I own a 1997 Sebring LXi (2.5L V6 - Automatic) and have been experiencing the notorious "Limp Mode" phenomenon for about a month now. I can't and won't say that it's not my fault for the mechanical issues; I'm a hard driver sometimes. So, for the last month I have been doing a LOT of forum-reading and research on the subject and it seems as if there are a lot of unanswered questions regarding the subject. I have seen proposed solutions along the lines of replacing sensors to an article in the UK of how 'bad fuel' is, purportedly, a likely culprit (fuel burning at a higher than normal temperature causing the O2 sensor to malfunction, etc) to the most obvious of all solutions: Rebuild or replace. Now, before I go any farther, it would be wise of me to give a little background on how this whole ordeal came to be.
It was, as I said, about a month ago. I have been in Limp Mode ever since that time. I noticed it on my drive to work one morning. I was on the highway, going about 55 to 60 mph when I happened to notice my engine spewing out a higher-than-normal RPM. When I looked at the tach, it was reading somewhere in the 4500 range which is unusually high considering I should be in 3rd or 4th gear at about 2500 RPM. As it turned out, I was in 2nd gear even though the gear selector was in D. So I pulled off onto an airport road to try and "figure out" what could be happening before going in to work. During my little test run, I turned the engine off, waited a few seconds, then turned it back on again. Things seemed to be working normally for a few seconds. I accelerated through 2nd gear, and just when I expected it to shift to 3rd, slippage occurred then it defaulted to 2nd gear again. "Great," I thought. So I finished my drive to work in what I would later learn is "Limp Mode". Since that time I have taken it to Auto Zone and had them scan whatever it was that they scanned. I can only assume, based on what I have read, that they scanned the PCM and not the TCM. I don't know if Auto Zone or any other parts store has a DRB II or whatever the dealer uses to scan the TCM with. Regardless, they were able to pull two codes, one of which I cannot remember for the life of me. The other, which I'll never forget due to the nature of what it implies, is Code 53 - Gear Ratio Fault in Gear 3. "Makes sense," I thought. How could the transmission possibly shift into a gear that is sending an incorrect ratio? Again, it seemed to make sense. Based on what I've been reading, I decided to replace both the Input and Output Speed Sensors, and, as many of you have no doubt already guessed- No change. I then decided to take it in to the Chrysler dealer and have them scan it (the TCM, I assume) with the DRB. They came back with two codes:
Code 36 - Fault Immediately After Shift Code 53 - Gear Ratio Fault in Gear 3
And, of course, the service advisor says to me, "You need a new transmission!" Right! What the hell was I thinking?! Because, you know, let me just pull one of those out of my ass here... So I asked how much that would cost and just before I gagged on my own tongue he spouted something like $3,700. Obviously out of the question. Time to rewind the story...
The day before I noticed Limp Mode:
The car was performing just as it should be. All shifting was normal, no concerns. I was thinking about taking a trip down to Minneapolis that afternoon. I decided against that and just drove it around for a bit. It was mostly interstate driving with cruise engaged. I can't be 100% sure, but I want to say that I noticed something funny about it toward the end of my drive that afternoon but because it was so long ago, I can't be sure. Before I parked it for the night I fueled it up. And that's the part that I'm getting caught up on. If that article in the UK that talked about "Bad Fuel" or "Bad Gas" or whatever it said, is correct, and if NOBODY has had luck with the usual suggestions (replace speed sensors, TCM, harnesses, etc), would it be a completely crazy idea to try and have the O2 sensor replaced? I'm just throwing a suggestion out there. Another suggestion that apparently actually worked for someone is the replacement of the "3 grouped relays on the firewall by the brake fluid reservoir".
notlikeme75 posts:
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check out my experience on my 97 avenger in limp mode at http://www.dodgeforums.com . transmission is prob fine. i just replaced the 3 relays that are grouped together on the firewall right by the brake fluid resevoir. the numbers on tops read 83159. good luck.
this was after i replaced input / output sensors and TPS (throttle position sensor)
Beyond that, I'm out of ideas and becoming ever more exhausted doing all this research. It's like a wild goose-chase for a needle in a haystack that doesn't even exist. I just don't want to put more money into this beast than I have to.
