Allison 6sp: LMM p0776 reverse works but no forward gears

pudge27george

New member
May 3, 2019
3
0
1
Truck has thrown p0776 a couple times. Converter would not lock in under wot would limp into 2 or 3, clear code and truck would run and shift just fine. Now truck only goes in P, R, and N. Putting into either D,M, or 1 all results in the same dash shows shift inhibited return to N
 

pudge27george

New member
May 3, 2019
3
0
1
Transmission is fully stock. Fluid changed at regular intervals. Truck has 265,000. Highest temp ever was 206. Never pull anything just drive it hard. I’ll answer any and all questions. Trans tune by ppei, fleece lines, and a ppe deep pan.

Truck is medium modified 650 rwhp

I know that is entirely too much for stock trans.

Looking for a reputable builder in central Florida. I have purchased rebuild kit to handle 800 hp. All seals, gaskets, solenoids, internal harness new. Billet input, intermediate, and out shafts. PPE performance cooler, triple disc billet converter with billet stator, billet flex plate, arp flex plate bolts. Also looking for advice on what else might be needed to make this one and done.
 
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