I've got 1765 0743 0382 for codes.  I looked them up but reading through the write-ups it really goes over my head!  Could someone help me know where to start with pinpointing my problem? The reason I checked for codes is when I'm using my exhaust brake the TC always lockup in second.  Sometimes does, sometimes doesn't.  On the times that it doesn't lock I can force lockup with my mystery switch.

Did you check the relays in the power distribution box under the hood? The 2 codes showing are circuit related, sounds like either a bad connection/relay somewhere .

How are you achieving second gear lock up? A custom valve body/lock up controller? That is the only way I'm aware of. I would really love that function.

Edited February 26, 201411 yr by diesel4life

I customized the valve body myself according to a thread I found on CF. I will check the relays. I have the one relay out and a jumper wire installed to make the lockup switch work...

I put the trans relay back in place of the jumper wire and that didn't work at all.  The tranny felt very sluggish and the TC didn't lockup at all.  Another dimension to this is that when it's really cold outside and before the tranny is warm the TC locks up right away.  So if I drive away in D it right away hits lockup and stalls the truck.  I have to start in 1 and get up some speed, then shift into 2 etc.

 

It threw a 0753 code when I had the relay back in.

Bump..

Is there no Trans gurus here that can help me with this?

the 0753 is most likely due to the 1765 code. I think your problem is either in the relay or in the circuit between the pcm and the relay. Have you swapped relays out to eliminate the possibility of a bad relay? You can use one in the pdc under the hood. Also check for voltage at terminal 86 in the relay control circuit where the relay plugs in. I think its c1 on the relay.