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Drives by Braille
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Discussion Starter · #1 ·
Ok - driving home after work today my check engine light came on, so I turned around and went over to AutoZone to have a friend check it out. The code that came up was a "P0740", wrote it down and went home to research, because the little reader they have doesn't say anything. So, looking it up on the net I found out this:

P0740: Relationship between engine and vehicle speeds indicated failure of torque convertor clutch lock-up system (TCC/PTU solenoid)
Durring my drive home I didn't notice any slipping or hesitation, or any other funny feelings. Parked it and decided to check the trans fluid. Its just under the hash marks on the dip stick so I'll add some tomorrow(all out here at home). So do you think that just being low on fluid caused this? Or is it something that I should take to a mechanic? Because I'm no tranny expert.
 

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Ok - driving home after work today my check engine light came on, so I turned around and went over to AutoZone to have a friend check it out. The code that came up was a "P0740", wrote it down and went home to research, because the little reader they have doesn't say anything. So, looking it up on the net I found out this:



Durring my drive home I didn't notice any slipping or hesitation, or any other funny feelings. Parked it and decided to check the trans fluid. Its just under the hash marks on the dip stick so I'll add some tomorrow(all out here at home). So do you think that just being low on fluid caused this? Or is it something that I should take to a mechanic? Because I'm no tranny expert.

its hard to tell. the TCLU merely locks the input compressor and the output turbine in the torque converter together so you get a real 1:1 drive ration going into the tranny (torque converters without a lockup do slip some and you actually have some gear reduction before the tranny).

it could be low fluid, but the solenoid might have gone bad. fill up the tranny, erase the code, reset the computer and see if it comes back. start simple and then worry about the more difficult / complicated / expensive stuff ...

if the light comes back on, or you notice sliping at higher speeds, then have it looked at by a professional.
 

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Drives by Braille
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13,642 Posts
Discussion Starter · #3 ·
Today durring lunch I added a little over half a quart of ATF at AutoZOne and had them rescan and then erase the code. Driving it for most of the day and the light has stayed off. I've started and stopped it maybe half a dozen times since. SO I htink I might have been a little too low on tranny fluid and it noticed it? Jeep seems to be running just as it always has so hopefully that took care of it.
 

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To get an accurate reading you need to be fully warmed up and idleing in Neutral. These auto trannies dont pump fluid in PARK (Unless modified :D ) so you will get a higher than normal reading in Park.

Joe
www.absoluteoffroadphx.com
 

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Drives by Braille
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13,642 Posts
Discussion Starter · #5 ·
Yeah - I did check it in neutral and after a good warm up drive... its about 3/4 the way up the safe zone now.
 
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