Allison 5sp: Range Shift Inhibited....

[tpijeep]

I have been fighting this for over a month.

I got the famous Range Shift Inhibited with blinking indicator and truck will only move on flat ground in Low range for 6 seconds at a time. If you go from Neutral to Drive you can hear the engine load up and within a few seconds the load goes away.

I have changed the Ignition Switch NSBU switch, checked every connection on the truck, added extra ground wires and cleaned every other ground.

I was getting a series of Class 2 data link codes but not a single transmission code except for the U1000 that the PCM is also throwing.

I put it up on the lift and it will go into gear and will spin up to about 40 mph but does not upshift and if you put it back on the ground it will pull but its in either 2nd or 3rd gear, if you go back to neutral its back to Range Shift Inhibited

I ran the codes after doing this test and got a P0731 Incorrect 1st ratio, I assume this is because its Commanding 1st and its getting 2nd or 3rd. I also got a P0746 Pressure Control Solenoid A stuck off.

This is the first time any TCM related codes have come up during the month long ordeal.

Is all this caused by the Stuck Solenoid A?

Sig Line not showing up "PPE Stage 5 kit, Precision ML convertor, DSP5 tune by Duramax Tuner, AirDog II"

 

[IOWA LLY]

Sounds like a stuck valve.

What does it do in reverse?

Have you monitored the speed sensors to see what they are doing when it acts up?

Sent from my SCH-I535 using Tapatalk 2

 

[Mike L.]

Pull the pan and check the sump filter.

 

[tpijeep]

Pull the pan and check the sump filter.

Figured that is where I was gonna have to go, FWIW its a deep sump with filter loc. I'll get it pulled and report back !


In reverse you can tell its trying to move but its much less then in drive, the speedo works fine so I assume the sensor at the transfer case is okay.

 

[tpijeep]

I just got my truck on the lift been hell month around here.

Pulled the pan and there are no debris in pan and the sump filter is clean, pickup tube is not cracked. I know it was sealing fine because when I pulled the filter out of the case a surprise quart of fluid hit my employee in the face.!

And the hunt continues.......

 

[tpijeep]

Please tell me that it is just this simple.

I removed Trim Solenoid B with the valve, in the end of the valve is a spring about the size of one in a ball point pen and a small check valve. I took out Trim Solenoid A and there was not ball and spring. I started to dig around in the valve body and found the ball and 2 spring halves in the passage behind Valve A. Its is marked with the tip of the pen in the pictures below.

 

[Mike L.]

You found it. :thumb:

 

[tpijeep]

You found it. :thumb:

Hahahahaha! Dang stupid stuff! Now the question is can I just replace it with the cool spring out of my ball point pen!

One last question, My service manual doesn't show the the large spring near the Trim Solenoid A in the book but I know it came out of there. Is this the correct layout for the "A" valve?

Thanks, I'm finally gonna have a relaxing weekend!

 

[durallymax]

Hahahahaha! Dang stupid stuff! Now the question is can I just replace it with the cool spring out of my ball point pen!

One last question, My service manual doesn't show the the large spring near the Trim Solenoid A in the book but I know it came out of there. Is this the correct layout for the "A" valve?

Thanks, I'm finally gonna have a relaxing weekend!

Yes that is correct layout for trim valve A

 

[tpijeep]

Good deal.... I found a stainless spring out a pen that was the same size and just trimmed it down, i can't see why that wouldn't work.

Like I have seen posted many times before, its the simplest things that cause the weirdest headaches....... crossing my fingers that this works....

 

[Mike L.]

The spring you are going to use is not heat treated and may cause you problems. It can burn some clutches. I don't recommend it.

 

[tpijeep]

Well if I have learned one thing from reading this site it is that is Mike L says not to do something then don't when it comes to the Ally.

Oh well I really wanted to get it back under its own power this weekend but I guess I will wait.

Where can I find these parts quickly, I am about 1 hour from PATC transmissions, would this be part of a small parts kit or is it going to be a used part I am looking for?

 

[tpijeep]

I just pulled my head out of my ass and realized that these ball springs were part of the shift kit that was installed when I built the transmission.

Are the Trim Valves and check balls and springs the same in the 6 speeds as the 5 speeds? Can I buy the much cheaper kit for the 6 speeds and just use the trim valves since my tranny already has the pump upgrades?

 

[Mike L.]

All you need is a Transgo jr. Buy one on flea bay and steal what you need from the kit.

 

[durallymax]

I just pulled my head out of my ass and realized that these ball springs were part of the shift kit that was installed when I built the transmission.

Are the Trim Valves and check balls and springs the same in the 6 speeds as the 5 speeds? Can I buy the much cheaper kit for the 6 speeds and just use the trim valves since my tranny already has the pump upgrades?

To clarify what mike said, yes the parts out of Transgo JR are same for 01-10 trucks. JR just includes the trim valve mods for less than 100.

 

[tpijeep]

Thanks for the help!

 

[tpijeep]

Well that was the problem! Shifts clean and crisp.

Now I just have to reloom all the wires, put half the truck back together, reinstall every aftermarket electrical accessory I removed during troubleshooting and try and find my sanity!