Raymond K Essel

Well, looks like both engine mounts are in pretty sad shape. Not completely separated, but the passenger's side has a fissure that runs from front to back at the 2 o'clock position (looking from the front of the vehicle). Driver's side is in mildly better shape...which means it's also bad. Guess I'll start there! I'll probably do the trans mount too since none of these mounts are terribly expensive.

All, thank you for the many helpful responses! I've bench-tested the CAD and it is fully operational...about the only thing aside from the clock that meets that description (I kid...it's in a heap of hurt, but it's no parts truck). I'll inspect the t-case linkage area for rot and mis-alignment, then go through the t-case linkage adjustment process and report back. Hopefully it's solid and simply out of adjustment! Would be nice to fix something on this thing for free.

The reason I think it's in 4WD is because the front drive shaft can't be turned by hand and when I drive the thing crow-hops like it's gonna tear itself in half. If the t-case was actually properly in 2WD wouldn't I be able to get under the vehicle and spin the front drive shaft while the truck is stationary?

If the t-case shifting is purely mechanical, what is the vacuum switch on the t-case for? (Seriously...honest question there.) The case does shift into neutral and 4 low. I did it without starting the vehicle soooo...guess you're right about the vacuum switch not playing a role in shifting. Good thought about the case swap. It is in fact a 231 though. This truck is such a basket case I wouldn't have been surprised to find anything under there.

Correct gogmorgo, stuck in 4WD. I understand that the CAD in these things is problematic, but my understanding is that their main failure mode leaves the vehicle WITHOUT 4WD. Ideally I'd like to know if I can separate the issue to the mechanical t-case internals vs the vacuum supply side via a hand vacuum pump on the t-case vacuum switch. If I can pull a vacuum on the t-case vacuum switch and momentarily unlock the front drive shaft, then I'll hunt down where my vacuum supply issue is...but I don't know which vacuum switch port(s) disengage the front shaft...or if that is even a legit diagnostic method.

Ok, there seem to be plenty of people around here with Comanches that won't shift into 4 wheel drive, but I'm having the opposite problem. I can't get my truck to shift back into 2 wheel drive. For short trips I've been pulling the CAD connector off to allow the front wheels to spin independent of each other, but I'd really like to have this thing FIXED! The front drive shaft does not spin freely; it's always locked in no matter where the shift lever is located. The truck is an '87, 4.0L, automatic trans, Command-Trac. Linkage feels tight and responsive to the lever (moves full stroke). I believe the truck has the wrong gauge cluster in it because the "Full Time 4wd" light is constantly lit, but that isn't even an option in this truck (no Select-Trac case). The hoses running to/from the vacuum tank behind the front bumper were in sad shape and my not have been connected properly when I got the truck. I've replaced them, but don't know if they're going to the right places. Here's my question...can I apply vacuum with my hand pump to one of the ports on the t-case vacuum switch to see if the problem is a vacuum supply issue or an internal t-case issue? I don't know what each of the 4 colored lines on the vacuum switch is supposed to do, or if vacuum needs to be seen on multiple ports to get the t-case internals to come alive. I appreciate the help!

Regular Guy, thank you for the 4wd light explanation! Next time I take a look at the engine bay I'll check out that switch. The whole "how it happens" thing has been a little mysterious to me so far. This helps a lot! As for the brake lights: I believe the brake light switch is firmly attached. I found the connector near the spare tire and probed the input side while someone applied the brake. I've got battery voltage on the grey/white and brown wires with the brake pedal depressed, and 0V when the brake pedal is not activated. The really confusing part is my turn signals work, which uses the same filament in the tail light bulb as the brake light, right? The sockets look a little melted and nasty so maybe they're damaged in a way that only affects the brake input circuit...tail lights and turn signals unaffected. Seems like kind of a long shot, especially on all 4 bulbs, but I'm not sure what wire at the socket is responsible for brake light signal, so it's tough to check at the socket for B+. The color labels in my Haynes manual don't match my specific vehicle. I think I might replace one socket (~7 bucks) and if that works do the rest.

Wow, man I am so sorry guys! I had to move after I posted back in March and that really disrupted my wrenching time! Just to fill you in on how things are going... The front drive shaft can be spun by hand when the vehicle is both off and running. After much work with the idle I was finally about to drive it around yesterday (~15 miles total) and it is definitely NOT in 4 wheel drive, though the dash reports I am. I don't know whats going on with that yet. Also, from previous experience (I had an '89 XJ about 10 years ago) the Full-time 4wd offered by the Selectrac case lights a green 4wd light, while the part-time offered by the Commandtrac lights a yellow 4wd light. My Comanche has the Commandtrac, but a green 4wd symbol is (erroneously) lit on the dash. Am I off base with this memory? Maybe it's a swapped dash. Judging from what I've seen on this vehicle so far nothing would surprise me. I haven't yet done that CAD modification, but I am planning to. I'm still working on the things that are keeping it from being road-worthy. At this point that involves figuring out why the 12 volts at my "near the spare tire" connector isn't getting all the way to the brake light bulbs. I look forward to the day the truck operates as it was designed to!

Hi everyone. First time poster here. I bought my Comanche a few months ago from a guy who bought it with the intention of fixing everything up, but then I guess lost interest/lacked knowledge, and wound up unloading it for cheap. I've been working through many of the problems he avoided (and some of the ones he fixed... ...) but one so far has left me baffled. The thing is stuck in 4 wheel drive! It has the NP231 (Command Trac) and when I start the vehicle it shows 4WD on the dash, plus, when I drive it around the block I can definitely feel crow-hop going on. With the t-case selector in 2wd it's in 4wd. With the selector in 4wd high, it's in 4wd. I think it switches to 4 low with the selector, but haven't really checked that. Regardless, the case won't switch into 2wd. In order to get the truck home from where I bought it I tried everything I could to get it into 2wd. I went in reverse and backed up, I tried turning while in reverse, doing 30 I dumped the trans into neutral, played with the t-case lever, and then back into drive, I got under the truck and manually moved the adjuster, I banged on the adjuster with a rubber mallet to make sure it was making full travel (I think it was)...I've still got nothing. In order to get the truck home from where I bought it I wound up pulling the vacuum coupler off the CAD which turned off the dash 4WD light and eliminated crow-hop (it was definitely in 2WD) and then I drove it 150 miles home. When I got home I tried connecting the CAD vacuum once again to see if it shook free of 4WD and even after all that it still hadn't. I took the CAD fork assembly off and pulled vacuum on each of the ports to see if it were hanging up somewhere and it moves freely in both directions. I think part of the problem is I don't fully understand what happens when I pull the t-case lever. Obviously the front drive shaft becomes engaged, but what activates the CAD? What switches the vacuum from one side of the CAD diaphragm to the other? Where is that valve/switch/doo-hickey located? Where does the 4WD dash light signal come from? I obviously interrupted it by removing the vacuum coupling from the CAD, but the mechanicals in the t-case are still in 4WD orientation right? Can someone supply a play-by-play of whats supposed to happen when I throw that t-case lever into 4-hi? Or at least a list of things I may want to check. Anyway, this general lack of 4WD understanding is keeping me from driving my Comanche! So...any help is much appreciated. Thanks guys!