for certain years, or if this was for a different T5 application.


This sensor is a barrel style plug where the pigtail on the car is the style in the other attached photo



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Old Apr 21, 2023 | 08:06 PM
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Re: '91 T5 speed sensor

For reference too, just running stock TBI setup
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Old Apr 21, 2023 | 08:27 PM
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From: SW Missouri
Car: 1989 Trans Am
Engine: sp357
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Re: '91 T5 speed sensor

Weird. My '89 TBI has the correct connector, it was the same for all model years that had the electronic sending unit in the transmission as far as I am aware.

Shouldn't be a problem to just adapt it with a couple of plugs, it doesn't even matter which wire is which as it's a AC signal.
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Old Apr 22, 2023 | 12:17 PM
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Axle/Gears: 4.11 LS1 Rear End
Re: '91 T5 speed sensor

danderson: The speedo sending unit in your pics is from 84-89 Thirdgens. There is also a second style that was used in the 90-92 cars. Both of those types of T5 electric Speedo Sending units are very hard to locate these days.

It sure looks like simply changing the plug will work for you. I have never done it,.. but the 88 and the 91 shop manual both describe a 4000 PPM sensor,... So I assume that swapping to the correct plug is all you'll need to do.

P.S. Be sure to verify that both your plastic Speedo gears are correct while your in there !!


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Old Apr 22, 2023 | 12:30 PM
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From: SW Missouri
Car: 1989 Trans Am
Engine: sp357
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Re: '91 T5 speed sensor

Originally Posted by John in RI
danderson: The speedo sending unit in your pics is from 84-89 Thirdgens. There is also a second style that was used in the 90-92 cars. Both of those types of T5 electric Speedo Sending units are very hard to locate these days.

It sure looks like simply changing the plug will work for you. I have never done it,.. but the 88 and the 91 shop manual both describe a 4000 PPM sensor,... So I assume that swapping to the correct plug is all you'll need to do.

P.S. Be sure to verify that both your plastic Speedo gears are correct while your in there !!

Looks like John is on the money as usual. Found this pic of the '90+ sensor courtesy of member 1froggy1 and sure enough has the different plug.


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Old Apr 22, 2023 | 01:17 PM
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Re: '91 T5 speed sensor

Originally Posted by John in RI
danderson: The speedo sending unit in your pics is from 84-89 Thirdgens. There is also a second style that was used in the 90-92 cars. Both of those types of T5 electric Speedo Sending units are very hard to locate these days.

It sure looks like simply changing the plug will work for you. I have never done it,.. but the 88 and the 91 shop manual both describe a 4000 PPM sensor,... So I assume that swapping to the correct plug is all you'll need to do.

P.S. Be sure to verify that both your plastic Speedo gears are correct while your in there !!

That makes a lot more sense, thanks John! And confirming the 4k PPM for both us also reassuring. I found a harness from Michigan Motorsports to use the 90-92 sensor with the 84-89 harness, too bad it's not the other way around.. lol. But simple enough to find a female pigtail for the newer H11 style connector and the older male weather pack

https://www.michiganmotorsports.com/...89-tbi-tpi-gm/
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Old Apr 23, 2023 | 04:26 PM
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Transmission: Tremec T-56
Axle/Gears: 12 Bolt 3.73
Re: '91 T5 speed sensor

I hope that works for you, but my from recollection that sensor is a 2000 pulse.
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Old Apr 23, 2023 | 05:35 PM
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Re: '91 T5 speed sensor

I wasn't 100% positive,..... so I checked before posting.

84-89 style VSS:
From the 85 Camaro/Berlinetta Shop manual:


From the 86 Firebird Shop manual:


From the 88 Firebird Shop manual:


90-92 style VSS:
From the 91 Camaro Shop manual:



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Old Apr 24, 2023 | 09:42 AM
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Engine: 355 w/AFR 195's Elem. 400/430 HP/TQ
Transmission: Tremec T-56
Axle/Gears: 12 Bolt 3.73
Re: '91 T5 speed sensor

Good info, I knew it put out 2000 somewhere.
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Old May 25, 2023 | 08:15 PM
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Re: '91 T5 speed sensor

To follow up on this, now that I've had it out driving - sensor works perfect and speedometer is about spot-on. Thanks again guys for the help!
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