One thing I forgot to mention is that this transmission was installed as new when the engine was about 29,000 miles old. So this transmission is about 30,000 miles younger than my engine (engine = 105,000 miles). The previous transmission's gears literally fried in the gearbox causing a rancid stench to linger when I drove it. When I noticed that, the car was parked immediately! It was quite obvious that the transmission was "fried" due to the stench, but quite peculiar that Limp Mode did not engage. Peculiar indeed.
If anyone has any suggestions, ideas, comments or otherwise, feel free to let me know. To me, it honestly feels like there's something else going on here that I'm overlooking. I'm having a hard time believing that this car was just fine the day before and then *BLAM!* Limp Mode. Or 3rd gear is fried. Or whatever the dealer wants to tell me. You get the gist. Anyway, if you made it this far, thanks for reading my novel and I hope to hear some feedback.
36...fault immediatley after a shift ...was added specifically by Chrysler to sniff out hydraulic failures. It means your clutches are having a hard time controlling the gears in the trans under power.
The odds are ...the dealer is not far off on the diagnosis...The price seems excessive since reman units go for under a grand.
If you want to try out the hydraulic unit by itself...just unbolt the solenoid pack on the front of the trans...and see if it slips. That eliminates everything on the outside of the trans.
Thanks for the reply! I will give your suggestion a try sometime this weekend when I get a chance. I am a little unclear, however, as to what I should be looking for when I unbolt the solenoid pack. When you said, "see if it slips", do you mean if it slips in ALL the gears? To clarify my question, if it slips as in won't even go into 1st? Just want to make sure I understand what to expect. Once again, thanks and I'll keep you posted on this when I get to it.
First of all, Let me change the terminology...I should have said UNPLUG not unbolt the solenoid pack hanging on the front of the trans. It is about the sixze of a brick and has an 8 pin connector that must be unscrewed with an 8 mm or 5/16th socket.
Once you have unplugged the 1x2 inch connector...your trans will shift back and forth from rev. to second.
If Reverse does not allow slippage and the tach holds steady at around 2000 rpm when you power brake it with one third throttle. Do the same thing in a forward gear selection.
If the rpm stabilizes at around 2000 rpm in reverse then the reverse clutch and Low reverse holding brake are good and if the forward gear affords no slippage then the Underdrive and 2/4 holding brake are good. Plug your solenoid pack in and go for a drive if third gear will hold without slipping then the overdrive clutch is good and you can be fairly certain it is not worn clutches.
Just a little FYI, a friend of mine is a certified Chrysler technician and he has seen several instances where an A604 has been rebuilt by the dealership only to come back with the same problem. The deciding factor on whether or not the A604 'needed' to be rebuilt when the transmission was brought back, was if a certain solenoid [Chryslers dirty little secret] had gone bad due to dirt contamination, thus resulting in Limp Mode. In situations where the A604 was rebuilt, if the mechanic was not told to replace that solenoid by the manager, then it did not get replaced.
He actually asked the customer if he would rather trust him and let him try something [replacing the solenoid instead of rebuilding the A604] and pay for it instead of him tearing the transmission apart. Needless to say, when the guy got his Sebring back and recieved his bill, he made my friend his personal mechanic, sans Chrysler.
Just to keep you up to date, I did not get a chance to work on the transmission this weekend. Hopefully I'll be able to find time this week for it. Either way, I'll keep you posted.
Shiano,
Thanks for the insight on this issue. Indeed it is peculiar that transmissions have been rebuilt only to come back to the same issue! Along with Bob's idea, I think I'm going to look into the solenoid a little further and see what I come up with.
Ok, lets get something straight. conspiracies don't keep cars from getting fixed, However a thorough investigation of how the car acts backed up by an indepth understanding of the trans design does.
Shi, come on, Chrysler's dirtly little secret??? If there was merit to that it would be a class action lawsuit and lots of attorneys would be tanning thier daughters with that money.
but just in case...where is the solenoid your buddy touted?
