4wd dummy light question

[mikekaz1]

1991HO 2wd converted to 4wd with renix tcase. Is it possible to get the 4wd dash light to work? How does it actually function? I've never noticed a switch other then the speedo going to the case on any of my jeeps. Being originally 2wd would that wiring even be there?

[cruiser54]

231 or 242 case? 

[mikekaz1]

231

[cruiser54]

231 out of a Renix era had a vacuum switch to activate the front axle disconnect and dash light.

 

Since mid 91 and later had no vacuum switch, but an electrical switch, perhaps that would work on your 231?

 

That said, I could care less about dash lights with a 231. I just look at the indicator near the lever.

[mikekaz1]

I don't care that much, my TJ light has never worked either. but was curious if the electrical wiring was even on my MJ since it was 2wd. or if the renix 231 had a electrical switch or could even have one installed

[gogmorgo]

Automatic or manual?

 

This is one of the connectors for my automatic transmission on my '91 factory 4x4, the one the 4x4 light(s) go through, and also the shift solenoids, I think. Actually this is off my '93 parts XJ, also a factory AW4 4x4, but everything is pretty similar.

 

It's near the transmission dipstick tube, near the firewall on the passenger side of the head. Here's the half that goes down to the tcase.

 

 

Here's the connector on the MJ with everything hooked up. (and the motor in place). There are two similar plugs, the other's for the neutral safety switch.

 

There are wires and vacuum lines in the loom for that connector. One of the vacuum lines connects to the engine bay vacuum harness near the connector. Two of the wires, an orange and black, branch off and go to the CAD, along with the vacuum lines that actuate the CAD. Those two wires connect to the switch on the cad, and are for the 4x4 light.

 

Down on the back of the transfer case, this is where things hook up. The top connector is for the speedometer, an unrelated system with a separate harness. The bottom is the vacuum switch that actuates the CAD.

 

 

This is what the non-cad version looks like on the back of my '93 242. Apologies for the poor lighting and awkward angle. You can see the 4x4 light switch and wires beside the fill plug, just below the identification tag.

 

 

Going back to the '91, 231 drivetrain for example purposes (easier to take pictures of it), this is where the 242's 4x4 wires connect to the harness. It's there on the '91, even though it has the 231. It's on the driver's side, at the top near where the tcase bolts to the transmission. The other loom visible is for the shift solenoids, and they split near the shift lever on the side of the transmission.

 

 

I understand that on the later, non-cad (231 equipped) models, there's a separate connector here for both transfer cases, but I can't confirm that because I didn't check the '93 trans before I put it in.

But when I swapped in the '93 4.0/aw4/242, the trans/tcase connector (that I pointed out above) plugged right in. The part-time 4x4 light works in 4hi (part time) and 4lo, and goes out in full-time 4hi. I imagine it would just take a bulb to get the full-time light working, but I haven't pulled out the cluster to check.

 

I don't know if it would work or not, but the newer electric switch may swap in place of the vacuum one on the back of the tcase. It looks like the switch would just screw out/in. If that's the case, the actual wiring of the harness should be fairly easy, just plug it in.

Of course this whole post might be wasted if you've got a manual that doesn't have the trans connector, or if the 2wd trans connectors are different. You probably also don't have a bulb in either 4x4 light.

[mikekaz1]

I di have the aw4   and thanks that actually some really good info!   I know mine has the 4 hole vacuum switch in the back.  so that may be able to just be unscrewed and then the electric 4wd sensor screwed in? correct,

[gogmorgo]

I can't promise that it'll work, as I simply don't know. I could go out and try to pull the vacuum sensor from my 231 if I have time tomorrow (too dark now), but I'd rather not risk doing something unknown to the one in my 242 which is in the truck.