Allison 5sp: P0748 P0778 and no power in 1st gear

[THEFERMANATOR]

Is it possible for these 2 codes to trip from low voltage during cranking? I'm getting my swap finished up and I'm getting these 2 codes but no check engine light from them. I've disconnected the connectors at the TCM and checked resistance and have 5.8 ohms on sol A and 6.0 ohms on sol B and no detectable shorts to ground or power. I'm currently only using 1 battery that has seen better days to run her as I my other group 78 won't fit now, I need a group 75 to clear the upper rad hose. I'm also having some other issues I believe are TCM related with no power in 1st gear only beyond 20% throttle. I've PM'd Brayden as he did my TCM for me, but the 2 codes have me scratching my head as to why they are popping up.

And they come up everytime during cranking. I can clear them and they won't return until I turn the engine over again.

 

[Mike L.]

Is it possible for these 2 codes to trip from low voltage during cranking? I'm getting my swap finished up and I'm getting these 2 codes but no check engine light from them. I've disconnected the connectors at the TCM and checked resistance and have 5.8 ohms on sol A and 6.0 ohms on sol B and no detectable shorts to ground or power. I'm currently only using 1 battery that has seen better days to run her as I my other group 78 won't fit now, I need a group 75 to clear the upper rad hose. I'm also having some other issues I believe are TCM related with no power in 1st gear only beyond 20% throttle. I've PM'd Brayden as he did my TCM for me, but the 2 codes have me scratching my head as to why they are popping up.

And they come up everytime during cranking. I can clear them and they won't return until I turn the engine over again.

These two codes will come up when the ignition is on and the main harness connecter at the trans is not connected.

 

[THEFERMANATOR]

I've cleared the codes since I had the trans unplugged. The resistance on the 2 solonoids is correct at the TCM connector and I can find no signs of a short in the harness. As for my low power in 1st I believe I have that one figured out as well. Seems 2 of my PENSACOLA remans are bad as the problem has gotten ALOT worse and does it in every gear now. followed by a raw diesel smell out the tailpipe with blue and white smoke now.

 

[THEFERMANATOR]

I ended up finally getting this all worked out and the SUB is up and running now. Ended up being bad injectors for the low power issue, and 2 new batteries took care of the 2 codes.