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HELP! 1997 XJ diagnostic code 45-OVERDRIVE SOLENOID - FIXED

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Mad Scotsman
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Joined: 08 Jun 2007
Location: Golden, Colorado

PostPosted: Fri Jun 08, 2007 11:15 am    Post subject: HELP! 1997 XJ diagnostic code 45-OVERDRIVE SOLENOID - FIXED Reply with quote

I have a 1997 Jeep Cherokee 4WD. I keep getting a diagnostic code 45 (overdrive solenoid has an open or short) but transmission shifts fine through all 4 gears...DOES NOT go in to "limp mode". Tranny is AW4 (automatic obviously). I'm thinking there may be an electrical glitch firing off this code causing check engine light to come on. Ideas? Check engine light is driving me NUTZ! HELP!!

Oh, BTW.... yes, I have checked the tranny fluid level/condition. All seems fine there. Checked t-case and all seems fine there. Vehicle seems to shift fine in to all 4 gears. I can reset the dummy light & drive the vehicle around for a while, highway & surface streets. The problem seems to arise after one or two start cycles. You can be cruising along and the check engine light comes on. It will spit a code 45 out indicating a problem with the OD solenoid. I just unhooked the battery again and pulled all the electrical connections apart under the hood including those to the computer, the bulkhead connector, and transmission sensors. I also disconnected the sensor to the t-case. I cleaned them with electrical contact cleaner & just put them back together. I also changed out the negative battery terminal connector with a brand new connector as the old one was suspect. Additionally, I disconnected the ground to the inner fender as well and I sanded the wire & connection point to ensure good ground. I have not tested the results yet as I stink and need a shower! LOL! It's hot here today in Texas!

UPDATE: Ok, upon closer inspection it would seem I am not getting torque convertor lock-up in overdrive once the vehicle is up to operating temperatures. It seems to take 20-30 minutes before I get the "check engine" light. It seem that the tranny is shifting 1-2-3-4 but then there is no drop in RPMs in 4th gear when the lock-up is supposed to occur. Is this indicative of a malfunctioning overdrive solenoid? If so, where the hell do I get one? Is this a dealer only part? Can someone direct me to a source on the net?


Last edited by Mad Scotsman on Mon Jun 11, 2007 11:56 am; edited 1 time in total
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Mad Scotsman
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PostPosted: Sat Jun 09, 2007 3:22 pm    Post subject: Reply with quote

Nobody got any love for the new guy?

Well, I went to Vato Zone and pulled codes.... this is what I got.

P0700 & P0743... both related to a fault signal to the PCM courtesy of the transmission. The million dollar question is this really a faulty solenoid, a bad connection somewhere, or perhaps a bad TCM? Is there even a seperate TCM on a 97 Cherokee or was it integrated in to the PCM? I want this damn thing fixed post haste!
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ThePhantum
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PostPosted: Sat Jun 09, 2007 3:44 pm    Post subject: Reply with quote

To my knowledge, there isn't a separate TCM on the 1997...it's integrated into the ECM.

Since the 743 code indicates an electrical fault in the torque converter clutch solenoid circuit, I would check those connections, test the solenoid (if possible...the FSM would dictate the procedure if there is one) and replace it if necessary.
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Mad Scotsman
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Joined: 08 Jun 2007
Location: Golden, Colorado

PostPosted: Sat Jun 09, 2007 6:16 pm    Post subject: Reply with quote

ThePhantum wrote:
To my knowledge, there isn't a separate TCM on the 1997...it's integrated into the ECM.

Since the 743 code indicates an electrical fault in the torque converter clutch solenoid circuit, I would check those connections, test the solenoid (if possible...the FSM would dictate the procedure if there is one) and replace it if necessary.


Thanks for feedback bro! I was wondering about the TCM on a 97.... seems I read somewhere that they were intergrated in to the ECM.... guess I was right on that one. Besides I looked under the passenger dash and couldn't find one! LOL!

I really was hoping I'd find a cruddy or loose connector. I'm really not wanting to pull the trans pan but it's looking more like that's the only option left at this point. That's the only way to verify the resistance on the tranny solenoids. I believe they are supposed to be 11-15 ohms if I'm correct. I guess I'll go ahead and yank the pan to check those. The only concern I have about checking the solenoids like this is the fact this problem (check engine light & codes) only seems to manifest itself after the vehicle is up to operating temperature for 20 or so minutes. This would seem to indicate a voltage drop induced by increased resistance. This increased resistance, in turn, is most likely being caused by heat. I suspect this is triggering a drop in voltage in the TCC solenoid and therefore tripping the codes I am getting. So, I am wondering if there is another problem (not tripping a code off) that is inducing excess heat in the tranny causing the codes I am getting? I know that most likely I just have a bad solenoid BUT I also wonder if the solenoid issue is just a symptom of another problem. I do not get any indications that the vehicle is running hot but then again what if the temp sending unit is faulty? Maybe I'm over-thinking this one but I want to fix this once and not buy a bunch of crap I don't need to replace. Any chance this could be related to the TPS as well? Just thinking out loud on the possibilities...

