tow haul engages without notice at highway speed have to push button to disengage.

 

Does the light in the instrument cluster come on as well? The reason I ask- if it's the switch or something in the PCM, the light should turn on in the cluster. If not, then the problem is in the transmission.

If you can find where the tow haul plug connects to the ECM (I think it connects there), if the resistance is above 5 ohms, you're good. It should only be below 5 ohms when the button is pressed.

 

I will see what I can find out it's my daughters 04.5.

 

Also ask her if she still has the trim ring around the button on the shifter. They come off sometimes and the button will rattle around and engage the function. I've got the dealer manual for the 04, so let me know if you need more info, just shoot me a PM.

 

Had same problem two years ago. Nobody could figure it out. Ended up being the tow/haul wire down by the motor. There is approx 59 wires in that bundle of wires and the tow haul wire had a nick in it. Had to happen from the factory and took a few years to degrade the wire

 

U mean at the ECM do u have a description of wire.

 

Yes by the ECM. The bad spot on my wire was only a couple of inches up from the ECM so I was lucky. Off the top of my head I believe the tow haul wire was dark green

 

Thanks

 

One of the wires is dark green, the other is light blue and black.

Symptom: O/D TOW /HAUL SWITCH
POSSIBLE CAUSES
O/D TOW/HAUL OFF SWITCH SENSE CIRCUIT SHORTED TO GROUND
O/D TOW/HAUL SWITCH
ECM - O/D TOW/HAUL SWITCH
TEST ACTION APPLICABILITY
1 Turn the ignition off.
Disconnect the ECM harness connector.
Disconnect the O/D Tow/Haul switch harness connector.
Measure the resistance between ground and the O/D Tow/Haul switch sense circuit in the ECM harness connector.
Is the resistance below 5.0 ohms?
Yes Repair the O/D OFF switch sense circuit for a short to ground.
No Go To 2
2 Turn the ignition off.
Disconnect the ECM harness connector.
Measure the resistance between ground and the O/D Tow/Haul switch sense circuit in the ECM C2 harness connector.
Press the O/D Tow/Haul switch button.
Does the resistance change from above 5.0 ohms to below 5.0 ohms while pressing the O/D Tow/Haul Switch?
Yes Go To 3
No Replace the O/D Tow/Haul switch in accordance with the Service
Information.
3 If there are no possible causes remaining, view repair.
Replace and program the Engine Control Module per the Service
Information.