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?

 

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.

 

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

 

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.

 

Thank you for your input Mark. I will replace wire and update.

 

So I replaced wire and it's still not locking. Where do I go from here?

 

Refer to the TSB next is what I would do.

 

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.

 

 

The resistance should be 10-20 ohms, as you have a PWM TCC solenoid.

 

Thanks guys. Can I test at the connector outside the Trans or can it only be done by dropping the pan and checking the pack?

 

The Connectors are external of the Case.

 

Well, now it won't go into drive. Backed out of driveway to go to work and stalls every time I shift to drive. I backed around the block and back in driveway now.

 

I also found this diagram that gives wire colors. My connector does not match this or the one shown in the post above, so not sure what to check.

 

Checking the Violet/yellow with every other, I get nothing.