P0740 torque converter circuit malfunction - JKowners.com : Jeep Wrangler JK Forum
 
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post #1 of 5 Old 11-11-2018, 02:17 PM Thread Starter
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P0740 torque converter circuit malfunction

I have a 2011 jku Sahara 3.8 and at 87k it got a code, p0740 torque converter circuit malfunction. The transmission runs fine, no slipping no shuddering, atf4 is clean and does not run hot. I'm thinking I gotta drop the transmission pan and install a new valve solonoid body. Has anyone else come across this code, this issue? Has anyone replaced a valve body or torque converter? How did you resolve it?
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post #2 of 5 Old 11-11-2018, 04:14 PM
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You should take it to a reputable trans shop to get it diagnosed. No sense in throwing money selonoid pack if it doesn't need it.

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post #3 of 5 Old 11-11-2018, 04:59 PM Thread Starter
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I did, they tried to sell me a new transmission at aamco, took 200$ from me to see if it was my solonoid or tc and instead ignored all that and kept pushing the tranny on me. You don't replace an entire transmission without fixing the first steps to this problem, also no one has ever replaced an entire transmission over this code for this year model jeep, especially if no other codes or symptoms associated with a failing transmission show up. After reading Google reviews it seems that's what they do, I'm not doing that nonsense again. I need to hear from who have had this issue and what they did to resolve it. Are there no mechanics on this forum who have experienced this? I do all my own work on my cars and I've never come across this.
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post #4 of 5 Old 11-11-2018, 05:37 PM
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While waiting for a response from someone who has had this code...

The first thing I would do is install a gauge or programmer that can display torque converter clutch slippage.
I have not had the code, and the slippage when the TC is locked hovers around zero.


Here is some information regarding the code you have.

P0740-TCC OUT OF RANGE

Theory of Operation

When in 2nd, 3rd, or 4th gear, the Torque Converter Clutch (TCC) can be locked or partially locked when certain conditions are met. The TCC piston is electronically modulated by increasing the duty cycle of the LR/TCC solenoid until the torque converter slip difference (difference between engine and turbine speed) is within 60 rpm. Then the LR/TCC solenoid is fully energized (FEMCC / 100% duty cycle). Torque converter slip is monitored in FEMCC to ensure adequate clutch capacity. The transmission will attempt normal EMCC operation (not in limp-in) even after the MIL is illuminated. MIL will illuminate after 5 minutes of accumulated slip in FEMCC.


When Monitored:
The Torque Converter Clutch (TCC) is in FEMCC or PEMCC, Transmission temperature is hot, Engine temperature is greater than 38 C or 100 F, Transmission Input Speed greater than engine speed, TPS less than 30, and brake not applied.

Set Condition:
The TCC is modulated by controlling the duty cycle of the L/R Solenoid until the difference between the Engine rpm and the Transmission Input Speed rpm or duty cycle is within a desired range. The DTC is set after the period of 10 seconds and 3 occurrences of either: FEMCC - with slip greater than 100 rpm or PEMCC - duty cycle greater than 85%.

Possible Causes
RELATED L/R SOLENOID OR PRESSURE SWITCH DTCS PRESENT
INTERNAL TRANSMISSION

2008 Unlimited Rubicon Automatic
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post #5 of 5 Old 11-11-2018, 06:01 PM
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Quote:
Originally Posted by Jaguarzero View Post
I did, they tried to sell me a new transmission at aamco, took 200$ from me to see if it was my solonoid or tc and instead ignored all that and kept pushing the tranny on me. You don't replace an entire transmission without fixing the first steps to this problem, also no one has ever replaced an entire transmission over this code for this year model jeep, especially if no other codes or symptoms associated with a failing transmission show up. After reading Google reviews it seems that's what they do, I'm not doing that nonsense again. I need to hear from who have had this issue and what they did to resolve it. Are there no mechanics on this forum who have experienced this? I do all my own work on my cars and I've never come across this.
I too do my own repairs, but to do a correct diagnosis on this you will need a scanner. Go to an independent trans shop or a reputable garage that will look into the code for you. I've worked in the transmission business and to say to you just throw in a selonoid module in it is not going to help you.

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