Diesel Place banner
1 - 20 of 23 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter · #1 ·
Hi Guys,


2015 GMC 2500 Duramax w/Allison


I spoke to my tuner and he had suggested to replace the stock Transmission solenoid with a new solenoid #29541895 to increase line pressure before he does transmission tuning.


Has anybody done this and opinions?


Also does anybody sell a kit to do this? Im thinking I would need obviously the new solenoid, pan gasket, filter and oil. I have never done anything like this before so if im forgetting anything please advise.


Thank you
 

·
Registered
Joined
·
362 Posts
Pan gasket is reusable, and if you remove the drain plug and drain into a suitable clean container, you should be able to reuse the fluid if you want to as well. When the pan comes down after draining there's usually about 1L left in the pan. Solenoid replacement is fairly easy, remove retainer, remove solenoid. The filter might be in the way, it's a friction fit into its bore, sometimes it will almost fall out once the pan is off. If you do decide to replace the filter, your parts department might tell you there's two designs, I constantly have that problem with my one partsmen at work, I always go to get the filter he has picked for me and have to tell him "go get the 'other one' "
 

·
Registered
Joined
·
362 Posts
If your tuner is telling you to it's probably for a reason. I'm a dealer tech so we don't do any work with aftermarket stuff, so honestly I really don't know.
 

·
Registered
Joined
·
197 Posts
I read somewhere that the current trans doesn't have the same pressures as the older ones. Putting more power through the trans is why he is telling you this. Personally I am a believer in keeping things stock, unless you start to have major issues and warranty isn't working for you anymore. Once you start changing things out and programming your warranty is gone. If you start changing things you're on the hook for the bill.
 

·
Registered
Joined
·
5,235 Posts
2015 GMC 2500 Duramax w/Allison

I spoke to my tuner and he had suggested to replace the stock Transmission solenoid with a new solenoid #29541895 to increase line pressure before he does transmission tuning.

Has anybody done this and opinions?
There's nothing special about this valve.
It's in every Allison from 06 six speed to present.
GM Part :29541895 PRESSURE CONTROL SOLENOID(INCLUDES 43)(PIECES 1)
Original Equipment Automatic Transmission Pressure Control Solenoids
 

·
Registered
Joined
·
5,235 Posts

·
Bac To The Future
Joined
·
23,008 Posts
IIRC, there was talk about using a "dummy solenoid" in the LML trans.

I had been reading this thread concerning it: LML Dynoed LML - Duramax Diesels Forum

Hopefully MikeL will see this thread and give you some input on what to do.
 

·
Registered
Joined
·
955 Posts
I had my trans service done by Mike L. at his shop, Inglewood Transmission. I asked about what I could to to prolong my trans as I'm running a 150 hp tune in my truck. He said the problem is the way the trans was designed is that it doesn't hold the line pressure due to being made to lessen all resistance to improve fuel economy, but he had a fix for that. He installed a dummy solenoid that would keep the line pressures up, but said that the trans would run a little bit warmer. My temps went up from 140* in stop and go traffic up to 180*, but once I start going again it drops down to about 140*-150*. I called and told him about it and he said as long as it doesn't get too high into the 200's I should be okay. I run an Edge Insight and one of the gauges shown is the trans temp so I don't have to scroll through my DIC to find it all the time.

Mike knows his stuff!
 

·
Registered
Joined
·
5,235 Posts
This is one person that Mike L helped out.
"I did have Mike L at Inglewood Trans install a dummy solenoid in my trans when I did a service. That will keep extra pressure on the clutches, but it will raise the trans temp. I pulled my 7000 lb boat through the desert and the trans never passed 185* and that was in stop and go traffic, once I got on the highway it dropped to 145*"

Could ask Mike L. About his Black box.
Quote from Mike L.
"The box is installed from the outside and connects directly into the TCM"

"The black box is a pressure riser and will allow the Allison to make its maximum pressure ( 250 psi ) full time. It will hurt mileage a bit and cause the Alli to run 15/20 deg hotter temps. With good clutches, the 250 psi from the box would hold 500+ hp. The problem is the stock LML clutches will not. The LML converter is a very stout converter except for the two sided clutch which will start failing at 800 lb tq"
 
  • Like
Reactions: navybuff

·
Registered
Joined
·
11 Posts
Discussion Starter · #13 ·
HI Guys,


From what im gathering the solenoid valve is there only to satisfy the control module and not throw a code and then the tuner can control line pressure.


If you have PPEI do the tranny tune they can control the pressures without replacing the solenoid. Again this is my understanding and not certain of the information
 

·
Gone but not forgotten member!
Joined
·
14,325 Posts
It's not a dummy valve. What we are doing is unplugging the main mod solenoid which controls line pressure and plugging in another identical solenoid into the harness. This will raise line pressure to a constant 250 psi and satisfy the TCM which will be firing the dummy solenoid and not set off a CEL.
 

·
Gone but not forgotten member!
Joined
·
14,325 Posts
HI Guys,


From what im gathering the solenoid valve is there only to satisfy the control module and not throw a code and then the tuner can control line pressure.


If you have PPEI do the tranny tune they can control the pressures without replacing the solenoid. Again this is my understanding and not certain of the information

The tuner can not control line pressure. He can defeat the main mod solenoid by shutting it off. The dummy solenoid does the same thing exactly.
So you can choose a 400.00 TCM mod or a 60.00 solenoid. feel rich? Go for it.
 

·
Gone but not forgotten member!
Joined
·
14,325 Posts
If one did this on a stock transmission and stock truck in terms of engine tuning, would it prolong the transmission life or be a waste?

Wouldn't do much of anything for a stock truck. It would increase fuel consumption and run higher trans temps.
This mod is for people that want to run more power and not build the trans. It is a band aid only. In my observations, the TCM will not limp the Alli like it did on the earlier models. What it will do is pull serious power very subtly. You might not even notice it. But if you drag race, you will notice it in your time slips. I have observed a 1 second increase with a stock Alli with a programmer. I have also dropped that 1 second increase with a dummy solenoid. ( temporarily till the clutches burn )
 

·
Registered
Joined
·
102 Posts
Wouldn't do much of anything for a stock truck. It would increase fuel consumption and run higher trans temps.
This mod is for people that want to run more power and not build the trans. It is a band aid only. In my observations, the TCM will not limp the Alli like it did on the earlier models. What it will do is pull serious power very subtly. You might not even notice it. But if you drag race, you will notice it in your time slips. I have observed a 1 second increase with a stock Alli with a programmer. I have also dropped that 1 second increase with a dummy solenoid. ( temporarily till the clutches burn )
Thank you for taking the time to reply mike. I was thinking of dropping the pain for an internal filter change and thought if this helped I could do it at the same time. Doesn't really seem worth it, I will think about it.
 

·
Registered
Joined
·
906 Posts
Anyone have a pic of how to do this soleniod mod?
 

·
Registered
Joined
·
102 Posts
Sounds like you disconnect the stock one and plug into the spare to the connector to prevent a code and pressure drop, but I am not sure.

Sent from my SM-N910V using Tapatalk
 
1 - 20 of 23 Posts
Top