does anyone know if you can wire in a switch for Tow/Haul mode in a 411 conversion ?

I don't think so. The Tow/Haul mode switch sends a momentary signal to the BCM and the BCM sends serial data to the PCM (As I understand it) Since our trucks don't have a BCM, I don't think it could work.

Jeff

Jeff is right if you have a completely stock PCM. BUT if you have a EFI live Custom Operating system
you can use a single wire into the PCM.

I have HPTuners, so I guess the COS is not an option, however in HPTuners there is a selection dropdown for the input for the performance shift parameters, so I dont think it's contained to just a BCM function

Orange SS you are correct, I was thinking of the Valet switch.
EFILive has the same option for a stock truck. Once you make the change in the tune
you can connect a momentary grounding switch to C1 pin 71.
The Data Bus is the factory setting.

L31Sleeper wrote:

Orange SS you are correct, I was thinking of the Valet switch.
EFILive has the same option for a stock truck. Once you make the change in the tune
you can connect a momentary grounding switch to C1 pin 71.
The Data Bus is the factory setting.

momentary ground ? how does the system deactivate ?

Actually you would use a toggle switch to give that pin a ground if using a Custom Operating System. At least that is how EFILive does it.

Lextech wrote:

Actually you would use a toggle switch to give that pin a ground if using a Custom Operating System. At least that is how EFILive does it.

so I cant just add a toggle switch to ground and have a Tow/Haul mode ?

The problem with this is there's no indicator to show whether you're in tow/haul mode or normal mode. It's a momentary ground that toggles between the two modes, and since the L31 trucks don't have a light in the instrument cluster, there's no way to see what mode you're in. The trucks that have this from the factory illuminate the light in the cluster when the IPC module receives a message over the class 2 bus from the PCM saying that tow/haul mode has been turned on.

PSWired wrote:

The problem with this is there's no indicator to show whether you're in tow/haul mode or normal mode. It's a momentary ground that toggles between the two modes, and since the L31 trucks don't have a light in the instrument cluster, there's no way to see what mode you're in. The trucks that have this from the factory illuminate the light in the cluster when the IPC module receives a message over the class 2 bus from the PCM saying that tow/haul mode has been turned on.

so it is a momentary ground ? I could use a latching relay to a dash mounted light

orange ss wrote:

PSWired wrote:

The problem with this is there's no indicator to show whether you're in tow/haul mode or normal mode. It's a momentary ground that toggles between the two modes, and since the L31 trucks don't have a light in the instrument cluster, there's no way to see what mode you're in. The trucks that have this from the factory illuminate the light in the cluster when the IPC module receives a message over the class 2 bus from the PCM saying that tow/haul mode has been turned on.

so it is a momentary ground ? I could use a latching relay to a dash mounted light

Yup, momentary ground. You could get creative with latching relays but you'll also need your circuit to reset to off when the ignition is switched off.

Sorry for the confusion I caused.

The Custom Operating system function valet / N2O mode uses a toggle or other constant switch.
via C2 pin 56

The Tow / Haul mode can be set to use a momentary grounding switch instead of the Data Bus.
via C1 pin 71

PSWired is right you would have a difficult time tracking weather the mode is enabled or not.
a latching relay would let you know the function has been turned on but I think un-latching
the relay with the same momentary switch would be tough. You might have better luck with
transistors.

That would work but you would want the constant 12v to be ignition 12v that way the whole thing
shuts off when you turn the key off.

The momentary switches on the 99+ programs like the foglights and tow/haul are reset to factory default when the ignition is switched off, so if there were a way to toggle the light on and off with a momentary signal, that would automatically turn the light off when the ignition switch is turned off, would be all that is needed. No matter what, base would be off when you start the engine.

Speeder wrote:

The momentary switches on the 99+ programs like the foglights and tow/haul are reset to factory default when the ignition is switched off, so if there were a way to toggle the light on and off with a momentary signal, that would automatically turn the light off when the ignition switch is turned off, would be all that is needed. No matter what, base would be off when you start the engine.

The relay system shown is not connected to the PCM. The momentary switch would send the signal to the relay and
the PCM but the PCM would have no "control" over the relay. If you had constant power the way that diagram shows
the light would remain on when the IGN was turned off. When you restart the truck the light would remain on but
the PCM would have gone back to Normal mode.