quik questions - LT1 T56 VSS & speedometer
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From: check under the car
Car: White 25th Anniversary RS
Engine: lt1
Transmission: t56
Axle/Gears: 4:10
quik questions - LT1 T56 VSS & speedometer
Will the 95 lt1 pcm and t56 play well with the stock 92 camaro speedo? Or do I need a dakota box?
Joined: Mar 2000
Posts: 43,187
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From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Need someone to verify this, but I believe the PCM speedometer output is 4000 ppm like the 3rd gen speedometer.
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From: check under the car
Car: White 25th Anniversary RS
Engine: lt1
Transmission: t56
Axle/Gears: 4:10
Re: quik questions - LT1 T56 VSS & speedometer
Missed that part
All 3rd gen electric speedos that Ive seen require 4,000 PPM input. The best I can tell is LS1s use a 40 pulse per revolution input and change it to 4,000 PPM output to the speedo. The cruise output is 2,000PPM just like 3rd gen cruise
Regardless of older 3rd gens using a 2,000 or 4,000 PPM signal, the value can easily be changed when tuning the LS1 PCM to make what you have work
The dakota box is used to change LT1 T56 11/17 pulse per revolution signal to 2,000/4,000PPM 3rd gen signal when keeping the TPI
All 3rd gen electric speedos that Ive seen require 4,000 PPM input. The best I can tell is LS1s use a 40 pulse per revolution input and change it to 4,000 PPM output to the speedo. The cruise output is 2,000PPM just like 3rd gen cruise
Regardless of older 3rd gens using a 2,000 or 4,000 PPM signal, the value can easily be changed when tuning the LS1 PCM to make what you have work
The dakota box is used to change LT1 T56 11/17 pulse per revolution signal to 2,000/4,000PPM 3rd gen signal when keeping the TPI
Joined: Mar 2000
Posts: 43,187
Likes: 45
From: Littleton, CO USA
Car: 82 Berlinetta/57 Bel Air
Engine: L92/LQ4 (both w/4" stroke)
Transmission: 4L80E/4L80E
Axle/Gears: 12B-3.73/9"-3.89
Well, now that I see pocket's post again, it may not be correct. Actually sounds like the LT1 output needs to be converted.
With all of the LT1 swaps that have been done, I would think the answer would be easier to find. I have no personal experience to relate, however.
With all of the LT1 swaps that have been done, I would think the answer would be easier to find. I have no personal experience to relate, however.
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From: Tampa, FL, USA
Car: 93 240SX
Engine: LQ9
Transmission: T56
Axle/Gears: 3.54 R200 IRS
Re: quik questions - LT1 T56 VSS & speedometer
Yes it will work directly without a converter.
You will have to splice the output from the pcm directly to the wire from the buffer box->instrument panel if its a TBI car.
You will have to splice the output from the pcm directly to the wire from the buffer box->instrument panel if its a TBI car.
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From: Chicagoland Suburbs
Car: 1989 Trans Am GTA
Engine: LT1, AFR 195cc, 231/239 LE cam.
Transmission: M28 T56
Axle/Gears: 3.23 10bolt waiting to explode.
Re: quik questions - LT1 T56 VSS & speedometer
I'm not sure about the 94+ T56's, but the 93' T56 with its 11ppr ratio does kind of work with the thirdgen electric speedo.
Its about 6% high at all speeds. At an indicated 80mph I'm doing 75mph.
Its about 6% high at all speeds. At an indicated 80mph I'm doing 75mph.
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