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Check engine light: P0740 Transmission problem?

05-15-2008, 04:30 PM
I just bought a 2001 Chrysler 300M because my wife and I love the way it road. Unfortunately less than a week after buying it the check engine light comes on. I read the DTC and come up with P0740 and P0700 which implies a transmission problem. It shifts fine which was confusing. I check the transmission fluid. It looks OK but the level is up to full on HOT when the transmission should be warm (or cool). Which makes me believe the dealer topped the fluid level off but overfilled it.

Could that cause the P0740? If so, short of dropping the pan, is there anyway to remove the excess fluid. I have never overfilled a transmission level, of course I prefer manual transmissions, so my experience is limited. I expected a timing belt repair bill when I bought the car, not a transmission problem. :confused:

05-15-2008, 09:39 PM
Hi, I am an automatic transmission engineer at Chrysler and a P0740 fault means the torque converter lock-up clutch is slipping. This is not related to oil level but to answer that question first, a tube can be inserted into the fill tube and draw approximately 1 pint of fluid out and check it again. An overfilled transmission can only cause a problem if the transmission is extremely hot and you are going above 80 mph. Foam will develop and oil will expul from the vent. Not likely your issue. At 70 - 90 deg, the fluid should be in the warm range.

Now, your fault can be caused by the following issues in the following order of most likely first: 1) Debris in the valve body causing the torque converter control valve to be sticking. 2) Worn oil pump bushing. 3) Failed torque converter lock-up clutch. Any one of these can cause the fault. Now the fault will not cause the transmission to go into limp-home mode (2nd gear only). The only thing that will happen is you won't have the torque converter clutch engage (loss in fuel economy). The transmission controller will attempt to engage the torque converter clutch each time the ignition key is recycled. I would drive the car up to 50 mph and let up on the accelerator and see if lock-up occurs. Then slowly increase the throttle and see if the engine speed rises without vehicle speed increasing. If so, then the clutch is slipping and the fault will reset. The only way to fix it is to install a pressure gauge on the lock-up on port and measure the pressure when lock-up is scheduled by the transmission controller. Unfortunately, this is not so easy to describe unless you are a transmission mechanic. :frown: Nothing is easy to fix this problem unless the problem was caused by debris in the valve body and the debris flushes itself out and the problem goes away. This is likely so keep driving it and see if it fixes itself.:runaround:

05-17-2008, 11:46 AM
Did you buy this from a dealer? If so I would be camping on their doorstep and make them take care of this problem, not you. I understand if it didn't come with a warranty or if you bought it as is from a private party. Just another thought.

05-17-2008, 12:01 PM

05-18-2008, 02:30 PM
Thanks for your help. I bought the car "as is" although I could have added a "warranty". I thought about buying the warranty BUT you have to have a failure for it to be covered. Although any USED car is traded for some reason, this car looked like it was well maintained. The extra fluid upset me but I only noticed it after the P0740 code popped up :shakehead. Since I accepted the fact that I would need to replace the timing belt in the very near future, I decided a full transmission flush might be another good investment; fix the fluid level problem and hopefully any dirt that might have produce the P0740 code. Neither my wife or I have noticed any "transmission shift problems". So we will drive it and see if the original owner dumped the car because he was worried about a transmission bill. SInce my mechanic did not notice anything unusual when he flush it, I hope that everything will be ok.

05-19-2008, 06:06 AM
Good luck. Let us know how it all works out.

07-13-2008, 04:48 PM
It appears that flushing the transmission has fixed my problem. When I first got the car back, the check engine light came on and I assumed it was the same error code but before I had a chance to read it the light went off and has stayed off. Hopefully just a little dirt. Certainly I never felt any problems with the shifting but?? On to my next problem: where to buy a compatible antifreeze. I can not believe what I am reading about this.

07-14-2008, 08:02 AM
The proper anti-freeze IS important. GO-5 is the only type. Accept no substitutes! I have gotten it at Autozone. Try any of the parts stores. Do not let anyone, including the dealer, tell you that you can use anything else. I know for a fact the dealers have installed the wrong anti-freeze more than once. I have two quarts of Zerex GO-5 sitting in my garage in case I need it.

