When I press the on/off switch, the cruise light on the dash does not come on, & I can't engage cruise. The light does work, it comes on at start up. I'm not getting any error codes, and I tried swapping switches with junkyard parts, but that didn't work. the fuse is good, does this sound like a servo problem?
I had a similar problem with mine. Started out that cruise would cut out randomly then stopped working altogether. Turned out to be a bad brakelight switch. The contacts for the cruise control are separate from the ones for the brake lights so your lights can work fine while the cruise thinks you are hitting the brakes all the time. Took the switch apart and found the issue, tried to fix the switch but ended up just buying a new one. Mine is a 93 so YMMV. Also I see you replaces switches but I took that as the on/off switch, if you already checked the brake switch never mind.
I have a niner like yours. Mine was a dirty contact in the switch. This is what fixed it for me:
Originally Posted by Foundrydude
Spray behind all the cruise switches with electrical contact cleaner, then work the heck out of em. Repeat two or three times. Allow to dry for several hours before powering up.
If you don't think that's it, break out the multimeter and start trouble shooting
__________________ March 2014 GCOTM. 1998 Deep Slate 5.9 On the Jeep:Hot intake, 52mm TB, Summit 8mm wires, catch can, 703s, insulated fuel rails, indexed Champions, Bilstein 4600s, Eibach lowering springs, Moog SS, Ironman mounts, Lotek 2GP, lots of gauges, sparkly paint. In the garage: M1 4bbl In the works: Addco/Hellwig sway bars, nitrous, full polly bushings, full exhaust, data logging, billet UD pulleys
Verify switches and clock spring... Measure resistance between clock spring connector Pins #1 and #2 with switches in positions shown in table below...
[*]First disconnect the negative battery cable, wait a few minutes for circuits to discharge[*]Remove steering column lower shroud cover[*]Remove the clock spring connector (white)[*]Check cruise switch operation with an ohmmeter between Clockspring side Pin#1 (PK) and Pin#2 (BK/LB).
mine ended up being a broken vaccum line to the servo. replaced it and its been working ever since
A broken vacuum line wouldn't show up as a problem to the PCM (it has no idea if the servo is getting vacuum or not), so you'd still get the cruise light on the dash. No cruise light means an electrical problem.