1997 Dodge Ram torque converter code P0740

Tiny
J.STIEG
  • MEMBER
  • 1997 DODGE RAM
  • V8
  • 4WD
  • AUTOMATIC
  • 155,000 MILES
I am trying to troubleshoot a torque converter problem. It seems like the rpms are a little high while cruising. Can I do a circuit or solenoid test, before checking into the transmission or torque converter. What should I try first?
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Wednesday, October 20th, 2010 AT 10:13 AM

24 Replies

Tiny
DOCFIXIT
  • EXPERT
Hi
Need a scan tool to do diagnostics. What can do check fliud level good color red clear?PTU connection tight on side trans? Are tires larger than stock?
Let me know
Thanks for donate
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Wednesday, October 20th, 2010 AT 11:47 AM
Tiny
J.STIEG
  • MEMBER
The transmission fluid looks red and clear, connections are tight, tires are stock 265 75 r16, But there is a problem with the torque converter locking up. I have a scanner and got code p0740. What next?
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Wednesday, October 20th, 2010 AT 11:07 PM
Tiny
DOCFIXIT
  • EXPERT
What you have is a code reader a scan tool interfaces with PCM and can diagnose failures in control circuits. Also will need to have pressure tests done on trans to determine if pressure loss is causing problem.
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Thursday, October 21st, 2010 AT 9:17 AM
Tiny
J.STIEG
  • MEMBER
I Have a code reader, it may be a scanner as well, I payed $100 for it. Also I am ready to do a pressure test. Can you give me specifications. Thanks
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Thursday, October 21st, 2010 AT 12:16 PM
Tiny
DOCFIXIT
  • EXPERT
Scan tool needed is like the one I use a Snap on MODIS and costs $9700.00. As for pressures check Drive /overdrive see figure to ID tap.


http://www.2carpros.com/forum/automotive_pictures/198357_Graphic_660.jpg


Remove overdrive clutch tap install 300psi gague. Have vehicle wheels off ground trans in drive increase engine speed untill 3-4 shift NOTE pressure
68-72 psi at closed throttle and 90-120 at 1/2 to 3/4 throttle MAX 130psi.
If pressures not reached the internal fluid loss
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Thursday, October 21st, 2010 AT 12:36 PM
Tiny
J.STIEG
  • MEMBER
I did a pressure test on the overdrive clutch tap, and when in drive, the pressure was around 50psi at closed throttle and at 85psi at throttle, and pressure readings where the same going down the road. Do you think fluid is getting by a seal somewhere in the transmission?
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Friday, October 22nd, 2010 AT 1:15 PM
Tiny
DOCFIXIT
  • EXPERT
Yes valve body or lockup clutch in torque convertor
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Friday, October 22nd, 2010 AT 3:17 PM
Tiny
J.STIEG
  • MEMBER
Do you think I should replace the torque converter? Is there any thing else I can test or pressurize with the pan off? If there is, give me a diagram and spects and I will do it. Thanks!
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Friday, October 22nd, 2010 AT 4:08 PM
Tiny
DOCFIXIT
  • EXPERT
With pan off check for clutch material, silver metal shavings.
Also pull off TCC solenoid see if sealing ring is good and plug on shift valve is in and tight.
Sending diagram but it is transfering small try and move to like a Microsoft works see if you can enlarge


http://www.2carpros.com/forum/automotive_pictures/198357_Graphic_668.jpg


#25 and #15
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Sunday, October 24th, 2010 AT 2:32 PM
Tiny
J.STIEG
  • MEMBER
There is a little metalic sludge on the magnet in the pan, I see this on a lot of transmissions and seems normal. Solenoids look fine and operate with 12v applied. Checked connections and wire harness and there are no opens. It could be the valve body or torque converter like you said, but which one? I think I will replace the torque converter soon.
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Monday, October 25th, 2010 AT 5:01 PM
Tiny
DOCFIXIT
  • EXPERT
With no other shift problems and there is a pressure increase that trys to 3-4 shift think fluid leak could be Teflon "O" rings on input shaft. When you pull Torque off inspect rings if cut or deformed that's problem. If lock up piston was faulty would see A LOT of metal in pan.
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Tuesday, October 26th, 2010 AT 11:51 AM
Tiny
J.STIEG
  • MEMBER
Ok, thanks I will look at the seals.
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Tuesday, October 26th, 2010 AT 2:55 PM
Tiny
J.STIEG
  • MEMBER
I am putting the valve body back together and I found a small steel ball in the pan I drained fluid in. I dint see it come out during disassembly. I don't see where it goes. I dint think that this transmission had check balls. Can you check and see? It is a 46RE, thanks
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Tuesday, October 26th, 2010 AT 4:06 PM
Tiny
DOCFIXIT
  • EXPERT
See diagram ues a dab of Vasoline to hold in position


http://www.2carpros.com/forum/automotive_pictures/198357_Graphic_674.jpg

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Tuesday, October 26th, 2010 AT 5:18 PM
Tiny
J.STIEG
  • MEMBER
I have the torque convertor off now, and I see the O ring in the bottom of the torque convertor looking down the hole. It doesn't look bad, but it is hard to see.

I might try too pressure test the torque converter to see if I can build up pressure on clutch piston just for fun. I think I will machine a piece to apply pressure. Is this something that is normally done to converters after taking them off?
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Thursday, October 28th, 2010 AT 9:47 PM
Tiny
J.STIEG
  • MEMBER
I pulled the pump off to look at rings on imput shaft and one is steel and the other one is Teflon I am going to replace them both before mounting transmission.
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Friday, October 29th, 2010 AT 5:09 PM
Tiny
DOCFIXIT
  • EXPERT
Been working was off line but yes air checking torque is done everytime a trans comes apart. But takes anadapter to get to line input. You can see on top end of input. You could have a Trans shop check torque save you hassel and expense of pulling back or replacing.
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Sunday, October 31st, 2010 AT 1:41 PM
Tiny
J.STIEG
  • MEMBER
I put two new seals on the imput shaft and blew back into the transmission, and a lot of air seem to be getting around them and coming right back in my face between the two splines, like the ones I took off. Is this normal?
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Tuesday, November 2nd, 2010 AT 8:15 AM
Tiny
DOCFIXIT
  • EXPERT
NO not normal take converter to trans shop have it tested
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Thursday, November 4th, 2010 AT 8:08 AM
Tiny
J.STIEG
  • MEMBER
A transmission tech looked at it, and pressurized it with adaptor and said it was within specs. So I mounted the trans back up with a new torque converter and imput shaft seals, and truck runs fine. RPMs drop like they should when converter locks up.

Every thing is fine except the "ABS and brake light" came on when performing test on day one. I had the rear tires off the ground and was spinning them at high speeds. What kind of reset tool do I need, or can I reset them another way?
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Friday, November 5th, 2010 AT 8:40 PM

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