knever3

Huge update, I called in a little favor from my friend Jerami today and we determined what the problem was together. It was a long hunt but I think we got it. For starters we tested a lot of wires going to and from the brake switch, cruise control, and comfort/power switch. When we were probing all the wires it was obvious that the signal from the brake switch/cruise and comfort/power switch wasn't making it to the TCM. We discovered these two plugs that don't go together. I think one was C115 and who knows what the other one is, we never found it! The flat 3 pin female connector has wires tan, light blue/black, and black/yellow. It just so happens that the power/comfort switch has a black/yellow wire too and a tan. Jerami made a jumper for the two plugs while I watched my son for a while. This is the flat 3 pin female connector. Now onto the second plug. It has 6 wires in it, male with three wires that we could trace. Tan, light blue/black, and black/yellow. Sounds familiar, right? Well we spent some time with continuity and the wires go from the aforementioned switches to the TCU. This is the 6 pin plug, the three wires we tracked down, the other three who knows? So onto the third piece of the pie. There are two brown brake switch plugs and a jumper for the clutch if you have an automatic. We measured the jumper and it contributed 33 ohms of resistance so we cut it out and spliced it together getting rid of that unneeded resistance. Nest was the second brown brake switch. It ended up doing nothing at all. We left it unplugged. The next was that clear plastic plug that goes to the cruise control vacuum brake switch. I didn't trust it so I unplugged it and Jerami made a jumper for it. After the upteenth test drive the torque converter finally engaged. Now, we did probe the C14 on the TCU and supplied 12V earlier to lock it up to make sure the solenoids were working in the trans. It locked up as expected. The fight was why were the wires missing in the first place. This is the jumper to the cruise control brake switch Jerami made up. It looks like I need two things, well actually three. First a new cruise control brake switch. Second, a jumper for those two plugs (and find out if the other three wires are necessary for anything else.) And three a new cruise control module. We unplugged the board and there was some corrosion on the terminals on the board and maybe a short sometime long ago. Does anyone have any of these items that want to sell me so I can get this thing on the road? Thanks again for all your help along the way, you have been instrumental in determining the root cause(s) of this conundrum.

Ok, digging into it where does the blue/yellow wire go from the TCU? It seems I'm missing a wire that the TCU is supposed to see the brake switch. I really need to have all the FSM's for this thing!!

Ok, last night I jumped the second brown connector to the brake switch. I went for a test drive and the torque converter didn't lock up. The search continues this weekend. :(

Yeah I don't have the dual switch, I copied someone else's picture but I will just jump them. Thanks for the info and I will test this out this weekend if time allows.

Thanks for the digging guys. So I have a couple of questions as to what to do next. I have a seperate cruise control module that is installed with its own brake switch and vacuum hose above the normal brake switch with a blue/bk and black wire. Maybe I need a different cruise control? As I read your post it looks like I need the double ended brake switch like this picture so both brown plugs can be plugged into the same switch. I would expect that just running a jumper would work the same way. Image Not Found So what wire is supposed to be "seen" at the C10 on the TCU that's supposed to be the brake switch? I can't find a diagram that links the brake switch to the cruise and to the TCU. I need to go to a few salvage yards and see what's supposed to be in this truck.

Don, I tested the wires at the firewall and I did get the 12-16 ohms, when I tested the same wires inside the cab at the TCU I got 26-32 ohms for the same three. So I have a few pictures tell me what brake switch plug I am supposed to be using. The one I am using makes the brake lights work. It's pink and blue/black. This is the one I have the two wires from the aftermarket brake switch in. The second exact same brown plug is not plugged into anything. It's pink and blue/white. The third thing is my cruise control that's never worked. It has its own plunger and electrical plug and when I test it I get no voltage on either wire regardless if the brake is depressed. The wires are blue/black and black which tests as ground. So to recap I have two identical brown plugs shown in this picture. I don't know what wire is supposed to be going to C10 on the TCU, but I think it's not getting the brake switch signal so the torque converter is not locking up at all. Thoughts?

Wonky huh? C10 is not wht/pnk in my truck, it's blue/yellow. When I test it I get nothing either when the brake is depressed or not. Edit: It looks like that wire color is common with another year, I see that in the '89 manual that's the color it's supposed to be. I also learned that it doesn't come from your brake switch that runs the tail lights, but the switch that's on the cruise control vacuum module. I will look into that one I guess. The Saga continues...

28,28,32 ohms respectivly. 14,15,16 to d16 pin

I'm thinking it has something to do with my brake switch input. I have a '96 brake booster and MC installed and I have an aftermarket brake switch. The brake lights come on fine but maybe the computer doesn't show the switch input. There are two of the exact same brown plugs under the dash and only one seemed to work with the switch. I am going to get the wire colors and look in the manual to see if that's the problem.

Ok i got 30,26, and 26 ohms for pins 14,15, and 16 with my probe to ground, now what?

It sounds like you might have a bad fuse box. Is your Comanche a manual? If it is there is a good chance the clutch master cylinder is leaking onto your fuse box causing a number of bad things. The fluid will melt the plastic and it can ignite with a short or an arc. The ground will be behind the tail light after you remove it. If you can take some pictures of your fuse box we can help you out better.

Nice work!

