Trans codes 0740 & 0785 help
 

I realized this is the better topic for this question...

I recently finished a swap install. All is well except these two codes that keep popping up. 0740 & 0785.
I've checked the wiring and no shorts. Tested the pins for the 2-3 shift solenoid (T, E, and S). All good resistance values. Have the VSS plugged in, brake switch is hooked up (normally closed) circuit.
PCM was reprogrammed by Brendan @ LT1swap.com
Process of elimination...
Just confused as to where to go next.

Any ideas (logical ideas)?

Re: Trans codes 0740 & 0785 help
 

I responded to your other thread,

Just a thought....But if you are running a 4L80E harness with a 4L60E trans & ECM.....Those codes will set because the 4L80E does not have a 3-2 downshift solenoid or a TCC solenoid,

Check the harness for pins "T" & "U" at the trans plug.

Re: Trans codes 0740 & 0785 help
 

Oh, I see what you're saying. Maybe the pins in the trans plug are located in different positions. I'll check that too.

Re: Trans codes 0740 & 0785 help
 

You did check for Ignition power on pin "E"? Should set more codes than that, But Tuners like to turn off alot of stuff the really dont need to.

Re: Trans codes 0740 & 0785 help
 

I did.
I am going to get some time today to crawl under there and check the wire orientation as well as follow the wires back to the PCM to make sure they are all in the right place.

Re: Trans codes 0740 & 0785 help
 

Okay, I mapped the wiring from the trans plug to the PCM/power source and this is what I have.
conn. A - Lt. Green goes to #48 PCM (green)
conn. B - Yellow/Blk goes to #47 PCM (green)
conn. C - Red/Blk goes to #6 PCM (green)
conn. D - Lt. Blue/Wt goes to #8 PCM (green)
conn. E - Pink goes to keyed 12V power source
conn. L - Yellow/Blk goes to #51 PCM (green)
conn. M - Gray goes to #53 PCM (blue)
conn. N - Pink goes to #63 PCM (green)
conn. P - Red goes to #18 PCM (blue)
conn. R - Dk. Blue goes to #17 PCM (blue)
conn. S - Brown goes to #2 PCM (green)

no wires in "T" or "U" pins.

Re: Trans codes 0740 & 0785 help
 

You have a 6.0/4L80E engine harness!! You can fix it fairly easy, I will look it up & get back to you.

Re: Trans codes 0740 & 0785 help
 

4L60E

conn. A - Lt. Green goes to #48 PCM (green)
conn. B - Yellow/Blk goes to #47 PCM (green)
conn. C - Red/Blk goes to #6 PCM (green)
conn. D - Lt. Blue/Wt goes to #8 PCM (green)
conn. E - Pink goes to keyed 12V power source
conn. L - Yellow/Blk goes to #51 PCM (green)
conn. M - Gray goes to #53 PCM (blue)
conn. N - Pink goes to #63 PCM (green)
conn. P - Red goes to #18 PCM (blue)
conn. R - Dk. Blue goes to #17 PCM (blue)
conn. S - White goes to #79 PCM (blue)***
conn. T - Tan/black goes to #42 PCM (green)***
conn. U - Brown goes to #2 PCM (green)***

Take the pin out of Pin "S" & install it in Pin "U"

Run a New wire from pin "T" to #42 PCM (green)
Run a New wire from pin "S" to #79 PCM (blue)

Re: Trans codes 0740 & 0785 help
 

Will do.

I'll get back with the results when it's done.
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Re: Trans codes 0740 & 0785 help
 

Got it done.
No more codes!

Thank you so much for your help.

Time to tie up the wires and test drive.
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