Allison limp mode when cold start

[ohkyguy]

I have a 2006 GMC 3500. My tranny is rebuilt using a Suncoast GMAX6pac and has a ml converter. I also have ml tranny cooler.

It has been going into limp mode as soon as I start it up when it is cold outside. I have tried to start it up and let it set running to warm it up and when I go get in it the check engine light is on and stuck in third gear. I can go ahead and get it to drive and I try shutting my truck down and restarting several times and using my programmer to clear the codes and I can get it to drive fine and later on the codes clear themselves.

I am thinking it is just electrical because I noticed my batteries are very weak here lately.
I am getting the following codes po751,po843,po873,po877 and po700.

Any ideas?
Thanks
Bobby

 

[Fastorange]

p0700 is just a genral code that comes on telling you there is a problem in the trans.. did you build it yourself or did someone eles do it? do you know if the taps were reset after the build?

 

[Fastorange]

Code: P0751
Modules: PCM
Description: 1-2 Shift Solenoid (SS) Valve Performance - No First or Fourth Gear

Code: P0843
Modules: TCM
Description: Pressure Switch C Circuit High

Code: P0873
Modules: TCM
Description: Pressure Switch E Circuit High

Code: P0877
Modules: TCM
Description: Transmission Pressure Switch 4 Circuit Low

 

[Mike L.]

Sounds like it's low on fluid. Check the level at 175 F in park. Read both sides of the stick and if one side is higher, use the lower reading as your index. Take 3 reading to be sure.

 

[ohkyguy]

Thanks Mike, I will recheck the levels again. I have checked and I am pretty sure it was fine. I believe you told me a while back to make sure it was half way between the hash marks. It would be very hard to check it at 175 degrees right now as it is only 30 degrees. I did start it up after it sat for a couple of days and the temperature was about 37 degrees and no codes and shifted perfect. It seems like it only has the issues when it is 31 degrees or colder outside. I will get as warm as I can get it and check the fluid levels. As always thanks Mike

 

[ohkyguy]

I had it built by a Clarke technician that has built hundreds of Allison trans. We used the SunCoast GMAX6PAC kit, ML converter and all brand new Allison solenoids. Not sure about taps but the tranny was done almost 2 years ago and has maybe 15,000 miles on it since full rebuild. Gonna check fluid level to make sure it is at proper level. I did use Transynd in it as well.

 

[Harbin_22]

Was it Joe at Clarke?

 

[ohkyguy]

Cold temps Allison limp mode

Well I hadn't had a problem since last winter. This winter when it gets around or below 31 degrees my check engine light comes on when I start my truck and transmission is in limp mode. The fluid level is spot on.
I have a 2006 GMC 3500. My tranny is rebuilt using a Suncoast GMAX6pac and has a ml converter. I also have ml tranny cooler.

It has been going into limp mode as soon as I start it up when it is cold outside. I have tried to start it up and let it set running to warm it up and when I go get in it the check engine light is on and stuck in third gear. I can go ahead and get it to drive and I try shutting my truck down and restarting several times and using my programmer to clear the codes and I can get it to drive fine and later on the codes clear themselves.

I am thinking it is just electrical because I noticed my batteries are very weak here lately.
I am getting the following codes po751,po843,po873,po877 and po700.

Any ideas?
Thanks
Bobby

 

[dieseladdiction23]

You still have weak batteries a year later?

 

[ohkyguy]

You still have weak batteries a year later?

Dieseladdiction do you have any value to add? As you can see I copied the post from a year ago. I replaced both batteries and yes they run down after setting for a week or so in the cold but not in the summer. It almost seems like lower voltage is causing the trans to throw codes and go into limp mode

 

[JoshH]

I just replace my batteries because I kept throwing a trans code when I started it when it was cold and the truck had been sitting for a while. Now that I got new batteries in it, I haven't had a problem, but I wasn't throwing the same codes as you. Not sure yours is the same problem, but it may be worth checking out. What kind of batteries did you install that are already giving you problems at less than a year old?

 

[MACKIN]

31 degrees isn't even that cold IMO. Brand new batteries (the correct ones) should have that spinning over fast with no issues unless you have something draining the batteries when it sits! I suppose if you would as suggested what are the battery specs?

 

[ohkyguy]

Okay today it was 18 degrees. Truck started fine. battery voltage was 11.7 volts according to my Edge. The check engine light came on when voltage showed 12.1 volts. I don't think the voltage had anything to do with it but I recorded it anyways. I got the same codes again. I checked the fluid level when cold and it is at the bottom of the has marks. This problem seems to happen when it is colder than 32 degress is what I have noticed. I can drive it in limp mode and reset the codes after it warms up and it is fine until I let it set and temperature drops below 32 degrees. I replaced the batteries last winter and have not had any battery issues until I let it set for a week or so. I do have something drawing on my batteries but I will work on that issue later.
I had seen a bulletin about the po873 and it has something to do with 32degrees which is exactly the temp when I have issues. I cannot find the bulletin that I had seen.

 

[kshort]

I'm having similar issues, it appears to only happen on the first cold start; after the codes are cleared the truck runs fine. Battery connections are good, brand new batteries, fluid is good..I've been searching for anything that could be the source but still nothing. Has anyone had any luck or issue with this before? I have come across one other person with this problem and their solution was (as annoying and frustrating as it is) to reset the codes every time they are thrown. It just doesn't make sense that only a few people would have this problem.

 

[Mike L.]

I would replace the pressure switch manifold and internal harness. You may also have a bad internal mode switch. I believe the TCM is not getting feed back which gear the Allison is in.