Ok, lets get something straight. conspiracies don't keep cars from getting fixed, However a thorough investigation of how the car acts backed up by an indepth understanding of the trans design does fix cars...was what I meant to say.
well, first, the Chrysler dealership where i live has never been trustable because of the managing of it.
I wouldn't put it past the management to say that the head mechanic found i had a bad flux capacitor.
"Dirty Little Secret" yes it is. And no there aren't [viable lawsuits]. Thats b/c of the papers you sign. But no. that little solenoid you were talking about is in a location that is easy to get dirty and unless you have good understanding of the A604 [since it has it's own computer] that solenoid isn't on the top of the list of things you think of. It's never suggested by Chrysler to change that, it's always 'New Transmission' or 'Rebuilt Transmission'. That's why its a secret.
And this is straight from the Certified Chrysler Mechanic. He's a real person, not just a robot that punches a timeclock. He knows how hard it was to make money before he became a Certified Mechanic with Chrysler, GM, and Ford.
I hate Mustangs, but you should see his 302 Foxbody. VERY nice. He did all the work.
The solenoid pack on the front of the F4AC1 trans consists of 4 solenoids and three pressure switches. It is powered by a permanently grounded relay that the TCM shoots power to at key on.
These solenoids control 4 clutches, the underdrive, 2/4, low/rev, and Overdrive. There is no solenoid for the reverse input clutches since they are controlled directly by the manual valve hooked to the shift linkage. In addition, due to valving in the valve body, the L/r, and 2/4 solenoids do double duty...for example the L/r is also the lock up solenoid for the tcc when you are in second, third, or 4th gear.
The TCM runs the solenoids directly and there are no shift valves to cushion the shifts...only accumulators. and the learned value (I gave the forum in another discussion in transmissions forum) control the shift quality .
The thing that sets this Mopar exclusive and worldwide industry first design apart from everything else on the planet is that it can accomodate wear in the clutch packs by changing the duty cycle as the TCM evaluates the speed sensors input.
Now, to answer the question for all. The solenoids have two ports..inlet and outlet, both of which have small plastic drop in filters (screens). If there are pieces of clutch debris in a filter and it is bad enough to impede the solenoids ...you might be able to forestall the inevitable and empty them and make the trans shift again....but how long will it last? If your buddy is in a chrysler facility that is recommending the hydraulic unit needs rebuilt because they found clutch material in the solenoid pack...BE VERY GLAD. They are thorough and will build a trans that is up to your modifications.
I will say that 90% of the folks that are modifying cars look at it in this simplistic way....what is the least work I have to do to get the trans to shift today.
Now they may have a 3.0l swapped in with upgraded heads, udp, headers, crank scraper, nitrous shot. etc. but it is all running through a bone stock trans that was band aided by fixing "Chryslers' dirtly little secret" and not changing anything on the trans.. lol clock is ticking for the meltdown.
The impressive vote of confidence is ...the oem trans must be able to stand up to all this if this forum is any indication.
My suggestion to the original thread is sound info. but be forewarned...it may only uncover the actual problem and cast clarity on what and how much it will cost to FIXITFIRSTIME.
I agree shi, take the chip off your shoulder and go into Joe Friday mode, stick to the facts , read my write up with an open mind. You will see I am telling you chapter and verse about the exact part you are trying to cast shadows on. There is no mystery here.
If you clean it and put it back on after finding junk in it without finding the root cause...you are asking for trouble. The dealer that is trying to be thorough is not part of a conspiracy. Print this and show it to your buddy.
Sorry, i came off wrong on that [i probably left something out]. What i meant to say was he actually was TOLD not to replace it by the higher ups at the dealership on the transmission the first couple of times it was rebuilt [and yes this one was serviced 3 times total]. On the third time they never told him directly to replace that. So he went to the customer and asked them if they would like to try something different. He had noticed that when that was the problem, rarely was it suggested to be replaced. The one he worked at wasn't a 'Here's the problem, fix it' type dealership. It was more like 'Do this because the head mechanic thinks its the problem.' lol
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