Truck dies when accelrating hard

Old 01-12-2019, 07:11 PM
dnt1010's Avatar
AutismSpeaks Advocate
Join Date: Oct 2018
Location: TN
Posts: 160
Default Re: Truck dies when accelrating hard

Originally Posted by clayhardock View Post
Got the new scanner and it did come up with a new code from the Hybrid module, p0730 gear ratio incorrect. Using the new software I plotted the RPM and it shows that the engine RPMs are flaring as it goes into 4th gear when under heavy load. I'm guessing that 4th gear is just starting to go out and only shows when shifting under heavy load. I'm guessing the hybrid computer sees the spike in RPM and is shutting down the system.

Its frustrating though that the system has to shut down, other wise I'd just back out of it when I feel it slipping, it would also make it much easier to diag.
So has anyone had their trans rebuilt? I've seen a few cases where the trans was replaced by a factory rebuilt unit. I've also looked around and can not find a rebuild kit anywhere online.
Dang it man that is not good news. From what I have read these are some of the most complex transmissions ever built for a passenger vehicle and only around 30,000 were ever manufactured.
I saw one post where a fella had spent $5,000.00 for a replacement from a dealer. I just did a partial fluid change on mine today. It has a drain plug in the trans bottom cover and I pulled it and it drained out 8.31 quarts of Dexron VI. I refilled with fresh fluid the same amount. I used an electronic scale to weigh it. The fluid looks pretty good, it still is red with a slight brown color. I was afraid to do a flush since I do not know when or how many times it has been changed over its 200,000 mile life. If you find a good source that can rebuild these for a reasonable fee please post the information. As these vehicles age there will be many more people needing that service....
Old 01-12-2019, 10:50 PM
Thread Starter
Join Date: Dec 2018
Posts: 9
Default Re: Truck dies when accelrating hard

I pulled the pan on mine yesterday, fluid looked great, normal amount of fuzz on the magnet, no large chunks. Pulled TECMS (the solenoid/electrical half of the valve body with the TCM), cleaned and inspected, looked fine.

Looking at the parts breakdown it doesn't look anymore complicated to rebuild than any other 4spd transmission. The 4th gear is bolted onto the back of the trans and looks like it could be removed with the trans still in the vehicle.

Things holding me back:
Parts supply- where do I get parts, I think I've found the ATRA/Transtar parts rebuild kit number which means any trans rebuild supply shop should be able to order a rebuild kit. Will have to make some calls on Monday and see if its available and price.
Pulling the whole trans myself isn't really feasible as its apparently a very heavy unit and I don't have a trans jack.
Not 100% sure the problem is the 4th gear clutch, could be the control circuit not applying the correct apply pressure. If it is really an electrical problem then I could truly be screwed as a replacement would need to be programed. I can assign VIN numbers to new modules but thats it.

At this point I'm thinking my best bet is just to drop the t-case and remove the rear 4th gear housing and physically see if the clutch is toast. If it is, great! Replace and go. If it looks ok then I'd be back to square 1.

Link to a trans rebuild catalogue that lists rebuild parts and pics:

A GM service repair book that I'm contemplating buying:
Old 01-13-2019, 08:28 AM
dnt1010's Avatar
AutismSpeaks Advocate
Join Date: Oct 2018
Location: TN
Posts: 160
Default Re: Truck dies when accelrating hard

You seem to be a "Can Do" type person. Most people at this point would just throw up their hands. I had read somewhere that the 2ML70 is an "Allison design" based upon HD bus hybrid application which has been known to run stop and go 24 hour a day 7 days a week for 100s of thousands of miles trouble free. Please let the forum know what you end up doing on this, Maybe you will find that your issue is not even trans related and the code is leading you in the wrong direction? Either way I applaud your tenacity.
Old 01-13-2019, 11:28 AM
Thread Starter
Join Date: Dec 2018
Posts: 9
Default Re: Truck dies when accelrating hard

I'm a HD mechanic by trade so ripping stuff apart doesn't scare me and at this point and I don't have much to loose. I cann't in good conciseness sell it to anyone so the only option are to fix it, scrap it, or send it to auction. I've been curious about hybrids for awhile now so this is a good learning experience for me. Just frustrating trying to find info on them. Usually stuff I work of my own there are good online forums of info and self help tech, but these seem to be pretty rare and not many people wrenching on them themselves.

More technical reading:

Skip to pg 47:
Old 01-19-2019, 06:34 PM
Join Date: Feb 2018
Posts: 32
Default Re: Truck dies when accelrating hard

Does the Chrysler version have the M1 - M4 manual gear selection option? Have you tried forcing it to stay in M3 and do the same procedure you used to get the stall initially?
Old 01-22-2019, 02:14 PM
Thread Starter
Join Date: Dec 2018
Posts: 9
Default Re: Truck dies when accelrating hard

No is does not, I wish it did. It does have the old style PRND21 selector. Next time I'm out with it I will put it into 2 and see what happens. Unfortunately the problem is with the 3/4 shift.
Related Topics
Topic Starter
Last Post
Toyota Camry Hybrid
06-29-2007 05:32 PM
HCH II-Specific Discussions
04-20-2007 04:09 PM
Hybrid & Related News
01-01-2007 12:37 PM
Journalism & The Media
03-21-2006 03:12 PM
ice weasel
Toyota Prius
06-14-2005 09:19 AM

Thread Tools
Search this Thread
Quick Reply: Truck dies when accelrating hard

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to and affiliated sites.