0743 torque converter clutch circuit??

[dracing70]

well been trying too spool the puller and at around 2600-2800 the torque converter keeps locking on its own and im getting a 0743 code which is a converter clutch code. the truck has a 3000 stall precision in it and a bt lockup box but it keeps locking on its own prematurely. also im starting in 4th gear. any thoughts?????

 

[LWATSON]

Does the BT lockup box you have automatically lock up at a given throttle position? 2800 rpms may take enough throttle to put you in auto lockup?

 

[dracing70]

Does the BT lockup box automatically lock up at a given throttle position? 2800 rpms may take enough throttle to put you in auto lockup?

I'm not sure I need to talk to Ben. I have a message in to him. What about the code though. I unplugged the box and got the same result. The only thing that has changed is the converter is fresh back from precision with the higher stall and steel stator and billet shafts have been installed.

 

[LWATSON]

When you say you unplugged the box, did you reattach the TCM wires that get cut and spliced into the lockup box harness?

 

[LWATSON]

I just checked some info, says the auto lockup function is set at 95% throttle, I doubt that's whats causing your issue.

 

[dracing70]

When you say you unplugged the box, did you reattach the TCM wires that get cut and spliced into the lockup box harness?

R there wires that get cut or only spliced into??? But either way no

 

[LWATSON]

Best I can remember there is one wire that gets cut and each end is spliced to a separate wire going to the controller. I didn't know the truck would operate properly with the box disconnected unless the wire was reattached.

 

[LWATSON]

My first thought was you were hitting the throttle position where auto lockup occurs, but the more I think about it it's very unlikely your going to 95% when your building boost.

 

[dracing70]

My first thought was you were hitting the throttle position where auto lockup occurs, but the more I think about it it's very unlikely your going to 95% when your building boost.

No more like 20 percent. I don't get it unless precision did something wrong with the converter. But it seems electrical.

 

[LWATSON]

Seems strange, My converter stall is probably about the same as yours, I've seen 3100-3200 rpm's when building boost at the track, even at that rpm it wasn't trying to push through the breaks.

 

[dracing70]

Seems strange, My converter stall is probably about the same as yours, I've seen 3100-3200 rpm's when building boost at the track, even at that rpm it wasn't trying to push through the breaks.

It's not pushing brakes at all it starts to spool and just before it comes alive the converter locks abruptly like a shift and pulls it down.

 

[boominator]

try unplugging the trans connector at the back of the trans it will hydraulically go to third gear and try what you were doing before and if the converter still locks its not electrical problem but a problem with the trans or tc :thumb:

 

[Mike L.]

P0743 usually indicates a shorted F trim solenoid.

 

[dracing70]

P0743 usually indicates a shorted F trim solenoid.

Which one is the f trim mike ? And is it common for this to happen out of no were ? The truck sat all winter and was fine when parked. Also shouldn't I be able to hold the converter in the unlock position as long as I desire with the BT lockup box ??

 

[Mike L.]

Which one is the f trim mike ? And is it common for this to happen out of no were ? The truck sat all winter and was fine when parked. Also shouldn't I be able to hold the converter in the unlock position as long as I desire with the BT lockup box ??

F trim is the furthest solenoid from the 2 trim solenoids. First one on the driver side. Yes they can short out anytime.

 

[dracing70]

F trim is the furthest solenoid from the 2 trim solenoids. First one on the driver side. Yes they can short out anytime.

Ok check with a ohm meter correct?? I'm not sure if it's setting. 0743 as a hard code or if it's only in the background. And is there any truth to pulling the electrical connector and it automatically defaulting to third gear to eliminate electrical issues from the equation ??

 

[Mike L.]

Ok check with a ohm meter correct?? I'm not sure if it's setting. 0743 as a hard code or if it's only in the background. And is there any truth to pulling the electrical connector and it automatically defaulting to third gear to eliminate electrical issues from the equation ??

Pulling the harness connector will not help you with a p0743 as the TCM will read an open circuit on every solenoid and switch on the valve body. ohm it out or just change it. They're cheap.

 

[duratothemax]

Send me an email with your phone number and we can talk about this and figure out the issue. [email protected]

Ben

 

[dracing70]

Send me an email with your phone number and we can talk about this and figure out the issue. [email protected]

Ben

Ben tried to give u a shout. I left you two emails with my number. Give me a call thanks

 

[dracing70]

Mike I swapped out trim valve the old one seemed fine 11 ohm but I put new in regardless. Have not ran truck yet till tomorrow however I also air checked trim solonoids and it worked great. Checked resistance at tranny plug to check wiring and all good. Checked connections at tcm all good. The only thing different from last year is the precision converter that I got from you was sent this winter to precision to be restalled and stator upgraded to steel. Now I sent a video to you of the fluid and it looks quite shiny??? And lil dark considering there are zero miles on it just about four attempted boosts in the drive. Oh and I refreshed the c2s. Can a jacked converter usually cause the 0743 code, sudden lunge while boosting with rpm drop and dark fluid???