Speedometer Doesn't Work

[FireFighter32]

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?

[Silver88]

Happen to know what year the guage package came from?

[FireFighter32]

Everything came out the same 1994 Jeep Cherokee. Though at the time of the swap there were excess parts from other jeep projects, so the gauge cluster may be out of an automatic 94 Cherokee, or worst case scenario any cherokee with an non-mechanical speedo.

[FireFighter32]

Anyone have any idea here? I don't know how the speedometers work, so I don't know what to check!

[kastein]

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.

[Bounty Hunter]

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.

[FireFighter32]

Yes I did a full electrical swap. The Motor, Transmission, and transfer case are all new to the vehicle, as well as the wiring.

 

What do you mean by correctly clocking the speed sensor in the tail shaft?

[kastein]

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.

[1987Comanche]

The '94 Hi-Line cluster and the older Hi-Line cluster should have the same font. Why not just swap the mechanical speedo and cable back in? The driver for the mechanical speedo should be a direct drop in for the VSS.

[FireFighter32]

Being that I swapped everything last fall I no longer have the old speedo cable and mechanical speedometer.

[Bounty Hunter]

What do you mean by correctly clocking the speed sensor in the tail shaft?

[FireFighter32]

Thank you for all the help. Hopefully I will be able to check this out this afternoon.

[FireFighter32]

I looked at my t-case and I didn't see the raised dot.

[Bounty Hunter]

It's not always there, but you should always put the correct number range in the 6 o'clock position in the hole.