Hey I need help diagnosing a transmission problem. I think I have an idea of what is happening but I want to get your opinion. I have a 1998 auto cherokee with about 180,000miles. Ill start my jeep up and start driving after a quick warm up. Everything is shifting fine. Once I get onto the highway it shifts smoothly up into overdrive. But its not in overdrive for to long when I feel what almost is like a down shift. My RPMs kick up to about 500 to 700RPMs higher with out moving the throttle. At first I thought the trans shifted out of overdrive to 3rd gear. Just to check I moved the shifter from drive to 3 and it down shifted so it wasn't the transmission shifting. The fluid is clean and full. My trans temp gauge (aftermarket) is saying its not over heating and staying at its normal temp. The only thing I can think it might be doing is the torque converter is coming out of lock up. If I turn the jeep off and start driving again it will repeat that cycle. When this happens it just feels like something is off. RPMs are higher then normal and it doesn't have the get up and go (on the highway) it normally does. If anybody has had or heard of this problem before please chime in. I do a lot of highway driving and this is going to kill my gas mileage. Need to fix it ASAP!

 

Last time you adjusted your detent was...

 

I'm pretty small fish here. Codes? The parts store might check them free. I adjust my "kickdown" cable with about zero play. There is a button on the housing to free it for adjusting. There is an "Automatic" procedure, someone might post.

Brake petal got two switches on it? If so the second, white one breaks the circuit to the TC lockup solonoid. (I think). Maybe something to consider....

 

Haven't adjusted my kick down cable recently but I was able to barrow a scan too from work. The TCM is seeing proper brake pedal operation, the TPS doesn't have any open spots in it, but I did find a code in the TCM. Its P1748 solenoid C shorted to ground. After a little research I found that solenoid C is the TCC solenoid. So I will be looking for rubbed wires in the harness to the trans but I have a feeling it will be the solenoid.

 

Good work, great info, thanks! Let us know...

 

Just got the flow chart for the diagnostic for that code off of Alldata. Have a alittle connection through work

 

Id recommend doing all solenoids if your doing one .

 

where is a good place to get a rebuild tranny for my 91 auto on line

 

Howdy Caleb. You will probably have better luck posting on the main forum. (or maybe in "ask a question" thread.) Here it's just a few of us with BamBam's issue. In any case, Welcome!

 

AW4 "trivia" C/O Radi.

AW4 operation..Radi
1st gear - solenoid 1 ON, solenoid 2 OFF
2nd gear - solenoid 1 ON, solenoid 2 ON
3rd gear - solenoid 1 OFF, solenoid 2 ON
4th gear - solenoid 1 OFF, solenoid 2 OFF
Lockup - Solenoid 3

 

Well after some diagnostic work, it seems like the TCM is the problem. It would be nice if its the TCM because I will not have to drop the trans pan. Guess I'll find out soon.

 

Before you tear apart the tranny, check your brake pedal switch for proper adjustment.. when you touch the brake pedal, the brake switch turns on your lights, but it also disengages the torque converter and overdrive.. I suppose the switch could be telling it to unlock during normal driving and maybe cause the code? Just a guess

 

I haven't done it personally. I've seen posted you can check resistance of the individual solenoids. If I were going at it with no other info, I'd compare the ("C, shorted to ground"), with the other two. Unplugged of course.

 

Brake pedal switch is working normally. I was able to see the brake signal being sent to the TCM through the scan tool.

Smart minds think alike. lol According to the flow chart that I was using (from alldata) says, it doesn't want to see less then 5ohms anywhere in that circuit. I checked and got 20ohms for solenoid C and since I was there I check A and B too. They were also 20ohms. The harness going to the computer had 34kilo ohms. Unplugged the computer and retested that harness and it showed an open circuit. So according to the flow chart it I have a bad TCM since there are no shorts in the solenoid or harness. It makes sense because every time I start or restart my jeep the first time it goes in to OD it will go into lock up. Even if I just pull over turn off and restart the motor. It will only stay engaged for about 15seconds tho.

 

No braner there. We need Chuck. I will shine the "Radi" beacon into the heavens. He will then fly in and get this damsil off the tracks.