I wouldn't run ethanol at any time. It will rot your rubber lines and Orings plus your truck will run lean because there's not enough BTU's, your computer is not setup to add more fuel.

I second the one piece rubber gasket, when you are in there might as well look at the rear main. If you have oil leaks make sure your breather pcv systems are working. If they aren't you will push past gaskets all the time because the crankcase will be under positive pressure.

Great idea, I really couldn't tell you when it stopped working. After I did the swap it never did run right and I put only a few miles on it. I will check the TCU tomorrow if I get a chance. I swapped the entire engine harness, drivetrain etc from a '90 Cherokee. In the last week I changed the engine harness again because I wasn't happy with the way I did it last time. i went through the harness very meticulously.

No problem, sometimes that's where you find your answer!! Anyway, I received the alternator today and checked the voltage before and after I installed it. Here's what I am working with, new vs. old: Direct bolt in, Before battery voltage Engine running After 100 amp Bosch alternator install, the hum from the alternator was still there faintly but it still hums. Turns out my alternator wasn't bad afterall, just feel better with a 100A. Well a little piece of mind I guess. I'll update this if I do find the Optima is not keeping a charge when I actually daily drive it.

Well that won't matter if I am testing the plug disconnected from the trans anyway, right? I haven't tested the engine harness pin to see if that has ground, but if the solenoids are working it should. Maybe the harness for the trans is bad? I will check into that, feel free to point me in any other direction otherwise. Thanks again.

Ok, I was wrong in my initial measurements. I probed the black connector. After I re-read all the post I measured it again. This time with the light gray or (white) connector. I first measured all the above and got open on all. Then I measured "B" to the battery ground and got an open. So it looks like the wire that is supposed to be the ground for the solenoids is not registering. So I measured battery ground to all three pins. G 12.7 ohms F 13.8 ohms E 17.8 ohms

Ok, from B to E I get an open circuit. So it looks like I will need to replace the solenoid(s). So a couple of questions, where should I buy them from? Should I replace all of them or just the one? I have another trans in the storage unit so I could source one from there to be cheap. I looked online and can't find a good place to buy new ones. Advance can't even order them and Autozone wants $329 for something that says solenoid. I don't trust them. Thanks for the advice again!!

Advance auto online direct ship to house only.

It's a Jeep Miracle!! I bought a used OE '93 throttle body and exchanged my broken IAC for a new one and installed it. I adjusted my TPS to spec and adjusted my Hesco adjustable fuel pressure regulator up to 39psi with the vacuum disconnected. The truck idles beautifully smooth at about 500rpm or lower if that's accurate on the gauge. It goes down the road awesome, the exhaust is much quieter if that makes any sense. It had a nasty resonance at about 1700rpm that you go by. It doesn't droan all the time anymore. I still don't think the torque converter is locking up, maybe I need to adjust my trans cable? I don't know how to do that though (yet). It seems to me that the line pressure can be increased because it shifts slow even in the performance setting switch. It's an old trans, has over 200k on it. Thanks Don for the great advice!!! I will call the manufacture of the throttle body and see what they can do for me. I will get that BBK one for sure. It seems like the engine could use a lot more air. It has a tick on the top end I will have the engine builder listen for when I can get down there. I just want to make sure it's ok. I don't hear any valvetrain noise on my '99 so there shouldn't be any with this fresh stroker. So I just need to figure out if the torque converter is locking up or not. I will post a video of driving if it will help you with trouble shooting that problem. Let me know what to do next guys.

I was tinkering with the Jeep today and noticed a high pitch wine under the hood while the ignition was on. Sometimes this is normal to an extent but this was overbearing and obnoxious since I was testing my TPS and other sensors for a while. I tried locating it and thought it might be one of the relays or the battery. It ended up being the alternator, I unpluged it and the sound went to zero. I ordered a new Bosch 100 amp to replace the pitiful 61amp OEM. We'll see what difference that makes. I will post the results of the swap and differences in voltage if any. I believe one of the diodes were going bad that was resonating possibly, who knows.

I am using the throttle body vacuum port for the MAP. I haven't checked the MAP voltage out. I wouldn't be opposed to trying a different throttle body, or maybe I can call the manufacture and have them do something for me, like refund my money!!! I agree making the end user take a hack saw blade and assembling the part does sound crazy, I guess it would save money on their end, but I don't think it's nice for the customer to use old parts and modify them to use on their brand new casting. I'll check out BBK. Thanks for the advice Don, I will work on that.

Yeah I wasn't happy with the way the throttle butterfly fit, there is a gap around the whole thing. It doesn't touch the sides at all. That could be a BIG part of my problem. I used what they sent me and followed the directions to a T. (Whatever that means) Yes I used the renix IAC and TPS, The IAC just bolts on no different. I used the HESCO adapter for the TPS for what it's worth it doesn't allow me enough adjustment to get the recommended voltage. That's why I had to adjust the mechanical stop and that compounded my problem. It also whistles when I put my foot into it. Which my wife can't stand!!!! I am using a new renix O2 sensor to send to the computer and a second O2 for the wideband O2 digital readout in the cab. I don't know if my MAP vacuum is good or if the sensor is good either. I guess I could try a newer MAP to mount to the throttle body if they are no different. That would clean things up for sure.

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