Wiring to 242/ 231 transfer case?

I noticed '93 and up XJ's have a different connector/ more wires at the firewall connector going back to the transfer case than the 91/92 XJ model year.

Any idea if the wiring differences are "superficial"...meaning: Can a '93+ transfer case work in a '91 XJ without issue? Guessing the speed sensor insert/ plug is different and I can plug in my '91 unit with all the 4wd lights on the dash working. Please advise. Thanks

There is a difference between the 242 and 231 wiring for the additional indicator.

Just different connector if anything (did not think they changed in 93 though)

The full-time and part-time wiring is there for all of them, it is handled differently at the transfer case end of the harness

Would anyone happen to know the pin out/function for the mode selection switches on the 231 tcase ?

thanks
pete

I replaced the 231 in my '91 with a 242 from a '94 and it was all very simple.

The shifter is purely mechanical, there is nothing electrical there.

If the speedo connector is different then just physically swap them between the 231 and 242. It's just one bolt and a hold-down plate, then the speed assembly pulls straight out. Mark the positions before you remove them, so that you insert them correctly (gear sizes and position changes with different tooth-per-inch ratios); they only go in one of four ways but you need to get it the right way. I swapped mine out but I don't remember why.

The part-time and full-time lights are wired differently. The 231 with part-time only uses a black/red pair, and the circuit is closed by the switch. The 242 has a red /yellow pair and grounds to the chassis, so one circuit is grounded in part-time and the other is grounded in full-time. They also have different gender connectors, so you won't be able to plug them up wrong. The connector for the 231 is on the transmission wiring harness already but the plug for the 242 is in a different spot and you need a sub-harness to reach it. You don't say which one you are installing. I had to buy the sub-harness from the dealer ($13 IIRC) to get the 242 working. You will also need to install a bulb in the Full-Time spot in the dash if the jeep originally came with a 231.

In my situation i am trying to get a 231 to work on a ZJs 249 setup.

If i remember correctly, the 249 switch/harness is similar to the 242 in that it simply grounds to chassis activating the light. I am thinking i could simply ground one switch pin and connect the other to the part time pin on the current 249 harness ?

Pete