Allison transmission shop in HB area?

Dylanshaffer

Dylanshaffer

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Started having some issues with my truck today. It’s a 2014 chevy 2500 duramax with the 6 speed allison. Check engine light and traction control lights came on today. In drive the trans won’t shift past first (I think it’s in first) and doesn’t seem to lock up the torque converter. Additionally the gear indicator on the dash no longer indicates what gear it’s in and the trans temp reads - - -, so the trans doesn’t seem to be passing data to the dash. It shifts super hard going from Park to reverse and drives and in manual mode it won’t shift. Looking for recommendations on potential causes and good shops in the Huntington Beach area. The truck has 75k miles, trans fluid looks good and I changed it about 15k ago.
 
Could be a number of issues to be completely transparent with you and you need a tech 2 scanner to read out TCM codes to really figure out what is going on. But your are right their is a communication error between the transmission/t-case to the TCM. So its going to be something with the wiring, valve body or TCM. Unfortunately, the LML's are known for straight up TCM failures. But I would start by checking out the following:

1. Check transmission/t-case harnesses for damage or fresh oil saturating them.
2. Check your TCM connector for damage.

When something similar happened to my lbz duramax, it was several solenoids and the NSBU switch failing in the valve body. My friend had a similar issue on is LMM and it ended up being a severely toasted t-case that ruined his t-case harness. The issue was caught because his harness was covered in fresh oil. He ended up needing a new t-case because it was not worth rebuilding.

I have someone that I highly recommend but he is out in Menifee. He's a retired master GM Tech and works out of his home shop. He diagnosed my truck and my friends very quickly. He is straight with you and is done when he says he will be done. DM me and I can share his contact information with you if you are interested. A lot of people may direct you to Inglewood Transmission in LB, but they will try to just sell you on rebuilding your transmission. In which case you may not need to. Great shop for rebuilding your trans though... not so much for troubleshooting.
 
Kraut_n_Rice said:
This is who I had do my full build many years ago. Very involved in pioneering the high HP builds.

Inglewood Transmission: Expert Automotive Transmission Repair

Inglewood Transmission specializes in rebuilding & customizing Allison, Dodge/Ram & Ford transmissions. Quality parts & expert service since 1964. Visit us in Long Beach, CA.
inglewoodtransmission.com inglewoodtransmission.com
Click to expand...
I had Inglewood do mine a few years ago. VERY HARSH shifting and they would not make it right. Major attitude. I would never use them again.
 
ScottJ24 said:
I had Inglewood do mine a few years ago. VERY HARSH shifting and they would not make it right. Major attitude. I would never use them again.
Click to expand...

I had the opposite experience. Might was amazing for a year or two. Then it was acting like the TC was staying locked. He said to bring it out. Mind you I live in Phoenix. Meet him at his shop first thing in the morning.

He had a new TC waiting and swapped it first, nope. Ended up being the freeze plug in the end of some valve. They had to take the trans out twice that day. Had me back on the road before closing time.
 
Might read through this.

J

Thread 'TCM went bad, no stock anywhere in the country ***UPDATE***2nd update--not good!!'

on my 70 mile way in to work and at mile 10 i hit a bump in the road (basically a little jump) at 45 mph and my traction control light came on, i thought i caught air, but a little while later it was still on, then the stabilink message appeared and i couldn't go, no throttle but had reverse. this was 5:15 AM  after coasting backwards across three lanes down a slight hill into a parking lot I did a code scan and it said i had lost TCM communications,  i checked a relay, checked the fuse, checked for rats chewing wires as i live in the sticks, nothing  i called AAA and they towed me to...
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Kraut_n_Rice said:
I had the opposite experience. Might was amazing for a year or two. Then it was acting like the TC was staying locked. He said to bring it out. Mind you I live in Phoenix. Meet him at his shop first thing in the morning.

He had a new TC waiting and swapped it first, nope. Ended up being the freeze plug in the end of some valve. They had to take the trans out twice that day. Had me back on the road before closing time.
Click to expand...
The issue with mine was the shifts were all pretty hard but the 3-4 shift under a hard pull, felt like you got hit in the back with by 2 sledge hammers a split second apart. My wife wouldn't ride in it until I got it re programmed. It is still a VERY firm double tap but is marginally tolerable.
 
Kraut_n_Rice said:
Might read through this.

J

Thread 'TCM went bad, no stock anywhere in the country ***UPDATE***2nd update--not good!!'

on my 70 mile way in to work and at mile 10 i hit a bump in the road (basically a little jump) at 45 mph and my traction control light came on, i thought i caught air, but a little while later it was still on, then the stabilink message appeared and i couldn't go, no throttle but had reverse. this was 5:15 AM  after coasting backwards across three lanes down a slight hill into a parking lot I did a code scan and it said i had lost TCM communications,  i checked a relay, checked the fuse, checked for rats chewing wires as i live in the sticks, nothing  i called AAA and they towed me to...
  • Like
Click to expand...
I had this exact problem with my 2011 gmc 2500. Ended up being the TCM. $800 and a reprogram later the truck was driving again.
 
www.dartcotransmission.com

Anaheim, California

The Anaheim location has been servicing Allison transmission customers in Southern California since 1978. Dartco Transmission is currently one of the larger authorized Allison transmission rebuilder and parts distributors in the Los Angeles metropolitan area. With several major airports and sea...
www.dartcotransmission.com www.dartcotransmission.com
 
Thanks for the tips and recs! I had it towed to Leon’s transmission in garden grove yesterday, I’ll report back on how it goes.
 
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