08-23-2008, 09:16 AM
I am afraid my transmission problems came back big time. We have been driving for 3 months, no check engine light, no shifting problems; everything looked OK. I went ahead and had the timing belt and water pump replaced (~76K miles but 7years) and the coolant system flused. Ready for the road.
My wife called yesterday and said she heard a high pitched noise and thought the transmission was slipping. Although the check engine light had not come on, she decided to wait until I came and looked at it. I got there, did not hear anything and decided to drive it home. About 15 miles down the road I started to hear the noise and pulled over to check it out. No check engine light. Since the noise varied with the engine and it was in park and neutral I assumed it was an alternator, etc. and continued down the road; mistake. About 3 miles further I notice the tach moving up but the speedometer steady, implying that the transmission was slipping. Not long after the check engine light did come on. At this time the whining noise was quite loud. Stopped the engine for about 10 minutes, and continued down the two lane, narrow road to home. Bottom line is that I stopped two more times when the transmission slipped into second gear with the noise becoming louder. Trip of 30 miles took about 1 hour but I made it home. Checking my transmission flush receipt I noticed ATF BULK DEX 3. Since I thought it was suppose to be ATF4, I called the shop and asked what fluid they listed for it. They said ATF 3 or 4 depending on the owners manual. I asked why did they put in Dex 3. The person I talked took could not believe me and checked his records. After calling back a new person said the pump went out, I asked again about the Dex 3 and he said they did not think it would be a problem but would consult with their Chrylser transmission expert. Sounds like I am going to get the run around. Recommendation? Is it time to trust my Chrylser dealer? I like the car but am scared of the maintenance / finding a good Chrysler mechanic.

08-25-2008, 07:55 AM
ATF4 is the only way to go. Period. They owe you repairs. I am not a transmission expert, but they were wrong.

09-02-2008, 09:59 PM
Good luck. Let us know how it all works out.
I have a similar problem but I threw a rod and replaced the engine with a rebuilt one, then my check engine light came on. Took to trans shop and replaced the sol pack and now the default sticks at about 50mph again. two codes pop again 1776 &1784. I was told that the Trans on these cars are horrible and this will be constant. 141k mi on the car.

09-03-2008, 07:09 AM
I have a similar problem but I threw a rod and replaced the engine with a rebuilt one, then my check engine light came on. Took to trans shop and replaced the sol pack and now the default sticks at about 50mph again. two codes pop again 1776 &1784. I was told that the Trans on these cars are horrible and this will be constant. 141k mi on the car.

I wouldn't say the trannys are horrible. The only major problems I have read about are the input and output sensors going bad on a "regular" basis. Your codes suggest a different problem, such as:

"1776 Chrysler Solenoid Switch Valve Latched in LR Position (this is a transmission issue which may involve replacing the valve body and solenoid pack; on some models there is a TSB on this problem so be firm with your dealer / Chrysler)." or, there is

P1776 Ignition Retard Request Duration Fault

along with:

P1784 Transmission Mechanical Failure - First And Reverse

It just depends on which company's code you are reading.

11-03-2014, 07:28 PM
Hey all,
I'm new to this site but have used it a few times and am going to reopen this thread.
I bought a 2002 Chrysler 300m 1 year ago when it had 90k. The car now has 100k miles. Check engine light came on about 5 months ago. Pulled the codes and continues to show P0700, P0740 after a few resets.

The problem I notice is when braking/deceleraring to a stop. It seems that the transmission gets confused downshifting. Rpms rise then fall. When in park, blow fans cycle on and off every 8-10 seconds. I have got in the habit of just putting it in neutral when coming to a stop.

Delema: I live in CO and got a bit of hail damage (doesn't look bad at all). Insurance is offering to buy the car from me. After wheeling and dealing their offer is $1000 higher than what I bought the car for last year (or I can keep the car and they will give $2000 less)

I really like this car and have been driving it with the CEL on for 5 months and the slowing down issue has not got worse.

Anyone else have this same issue? If so, what was wrong and did you fix it.
Should I look into fixing it or ditch the car and look for something else?!

I have done lots of research on the P codes but could it be a simple fix? My battery is testing a little low on the voltage meter.

05-27-2015, 08:48 PM
When I had that same problem with my 05 Chrysler pacifica touring with it lunging forward the problem was the alternator. It has a bad diode in it. Once I replaced it that problem stopped.

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