princeps

Here's a photo of a hydra head at the end of a harness inside the engine compartment of an 86 XJ 2.5l.

86 XJ 2.5l harness end Engine Compartment under blower motor

It is next to the firewall under the blower motor on the passenger side. (Here's the best doc I can find.)

The blue labels mate with other connectors on other harnesses.

The white labels are what I'm sure about (though what is controlled by the electrically activated vacuum value is unknown).

Dangling loose unconnected to anything are the two yellow unknowns.

Can anyone tell me what these two connectors are for?

Hint: One might be "4WD indicator light switch", if you believe the drawings.

Thanks!

DFlintstone

Yer 86 might have the same blue vac switch on the passenger side firewall as the later if you have the vac-disco on the RF axle. I have an 84 right here but am not going out just now.

Jeep Driver

M1 should be for the hood light, you likely do not have.

F3 should be for the EGR purge valve solenoid.

princeps

Thank you very much, Jeep Driver and DFlintstone!

BTW,the ERG purge is vacuum driven on this engine, and on the other side of the compartment. I suppose the harness allows for a later model with an electric solenoid purge valve.

DFlintstone

Went and looked. My 84 has a black/yellow stripe to the blue vac switch for the 4 wd light. (right near the blower). I don't see that in your photo. You're welcome, good luck!

princeps

The blue vac switch is truly a switch, not a solenoid to control vacuum.

First, the previous owner made a lot of "customizations", and I don't believe they put it back together correctly. The current task has been to get the HVAC venting/controls working.

I'm 99% sure the vacuum reservoir canister wasn't connected to a vacuum main line.

The blue switch was connected directly to a vacuum main line. I suspect it should connect to the 4WD transfer case.

And I can't find pictures/service part locations/tube or physical cable routing diagrams. This has become a giant logic puzzle.

Anyway, the picture has a white F1 and a blue F1. The blue color is wrong, because there isn't a matching connector for it (that I can find).

The yellow/black wires to white F1 connect to the blue F1, like white is in the middle of a daisy chain ending at blue. Therefore I suspect blue F1 is for a version with a different 4WD engagement mechanism (perhaps electrical vs vacuum)? Haven't researched 4WD activation.

What would help is a good picture of the blower motor area and below, showing the colored PVC vacuum hoses.

DFlintstone

I'm thinking that your "smart" thing can't see the link in my signature> https://www.cherokeeforum.com/f23/te...itings-136452/

There's your vack diagram in there. Constant vacuum to that blue switch should have had the 4 wd light on all the time. (wrong)

Listen. The disco has three lines on it. One won't shunt vacuum up to the switch until the fork in the disco has moved over. (a solid confirmation it's in). Vacuum to the Transfer Case switch comes off a "Y" there behind the trans dipstick. That Y is on the large line that comes off the rear of the intake, crosses over at the firewall then goes all the way forward to the vacuum ball, (and it's check valve in there).

It's the small rigid black line coming back from the vac ball that powers the vent flaps.

princeps

Thank you for you patience and the most helpful link. We're moving forward again.