Diagnosing no 4wd

A friend has a 91yj 4.0 currently with no 4wd, not even the light. I know
it's the wiring harness or the actuator, but does anyone have any diagnostic
tips to isolate which one it is? Heck, the light could be a bad bulb....
But I put his jeep in 4 and it's definatly not engaging.
Nick


--
http://members.cox.net/nnote/

Trouble shooting guide:

http://www.4x4posi-lok.com/PDFs/TSG_jeep.pdf

Steve
http://xjeep.dyndns.org


Nick wrote:
> A friend has a 91yj 4.0 currently with no 4wd, not even the light. I know
> it's the wiring harness or the actuator, but does anyone have any diagnostic
> tips to isolate which one it is?

Usually that just means the vacuum connection fell off the front axle.
That would be the first place I would look anyway. The second place is
where the vacuum line passes the exhaust on it's way to the t-case. I
have seen a few touch there and melt.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

Nick wrote:
>
> A friend has a 91yj 4.0 currently with no 4wd, not even the light. I know
> it's the wiring harness or the actuator, but does anyone have any diagnostic
> tips to isolate which one it is? Heck, the light could be a bad bulb....
> But I put his jeep in 4 and it's definatly not engaging.
> Nick
>
> --
> http://members.cox.net/nnote/

Nick wrote:
> A friend has a 91yj 4.0 currently with no 4wd, not even the light. I
> know it's the wiring harness or the actuator, but does anyone have
> any diagnostic tips to isolate which one it is? Heck, the light
> could be a bad bulb.... But I put his jeep in 4 and it's definatly
> not engaging.
> Nick

Not sure if the vacuum harness for the '91 runs under the battery tray or
not. If so, it may be eaten up by acid.