2004 Speedometer Calibration

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Apr 9, 2021
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North San Diego County
I haven't seen calibration done with 12oclockLabs, so here is some info for anyone interested in calibrating your speedometer. The calibrator can be found at 12oclockLabs website. The correct model is "U1" and cost $79.99 + shipping. I originally ordered the wrong one but the customer service is awesome and they are very informative. In short, this unit allows you to make changes from +/- 99.9% and wont require a trip to the dealer to flash. It will also allow you to reprogram in the future if you changes tire size. When I regeared to 4.10's with 245's, my speedometer was almost right on. After installing 295/70/17, I was off by over 12%. I wont go into detail of how to program unless someone is interested but 12oclockLabs does have a helpful video explaining the procedure.

1) Remove the panel below the steering wheel and horizontal panel at the bottom.
2) Remove the 26 pin BCM connector located at the back of the fuse block.
3) Cut the green/yellow wire.
4) Connect the white wire from the U1 to the cut wire on the connector side.
5) Connect the blue wire from the U1 to the cut wire on the harness side.
6) connect the black wire from the U1 to ground.
7) Connect the red wire to switched power.
8) Program device based on the percentage discrepancy between speedometer and GPS.
9) Install complimentary horsepower sticker.


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