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Speedometer Doesn't Work


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Last fall I swapped a 4.0 H.O., AX-15, and an np231, along with a full wiring swap into my 89 Comanche. Almost a year after doing to the swap I am finally tying up the loose ends. My speedometer has not worked since the swap. What makes the speedo work? What could be wrong? Anyone have any suggestions?

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Did you swap the wiring harnesses and such as well? The signal from the VSS (sensor on the transfer case tail housing) needs to make it to the speedo/odo input on the gauge cluster somehow, if you left the stock 89 instrument panel and interior wiring harness in place that's probably the issue. It will be easier to wire that signal independently than it will be to swap the whole harness as you will need to modify the 94 XJ harness to fit an MJ.

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Both the '89 and the '94 Speedos are driven by the speed sensor in the tailshaft of the transfer case. The '89 is mechanical (cable spins) and the '94 is electronic (all wires). If you have the complete '94 setup, it's likely something as simple as correctly clocking the speed sensor in the tailshaft in order for the speedo gear to contact the mainshaft in the transfer case.

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If you never took the VSS out of the transfer case and just transferred the whole thing you can disregard that part most likely.

 

I'm betting the signal simply isn't getting from the VSS to the gauge cluster, or the +5V sensor power wire isn't connected to the VSS... where it stops is the part to figure out now.

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