... and now for the million dollar question; WHERE CAN I GET THESE SOLENOIDS FOR THE TRANS? There doesn't seem to be a huge availability for these parts from what I can tell. Any information on that would be greatly appreciated i.e. part numbers, manufacturers, sources, etc.

Thanks again!
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Jpreverso
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PostPosted: Sun Jun 10, 2007 7:12 am    Post subject: Reply with quote

If you havent already opened up the tranny looking for the TCM the manual I have access to says its located under the instrument pannel (cluster) on the drivers side. when you turn your ignition on, off, on, off, on with in 5 sec. (not all the way to start) what codes does your check engine light flash to you. I assume you have disconected yor battery recently so it should flash a 12 first. The auto Zone Code 0743 will = 37 , the other code you got from the zone, 0700 I dont have a translation for. I might be getting a head of my self but 0743 code would be for a right hand drive cherokee. If thats the case the TCM will be located behind the instrument panel.

Last edited by Jpreverso on Sun Jun 10, 2007 8:58 am; edited 1 time in total
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Mad Scotsman
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PostPosted: Sun Jun 10, 2007 8:12 am    Post subject: Reply with quote

Jpreverso wrote:
If you havent already opened up the tranny looking for the TCM the manual I have access to says its located under the instrument pannel (cluster) on the drivers side. When it come to the tranny I get lost, but if there is any thing I can look up for you let me know.


No, I haven't opened the tranny YET! LOL! I seem to be finding conflicting information about the TCU being integrated with the ECU. I am sure I have read both that it was integrated with the ECU and that it is a seperate module. I am going to go with the "seperate module" theory at this point since I can test the tranny solenoid resistance if I can only locate the TCU and its connector. Otherwise, I have to pull the tranny pan to test the solenoids. Obviously I don't want to do that if I don't have to. Besides, it seems to be a lost cause finding any suppliers online for the solenoids. I sure hope my local NAPA can get them!?!?!

Anyway, thank you very much for the information on the TCU. Very Happy I'm going to go look for it now!
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Mad Scotsman
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PostPosted: Sun Jun 10, 2007 8:25 am    Post subject: Reply with quote

Jpreverso wrote:
If you havent already opened up the tranny looking for the TCM the manual I have access to says its located under the instrument pannel (cluster) on the drivers side. When it come to the tranny I get lost, but if there is any thing I can look up for you let me know.


Hey man, thanks! You are right! The TCU is under the instrument cluster.... went out there and poked my head under the driver's side dash and there it was! Thanks! Now I can test my solenoids without having to pull the pan! rofl
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Jpreverso
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PostPosted: Sun Jun 10, 2007 9:45 am    Post subject: Reply with quote

If the solenoids all test okay let me know, I think i was typing at the same time you were I added on to my first post, If your jeep is a left hand drive that code 0743 might not be correct acording to the manual i have.
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Mad Scotsman
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PostPosted: Sun Jun 10, 2007 10:14 am    Post subject: Reply with quote

Jpreverso wrote:
If the solenoids all test okay let me know, I think i was typing at the same time you were I added on to my first post, If your jeep is a left hand drive that code 0743 might not be correct acording to the manual i have.


Yes, my Jeep is left-hand drive. The solenoids all testing within range while cold (11-15 ohms). I need to do a "hot test" at operating temps to see if one of the solenoids develops a significantly higher resistance. If so, then I think I have my answer.

UPDATE: Ok, I got the engine/tranny up to operating temps and it would seem that my TCC solenoid is developing significantly higher resistance at operating temps. It reads normal when cold (11 ohms) but shoots way up when hot (150 ohms). The other two solenoids registered within range at operating temps. So, if I am interpreting the results correctly I seem to have a TCC solenoid failing at operating temps. What does everybody think?
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Jpreverso
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PostPosted: Sun Jun 10, 2007 1:14 pm    Post subject: Reply with quote

when you did the resistance tests did you disconect one of the battery wires? Im not understanding how a solenoid could gain that much restiance through heat. Is it possaible that there is some kind of temp switch that closes to feed somthing else on the same circuit . when the truck reaches normal opp. temp, Or is that a common way for a soleinod to go. I would it would short out. But like I said I dont understand how the trany works.
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Mad Scotsman
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PostPosted: Sun Jun 10, 2007 2:04 pm    Post subject: Reply with quote

Jpreverso wrote:
when you did the resistance tests did you disconect one of the battery wires? Im not understanding how a solenoid could gain that much restiance through heat. Is it possaible that there is some kind of temp switch that closes to feed somthing else on the same circuit . when the truck reaches normal opp. temp, Or is that a common way for a soleinod to go. I would it would short out. But like I said I dont understand how the trany works.


