TC not locking
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Senior User
Joined: Aug 2012
Posts: 307
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From: thornton CO
TC not locking
Funny shifts and OD light blinking. Have p0741 and p0743 codes. Checked wiring and no visible damage. Checked continuity on the purple-yellow TC wire from connector under hood and at Trans and their is none.?? Please advise.
Also will I hurt the Trans driving this way if the temp stays in check?
Also will I hurt the Trans driving this way if the temp stays in check?
Laughing Gas
Joined: Oct 2013
Posts: 861
Likes: 7
From: AZ
Can't help with your problem but...........
My 1988 Suburban was having trans troubles where the TC would lock and unlock twice a mile and a trans shop showed me how to make my TC never lock up and that was this spring. It only runs a couple hundred rpm higher and tiny noticeable loss in mileage, maybe .5 mpg less. But what's 13.5 from 14? Trans temps have been fine but I don't tow with it either.
My 1988 Suburban was having trans troubles where the TC would lock and unlock twice a mile and a trans shop showed me how to make my TC never lock up and that was this spring. It only runs a couple hundred rpm higher and tiny noticeable loss in mileage, maybe .5 mpg less. But what's 13.5 from 14? Trans temps have been fine but I don't tow with it either.
Veteran/Sheepdog
Joined: Feb 2012
Posts: 6,047
Likes: 110
From: Western AR
TSB says:
2001-2002 Trucks with 4R100 Torque Converter Clutch Solenoid Codes:
Some trucks build between 1-1-01 to 5-1-02 may exhibit a flashing OD light and possibly harsh shifting, with any or all of the following trouble codes: P0740, P0741, P0743, P1744. This may be due to high resistance in the torque converter clutch solenoid, which results in lower torque converter lock pressures. The transmission solenoid body should be replace with P/N F81Z-7G391-CB to correct. Broadcast Message 3559
This has fixed the problem for MANY guys with your same symptoms/codes. Best price I could find just now was
2001-2002 Trucks with 4R100 Torque Converter Clutch Solenoid Codes:
Some trucks build between 1-1-01 to 5-1-02 may exhibit a flashing OD light and possibly harsh shifting, with any or all of the following trouble codes: P0740, P0741, P0743, P1744. This may be due to high resistance in the torque converter clutch solenoid, which results in lower torque converter lock pressures. The transmission solenoid body should be replace with P/N F81Z-7G391-CB to correct. Broadcast Message 3559
This has fixed the problem for MANY guys with your same symptoms/codes. Best price I could find just now was
Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,731
Likes: 2,658
From: SE Florida
Visibly checking the wiring harness will only find the most obvious problem.
You just proved that your visual check was a waste of time. You've located the problem, it is a broken wire in the stretch you checked. You can try to find the problem spot and fix it, but I'd just run a new wire.
No, it will not.
No, it will not.
Veteran/Sheepdog
Joined: Feb 2012
Posts: 6,047
Likes: 110
From: Western AR
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Senior User
Joined: Aug 2012
Posts: 307
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From: thornton CO
Is their a way to check resistance on the solenoid, and if so what should it be? I'd hate to replace the solenoid pack if it's still good. Maybe just a case of debris stuck in their.?
Found this video of a complete tear down and the guy mentions it around 17:30.
Found this video of a complete tear down and the guy mentions it around 17:30.
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