Allison 5sp: P0703 Code! Torque conv?

NKlamerus

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Jan 31, 2014
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I'm not sure if this is in the right spot but I'll give it a try.

So I plugged in my hypertech max energy a few days ago to sync tune 2 and beforehand it had to wipe code p0703 and u1000. I didn't think anything of it and wiped the tunes. Synced it. And drove off. After getting home and looking up the DTC's I realize they fit! At least the cruise control part....it doesn't work. I have replaced the turn signal knob, the brake switch today as well as cleaned the connections(what a PITA), all my gears run great, my shift illumination is bright and dims with the dash as usual, tow/haul works as usual as well as the braking, . I have also cleaned out 1 of the 2 electrical connections on the driver side of the transmission. (The smaller one) with no avail. Both switches are covered in what I'm guessing is tranny fluid which is also all over the back of the tranny pan. (Fluid and filter were swapped not even 6 months ago) 2 of the 3 brake lights work(the cab light doesn't get brighter when brake is applied?)

I guess the main gear switch(forgot the name) on the driver side of the transmission is the next step?

The other half of the code has to do with the torque converter?

Any help is greatly appreciated.

2002 2500HD LB7 4x4

2002 LB7 HypertechMaxEnergy. 4x4. Ranchands. 33Coopers. Stupid is a Stupid Does.
 

Harbin_22

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Dec 4, 2010
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Southern Indiana
P0703 is Brake Switch B circuit error. Sounds like there is something wrong with it or wiring to it. What is making you think there is something wrong with the converter.
 

NKlamerus

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Jan 31, 2014
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I looked up the DTC'S on DuramaxForum on their transmission shop thread with a list of every dtc, is it wrong? uploadfromtaptalk1391661012520.jpg

2002 LB7 HypertechMaxEnergy. 4x4. Ranchands. 33Coopers. Stupid is a Stupid Does.
 

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NKlamerus

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Jan 31, 2014
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The truck also has a Curtis brake controller? I don't own a trailer with brakes so maybe I can disconnect it and see if it's causing a short in the system or something.

2002 LB7 HypertechMaxEnergy. 4x4. Ranchands. 33Coopers. Stupid is a Stupid Does.
 

NKlamerus

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Jan 31, 2014
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I replaced it already just to make sure all the contacts were good. Still nothing changed
 

NKlamerus

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Jan 31, 2014
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Well it was partly faulty, I took is apart once it was off and the spring had cracked in 2 peices anyway. I guess that's the next step.