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Speedometer Not Working Rate Topic: -----

#1 User is offline   TimboBiotchie 

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  • Engine: v6 3.4L
  • Transmission: Manual 5-Speed

Posted 21 July 2012 - 10:50 AM

Okay here's my situation:

I have a 95 firebird v6, 3.4l, manual. It has a 97 trans-am transmission in it. I went to the store and bought a new speed-sensor clip to hook up the speedometer. (It plugged into a socket underneath the car, around the front middle). When I backed out of my driveway, the speedometer would float up to like 30-40 mph. I tried taking it down the road, and as I shifted into 2nd gear, my speedometer maxed out at 110 and shut my car off. After that, we tried unhooking the battery to try and reset the computer before plugging the speed sensor back in, but came out with the same results.

So for now, I still have it unplugged, so I can drive my car, and just use my GPS to see how fast I'm going. But also with the speedometer not hooked up, the odometer isn't working, so there's no true way to say how many miles are on the car, it's sitting at 137k right now.

So my question is: Has anyone run into this problem before, and is there anything I can do to fix it? Some of my mechanic friends say it may be the sensors are wrong, one mechanic told me there was nothing I could do, and just buy an after-market speedometer.

Any thoughts/suggestions are greatly appreciated.

-Tim-
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#2 User is offline   Injuneer 

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Posted 21 July 2012 - 12:09 PM

Is your 97 trans a 4L60E automatic? I suspect the problem is the 4L60E VSS puts out 40 pulses per drivesahft revolution, and your manual trans (T5) was probably similar to the T56 used in the V8 cars, with a VSS that puts out 17 pulses per driveshaft revolution. That would make the PCM interpret the vehicle speed as 2.35 X actual speed, so the PCM would trip the 110MPH top speed limiter at a true 47 MPH.

If you have an automatic, the PCM needs to be reflashed with an automatic program.

If you managed to put a manual T56 into it, that isn't the problem.
1994 FIREBIRD FORMULA

FRED

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381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

NO PHOTOS - MY WEBSITE IS BEING MOVED TO ANOTHER SERVER - SORRY FOR ANY INCONVENIENCE
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#3 User is offline   TimboBiotchie 

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  • Transmission: Manual 5-Speed

Posted 21 July 2012 - 01:07 PM

Ah gotcha, that makes sense. I'm not 100% sure, but I believe the guy I bought the car from said it was a transmission from a 97 trans-am. I'm going to try and get a hold of him and check exactly what the transmission is from so we can better diagnose this problem.

Thanks for the input, and I'll repost once I know for sure what the transmission is from.

-Tim-
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#4 User is offline   Injuneer 

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Posted 21 July 2012 - 08:53 PM

Is the 97 transmission a manual or an automatic?
1994 FIREBIRD FORMULA

FRED

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381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

NO PHOTOS - MY WEBSITE IS BEING MOVED TO ANOTHER SERVER - SORRY FOR ANY INCONVENIENCE
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#5 User is offline   TimboBiotchie 

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  • Engine: v6 3.4L
  • Transmission: Manual 5-Speed

Posted 01 August 2012 - 04:17 PM

I was told the transmission is a 97 t-5.

I hope that answers your question. I know a decent amount about cars, but not a whole lot, learning as I go as I fix her up.
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#6 User is offline   Injuneer 

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  • Engine: 381ci LT1 stroker
  • Transmission: TH400 + O/D

Posted 02 August 2012 - 02:06 AM

The Trans AM (and all other 4th Gen V8's) did not use the T5 5-speed manual transmission. It's too weak. The V8's used a T56 6-speed manual. Only the base V6 cars had the T5 manual. If you replaced your original manual trans with another T5, I would think the VSS would be the same, but don't know for sure. But in any case, you don't have a 97 Trans Am tranny.

Maybe one of the V6 owners can help you.
1994 FIREBIRD FORMULA

FRED

Posted Image

381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

NO PHOTOS - MY WEBSITE IS BEING MOVED TO ANOTHER SERVER - SORRY FOR ANY INCONVENIENCE
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#7 User is offline   TimboBiotchie 

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  • Year: 1995
  • Make: Pontiac
  • Model: Firebird
  • Engine: v6 3.4L
  • Transmission: Manual 5-Speed

Posted 02 August 2012 - 08:35 PM

Ah ok, thank you for the input.

I'm going to see the guy I bought the car from next week to get a new windshield from him, and maybe I can get a little more info about the tranny. When I talked to him on the phone he seemed a bit rushed for time.

So hopefully I can get some more info next week. But for now I'll just continue to use my GPS to tell how fast I'm going.
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#8 User is offline   Injuneer 

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  • Year: 1994
  • Make: Pontiac
  • Model: Firebird Formula
  • Engine: 381ci LT1 stroker
  • Transmission: TH400 + O/D

Posted 03 August 2012 - 02:23 AM

You can put a box in the harness from the VSS to the PCM that allows you to calibrate the pulse rate from the VSS to the correct signal required for the speedometer to read correctly. I use this one to match a 40 pulse signal from my TH400 convertion to the 17 pulse T56 signal the PCM is calibrated for:

http://www.dakotadig...prod/prd126.htm
1994 FIREBIRD FORMULA

FRED

Posted Image

381ci all-forged stroker - 10.8:1 - CNC LT4 heads/intake - CC solid roller - MoTeC engine management - 8 LS1 coils - 58mm TB - 78# injectors - 300-shot dry nitrous - TH400 - Gear Vendor O/D - Strange 12-bolt - 4.11's - AS&M headers - duals - Corbeau seat - AutoMeter gauges - roll bar - Spohn suspension - QA1 shocks - a few other odds 'n ends. 800HP/800lb-ft at the flywheel, on a 300-shot. 11.5 @ 117MPH straight motor

NO PHOTOS - MY WEBSITE IS BEING MOVED TO ANOTHER SERVER - SORRY FOR ANY INCONVENIENCE
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