Shift range inhibited on cold starts.

[Scooner]

In the last couple of weeks when below -15c after cold starting my truck the voltage is around 9-10 volts for a couple of min. Then returns to 14v but in this time the check engine light comes on and says shift range inhibited on the dash. After clearing code p0751 truck drops into gear and drives normally. I have already had the truck to the dealership $700 later and same problem. And this morning my dash was saying service charging system on cold start but went away after warming up and is still locking out the trans. They tested a both batteries and cleaned and checked all connections. And reflashed TCM. I really dont want to take it back to the stealership...

[Hibneck1]

Im not sure why it would have the check engine light but the allison does have a shift range inhibitor to help with warm up in real cold weather... Just one more reason I love this trans! http://www.allisontransmission.com/s...t=SA3931EN.pdf

[TBone]

I think the shift range inhibit is temp induced, once the tranny warms up it should be fine. If you have your book that came with it read about the allison....I think its to prevent overpressureizing the trans when fluid temps are below a certain temp..


Now I see the other post I remember, I'm wrong.

[Scooner]

It will still say shift range inhibited after running on high idle of 1200rmp for 15min. And trans temp of over 25 celcius. It will only drive after clearing codes.

[KB3MMX]

If your batteries are dropping that low, it needs new ones regardless of what the dealer says. It's going to have reduced voltage until the intake grid heater shuts off but if the batteries are weak, it'll be real low.

The transmission will also limit it's operation in cold weather until it's warm enough to prevent damage from lack of oil flow.

Also, going to synthetic engine oil will reduce electrical strain when cranking and improve flow in the winter. Synthetic Allison Transynd ATF would also be a good upgrade...