Help: LMM intermittent tow/haul

[RC Smith]

My LMM will sometimes go into tow/haul , sometimes it wont. When I hit the button the dash light will always turn on and off as it should. The truck will go in and out of tow haul while driving, the light stays on.

I have pulled up the tcm data on my scanner while driving and tow haul will go from active to inactive and back and forth by itself, the dash light will stay on.

I think there is a bad wire somewhere because it is intermittent, but this function looks to be on the hs lan network but it still shifts perfect so the network is fine??

 

[Mike L.]

You need a new shift lever. They cost between 75-100 and takes about 30 minutes to install. Dealer item.

 

[Woodster]

Mike nailed it.

Hope this helps.

https://www.youtube.com/watch?v=FtXPwPrXhFc

 

[Mike L.]

Mike nailed it.

Hope this helps.

https://www.youtube.com/watch?v=FtXPwPrXhFc

Wrong video.

 

[RC Smith]

since the switch pulls the bcm wire to ground when pressed, I turned on tow haul and then unplugged the shifter under the dash to eliminate the wiring in the shifter. The light stays on and it still goes in and out of t/h.
Is there anything in the ecm or tcm that can disable the tow haul?

 

[2004LB7]

How do you know it is going in and out of T/H if the light stays on?

 

[RC Smith]

It will come out of tow haul and unlock the converter and shift up and then shift down and lock it again when it goes back into th. On the scanner under the tcm data it will show tow haul active then inactive.

 

[THEFERMANATOR]

What is your trans temp when it does it? If it sees a disruption in the trans temp signal, it can change shift schedules. Also look to see if maybe it is triggering 4 low by chance. And I would check to see if you have any signs of water in the drivers side kick panel area. I had an LMM doing weird stuff like this and it ended up being corrosion in one of the plugs in the kick panel area from water leaking in. There was a tsb for it.

 

[RC Smith]

Just drove it watching the t/h and 4 low on the scanner. T/h switched to inactive while 4 low stayed inactive, I was in 2 wd. The t/h going on and off seems somewhat related to going up or down hills, the engine being under load or decelerating. There is some moisture under the panel inside the drivers door, I will check the connections for corrosion.

 

[RC Smith]

All the connectors and wiring look good. I went through the tcm and ecm data that I could watch and I think there is some parameter kicking the truck out oh t/h. If I put it in drive holding the brakes and get on the throttle about 1/4 down it will deactivate t/h, and go back into t/h when I let off the throttle.

Does anyone know the parameters for allowing the truck to be in t/h?
I have an autocal, is this something data logging could help with?