2000 Dodge Caravan P0740

Tiny
RONSON
  • MEMBER
  • 2000 DODGE CARAVAN
  • 3.3L
  • V6
  • FWD
  • AUTOMATIC
  • 321,000 MILES
I recently have a check engine light. When I checked it I had a P0700 trans. Trouble and a P0740 possibly torque converter. I had two things prior to this. First the window regulator went out and I disconnected the battery. While in the driveway I noticed a slight transmission leak. I was able to secure the pan bolts and looks like I have corrected the leak. I have a fairly new gasket as I changed the fluid and filter back I n July. After the wife drove it on the freeway it threw a code. I read what I could find on it and added some fluid, it was about half a quart low. I reset the code and drove it around town and two short trips on the freeway for about 10 miles. She drove it again today and it threw the same code again after about 20 miles on the freeway. Any ideas. Thanks in advance for the help.
Monday, January 5th, 2015 AT 6:16 PM

5 Replies

Tiny
CARADIODOC
  • MECHANIC
  • 34,072 POSTS
P0740 - Torque Converter Clutch Circuit Malfunction

There's a whole book related to diagnosing these fault codes. You can start by watching if the engine speed drops about 200 rpm once the engine is warmed up and the transmission is in third or fourth gear. If you aren't sure, hold the accelerator perfectly steady at highway speed, then tap the brake pedal with your left foot. You should see engine speed pick up 200 rpm, then drop right back down one or two seconds later.

The fault code only indicates the circuit that needs further diagnosis. Don't assume any parts are defective yet. The first thing to look at is wiring and connectors. Look for signs of corrosion on the connector pins.
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Monday, January 5th, 2015 AT 6:24 PM
Tiny
RONSON
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Thanks. I have driven it and held the speed at 65 m.P.H. And tapped the brake with my left foot and did't see any RPM change on the tach. I will check the connectors tomorrow if possible.
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Monday, January 5th, 2015 AT 6:44 PM
Tiny
CARADIODOC
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  • 34,072 POSTS
Also, if you have access to a scanner, you can view live data to see if the Engine Computer is commanding the lockup clutch on. If it is not, one section of the brake light switch could be stuck, the computer's coolant temperature sensor could be reading an overheating condition, or there could be some other requirement that hasn't been met.

If the lockup clutch IS being commanded on, the fault code could be the result of no drop in rpm was seen. Most of the time that's a result of wiring and connector problems, but the solenoid could be bad too.
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Monday, January 5th, 2015 AT 6:52 PM
Tiny
RONSON
  • MEMBER
  • 77 POSTS
Just an update, I have replaced the solenoid pack on the transmission as advised by a mechanic locally and have checked and cleaned the connector at the solenoid and the in and out transmission connectors. I drove it all over town for the past week and no light until today after driving about 32 miles on the freeway the light is back on. So if I cannot get an on board reader what should I shoot for next? Brake light switch or? Thanks again for all the help. I appreciate it.
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Tuesday, January 27th, 2015 AT 4:11 PM
Tiny
CARADIODOC
  • MECHANIC
  • 34,072 POSTS
The first thing is to read the fault codes to see if the same one came up. Next is you have to have a scanner to tell the computer to command the various solenoids to turn on and off so tests can be done in those circuits. It's almost impossible to do that when the vehicle is standing still, and it's not practical to take measurements under the hood while driving down the highway.
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Tuesday, January 27th, 2015 AT 6:54 PM

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