Well, I'm not a transmission expert by any means but I do understand basic electronics & DC theory. Basically Ohms Law states that voltage (V) = resistance (R) x amperage (I). So you have the mathematical formula V=R x I. The TCM is expecting to see a certain voltage drop in the TCC circuit. I believe the voltage drop range (I could be off here) for the TCC circuit is .5v - 4.5v. In any case, the voltage drop in the TCC circuit that the TCM would normally expect to see is dependent upon the TCC solenoid resistance being within range (11-15 ohms). If the resistance (R) value is changed in the equation V=R x I then obviously you change your voltage value (V). Since I am seeing a "hot" resistance value in the TCC solenoid of 150+ ohms this is telling me that the solenoid is having a heat related malfunction. Now, as for what is causing this malfunction I can only guess. However, the most likely explanation is that the solenoid is bad. Electrical components do funny things when they break down. Elevated resistance in this case is most likely indicative of a failing electrical component, in this case the solenoid. Excessive heat in an electrical circuit will always result in increased resistance. Failing electrical components will often heat up and thus have an increased resistance in the circuit. Since the "check engine" light does not come on immediately (only after 20-30 minutes of operation) then I have to assume the PCM is receiving an "out of voltage range" indication from the TCM in regards to the solenoid once it gets hot. This would make sense since the increased resistance of the solenoid would most definitely throw the TCC circuit voltage out of range. It would also explain why the torque converter lock-up stops functioning after 20-30 minutes of driving. The funny thing is the TCC solenoid has returned to the "in range" resistance value now that it has had a chance to cool. Again, the most likely explanation is the TCC solenoid is going bad. Having said that it can ALWAYS have an alternate cause. I am simply going with the most likely at this point. Also yes, I did have the battery connected during the test. If the tranny was overheating then I would expect to see the #1 & #2 shift solenoids overheat too and also show an increased resistance value. However, the #1 & #2 shift solenoids exhibited resistance values that were well within specs even when the engine and tranny were up to operating temperatures. The only solenoid that showed an abnormal resistance value at operating temps was the TCC solenoid. There is always a chance the solenoid malfucntion could just be a symptom of a larger issue but I won't know that until I replace the TCC solenoid. However, I am fairly certain a new solenoid will solve my problem. I guess I start my hunt for a new solenoid tomorrow!

Anyway, sorry to be so long-winded here but hopefully this gives you a better insight on how I arrived at my diagnosis. Cheers!
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Mad Scotsman
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PostPosted: Sun Jun 10, 2007 10:49 pm    Post subject: Reply with quote

BTW, found this great document on the web for diagnosing AW4 woes....

http://jeepgarage.free.fr/OWN/auto%20trans%20diagnosis.pdf

Let me know if the link doesn't work for you and I can e-mail the document to you.
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Mad Scotsman
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PostPosted: Mon Jun 11, 2007 12:04 pm    Post subject: Reply with quote

Thought I would just update anyone who is interested. I fixed my problem. It was indeed a faulty TCC lockup solenoid (#3 solenoid). I picked up a new solenoid from a supplier here in Dallas ($105 - OUCH!). I installed it and put in a new tranny filter & pan gasket... filled it with 4 qts. of new fluid. Fired her up, let her get hot, test drove her and she performed flawlessly. I got torque convertor lockup like I am supposed to and it even ran a little cooler. Best part is no more "check engine" light. The ironic part of it all was I kept checking the resistance value of the failing solenoid. It kept coming up with all kinds of erratic resistance readings that seemed to fluctuate with the ambient air temperature (my best guess). I took it with me to the parts house to make sure I got the right part. Well, after riding in my air-conditioned truck it read absolutely normal! I know damn well this solenoid was having out of range resistance readings (and I know how to use a multi-meter!).

So, the important lesson to take from this experience is understand that failing electrical components can sometimes appear normal when they are not under normal operating conditions. They may only fail under operating conditions at operating temperatures. Therefore, always check components under the various conditions (hot vs. cold, etc.) before you deem the part o.k. It may not be o.k. I make no claims at being an expert but someone who is a novice may not have recognized the heat related failure I was experiening. I am a happy camper now!

Happy wrenching!
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dancerman
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PostPosted: Mon Jun 11, 2007 4:19 pm    Post subject: Reply with quote

Hey, thanks for taking the time to document this. I'm sure it will be useful in the future.
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Mad Scotsman
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PostPosted: Mon Jun 11, 2007 5:14 pm    Post subject: Reply with quote

dancerman wrote:
Hey, thanks for taking the time to document this. I'm sure it will be useful in the future.


No problem. I had a hell of a time finding any real specific information on the net when I was trying to troubleshoot this issue. This is the first Jeep I've owned. I just got it like 5 days ago and wouldn't you know it.... check engine light comes on. Well, being totally unfamiliar with Jeeps in particular and being nowhere near an expert on AW4s left me with no choice but to have a crash course in Jeeps and the AW4. Between putting the pieces from the net together and my experience with electronics I felt fairly certain that I had made the correct diagnosis. Apparently the results seem to indicate that I am correct so far! LOL!

Well, I do know that others out there have had this same problem and have probably had a hard time finding the needed information to correctly diagnose the problem. Perhaps the admins will put a sticky on this thread or at the very least add the AW4 Diagnosis Guide to the tech sticky. That link is in one of my previous posts to this thread.

One last note that I'm sure most people are aware of is the fact that many parts for the AW4 and the A340 (Toyota) are interchangeable. They are pretty much the same tranny from what I gather.
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