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P0740

 
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Old 10 Jun 2017, 12:37 pm
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Location: Naples Fl
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Default P0740

My 2006 limited edition with turbo check engine light came on and I got the code P0740 on my meter. I had the timing belt replaced about a month ago (96,000 miles) and since he had to go deep I had the passenger side motor mounts replaced as well as the water pump. I also had it tuned up at the time (wires and plugs). It is running great, but I got this light. According to the book it is a torque converter clutch solenoid circuit problem. I am wondering (hoping) if there might not be a bad ground somewhere generating a little extra resistance causing this. The solenoid function is obviously working. Any ideas? My wife won't stop complaining about the light. My first step is to cancel it and see how long it takes to come back on.

Thanks
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Old 10 Jun 2017, 01:04 pm
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Location: Thousand Oaks, CA
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Default Re: P0740

P0740-Torque Coverter Clutch, No Rpm Drop at Lockup

Possible causes:

1. Fused Ignition Switch Output Circuit open
2. Intermittent Torque Converter Clutch Solenoid
3. TCC Operation
4. Torque Converter Assembly or TCC Solenoid Stuck
5. Tranmission Fluid Level and Condition
6. Vehicle Configuration non-standard
7. TCC Solenoid

I would first suggest checking the level and quality of the transmission oil. When was the transmission oil changed last?
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Old 10 Jun 2017, 06:51 pm
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Default Re: P0740

Thanks,

I will check the fluid. I don't think it is any of the other things because the transmission shifts fine and does not slip. What exactly does the solenoid do? Does it power a hydraulic valve in the transmission to engage or disengage the clutch or is it mechanical. Also, I would assume that the solenoid is normally open and in that state the clutch/ tranny is disengaged. Is that correct?

Also perhaps the solenoid, even though it is working fine, is drawing too much or too little current indicating an impending failure. Since the message is solenoid circuit fault, I would assume its voltage, resistance, or current is outside the threshold parameters. I guess dirty fluid could cause the solenoid to draw more juice and perhaps low or aeriated fluid could cause it to draw too little.

I will keep you posted.
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Old 10 Jun 2017, 07:37 pm
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Default Re: P0740

Quote:
Originally Posted by PTRick View Post
Thanks,

I will check the fluid. I don't think it is any of the other things because the transmission shifts fine and does not slip. What exactly does the solenoid do? Does it power a hydraulic valve in the transmission to engage or disengage the clutch or is it mechanical. Also, I would assume that the solenoid is normally open and in that state the clutch/ tranny is disengaged. Is that correct?

Also perhaps the solenoid, even though it is working fine, is drawing too much or too little current indicating an impending failure. Since the message is solenoid circuit fault, I would assume its voltage, resistance, or current is outside the threshold parameters. I guess dirty fluid could cause the solenoid to draw more juice and perhaps low or aeriated fluid could cause it to draw too little.

I will keep you posted.
P0740 can be triggered by one of the listed two below:

A. Transmission must be in EMCC, with input speed greater than 1750 RPM.
TCC/L-R solenoid achieves the maximum duty cycle & canít pull engine RPM within 60 RPM of input speed.

B.Transmissions is in FEMCC & engine slips TCC greater than 100 RPM for 10 seconds.

I would suggest checking the transmission oil filter.

You might want to take it to a transmission shop that can tell you the most common problem that P0740 triggers for the transmission you have.
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Old 22 Jun 2017, 10:15 am
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Default Re: P0740

The light went out on its own. It has been off for 12 days now and my wife has been driving every day, mostly on streets, but sometimes on hwy up to 80 MPH. I am inclined to let it go unless the light comes on again because there is no noticeable evidence of transmission slippage.

In a couple of weeks I will check for a code if the light does not come back on. The light seems to be working as it comes on when the key is turned on before the car is started. I am using an Innovia 3160 scan tool.

Initially I tried the 3 consecutive turn the key on-off trick but was unable to make it work. I rotated the key out of the lock position and then 3 times to the on and back to the out of lock but got nothing so I used the scan tool. Did I do the "trick" correctly?

Thanks for your help.
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Old 22 Jun 2017, 10:43 am
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Default Re: P0740

Quote:
Originally Posted by PTRick View Post
The light went out on its own. It has been off for 12 days now and my wife has been driving every day, mostly on streets, but sometimes on hwy up to 80 MPH. I am inclined to let it go unless the light comes on again because there is no noticeable evidence of transmission slippage.

In a couple of weeks I will check for a code if the light does not come back on. The light seems to be working as it comes on when the key is turned on before the car is started. I am using an Innovia 3160 scan tool.

Initially I tried the 3 consecutive turn the key on-off trick but was unable to make it work. I rotated the key out of the lock position and then 3 times to the on and back to the out of lock but got nothing so I used the scan tool. Did I do the "trick" correctly?

Thanks for your help.
Your OBD scan tool is much more accurate than the "key dance" is. Since you have no errors, IMO, leave it alone until it, or another code appears.

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