Speedometer calibration

[pnhigg]

I just got my truck on the road.
92 SWB with a 5.3/T56 combo with a Nelson tune.
I runs great and I have everything up a running except the A/C. I still have to make some brackets.
All my gauges are working properly, except the speedo is way off.
I think the fastest its read is about 30mph.
I know it has to be recalibrated, my question is, what does it take to do it?
Maybe be an obvious answer just not sure in the hybrids.
Thanks

[RedHeartbeat]

You should have a speedo wire coming from the pcm that needs to be hooked to the lead going the the gauges. Hook the single lead wire directly to the gauge side of the white box behind the glove box. If you need the exact color of the wire to connect I can get that for you.

[RedHeartbeat]

The wire from the gauges to hook the PCM output is light blue with a black stripe. the one from the PCM is green with a white stripe coming from pin 50 on the red connector if the PCM is newer than 1998.

[pnhigg]

Thanks,
I'll try it tonight or tomorrow, and let you know.

[pnhigg]

What am I doing wrong?
First I tied the green and purple twisted wires from the engine harness in with the green and purple twisted wires from the original truck harness.
Then today I jumped the pcm output wire to the blue/black stripe wire on the truck, and both ways, my speedo only reads about 1/3 what it should.
Any other ideas of what I could have screwed up.

Thanks in advance

[RedHeartbeat]

The light blue/black wire has to be disconnected from the white box entirely, unplug the pin/terminal.

You might want to disconnect the purple/yellow wires from the original truck harness from speedo pickup sensor. You may only need that for anti-locks and cruise. I'd isolate the white box from the input data until you find out for sure that is what is causing the speedo issue.

[pnhigg]

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jun 21 2006, 04&#58;56 PM) [snapback]55950[/snapback]</div>

The light blue/black wire has to be disconnected from the white box entirely, unplug the pin/terminal.

You might want to disconnect the purple/yellow wires from the original truck harness from speedo pickup sensor. You may only need that for anti-locks and cruise. I&#39;d isolate the white box from the input data until you find out for sure that is what is causing the speedo issue.
[/b]

Thanks,
Still no luck.
I cut the light blue/black wire at the vehicle speed sensor buffer box (the white one) and hooked the green/white wire from the pcm to it. No change.
Then I unplugged the entire white box and no change either.
So far I get the same result no matter which way I try.
Could it be that the pcm output is off that much? or is that a crazy thought.

Thanks again.
If anyone has other ideas, I&#39;ll be glad to try.

It&#39;s fun to drive, just be nice to know how fast I was going.LOL

[RedHeartbeat]

What transmission are you using? was it with the LS1 or is it from an earlier vehicle? I think the LS1 expect 20,000 pulses per mile. Earlier version had less.

[pnhigg]

<div class='quotetop'>QUOTE(RedHeartbeat &#064; Jun 22 2006, 05&#58;08 PM) [snapback]56032[/snapback]</div>

What transmission are you using? was it with the LS1 or is it from an earlier vehicle? I think the LS1 expect 20,000 pulses per mile. Earlier version had less.
[/b]

The original transmission was a getrag 5 speed.
The t56 that I have is from an LS1.
The pcm was from a 5.3 and a 4L60e, but when I had Allen program it, I told him that the transmission was being changed to the t56. Not sure if that would change anything.

Thanks again.

[RedHeartbeat]

Did you tell him what gears you have and what diameter tires? He had mine within 5%. I had to use my GPS to figure out it wasn&#39;t exact. He can fix the PCM if it&#39;s off. You might have to remove the tailhousing off of the transmission and count the teeth on the speedometer reluctor if he doesn&#39;t get it close on your next tune. Sometimes people will do funny things to their cars to keep the mileage low on the odometer. Grinding off every other tooth on the reluctor will do that, cutting the miles in half on the odometer.