Can you eliminate the OD switch?

graycenphil · **Posted:** Fri Apr 24, 2020 2:51 pm

I pretty much never use the OD switch in my ‘06 CRD. That is, I always have it switched to allow overdrive.

My daughter is now driving the car, and She will definitely not turn OD off, except by accident, in which case she might drive all day with it turned off.

Is there any fairly simple way to disengage the switch, so she can’t hit it inadvertently?

Thanks.

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

graycenphil wrote:

I pretty much never use the OD switch in my ‘06 CRD. That is, I always have it switched to allow overdrive.

My daughter is now driving the car, and She will definitely not turn OD off, except by accident, in which case she might drive all day with it turned off.

Is there any fairly simple way to disengage the switch, so she can’t hit it inadvertently?

Thanks.

This might not be as simple to do as it sounds at first, but it's probably not totally awful either.

Bear in mind that the overdrive switch is a momentary button - each press signals (probably) the TCM to either turn overdrive on or off depending on the state that it's in when you press it. It's not a like a light switch, where there are unique positions for on and off.

As it turns out, the switch is apparently considered part of the shifter assembly (read: shift knob) per both the FSM and parts fiche. This leaves a few options to explore; all of them start the same way, except for the last one:

Remove the shift knob and separate the overdrive switch from it

This leaves you with a few options:

If the switch wiring can be separated from the switch without turning off overdrive, just remove them, insulate the ends, and leave the switch in place to fill the hole in the shift knob (this assumes only two wires on the switch)
If separating the switch wiring turns overdrive off, splice the wires together, verify that overdrive is restored, and insulate the splice (again, this assumes only two wires on the switch; leave the switch in place to fill the hole)
Remove the switch, separate its button from it, JB Weld the hole in the shift knob, replace switch
Similar to the above idea, epoxy or superglue the button in place to the shift knob (personally wouldn't trust this for the long term)
Point switch out to daughter, explain that the only time she should ever press it is if the 'O/D Off' light on the dash is illuminated

graycenphil · **Posted:** Fri Apr 24, 2020 8:00 pm

Thanks Casm. That all makes sense. Do you know how to get to the switch? Does the top of the shifter (with the button) separate easily to access the wires?

casm · **Joined:** Sun Jan 29, 2006 5:05 pm **Posts:** 694

graycenphil wrote:

Thanks Casm. That all makes sense. Do you know how to get to the switch? Does the top of the shifter (with the button) separate easily to access the wires?

Sorry, no idea - it's not something I've ever had to do. My suggestions were based entirely upon observation, both from how the switch works in our KJ as well as what the FSM and parts fiche had to say / show.

Having said that... It feels like there's one screw at the bottom of the shift knob on the forward-facing side that may be the keystone here. If you move the shift lever into the '1' position, it may be visible. Taking a shot in the dark at it, that screw can likely be removed followed by pulling the shift knob straight up to remove it.

Based on past experience with automatic gearbox shift levers, I'd recommend being prepared for springs if that screw is removed. Someone with more experience than me in this area can comment, but just be careful.

graycenphil · **Posted:** Fri Apr 24, 2020 11:01 pm

Thanks again Casm. Luckily, I’ve currently got lots of time on my hands, nowhere to go and nothinig to do, so maybe I’ll give it a try.

Stay healthy.

layback40 · **Posted:** Sat Apr 25, 2020 8:04 am

You could try gluing a thick plastic washer over the switch button to make it recessed so that she doesnt just knock it.
Maybe she likes the OD off. Didnt the Beach Boys have a song about a girl & a Tbird ? :rockon:

graycenphil · **Posted:** Sat Apr 25, 2020 8:22 am

LOL Layback40. And I liked that song, but that is exactly what I’m trying to avoid.

Interesting idea about the washer - that would allow me to use the switch if I ever did want to.

Thanks.

WWDiesel · **Posted:** Sat Apr 25, 2020 1:42 pm

A suggestion,
Locate the DG (20 ga. Dark Green) wire that goes into the C105 connector @ position 12 that is located near the TCM (Transmission Control Module). See enhanced drawings below:
Cut this wire and connect cut ends to a simple on/off toggle switch and mount the switch in a safe location under the hood.
Be sure and seal all connections real good with heat shrink wrap tubing or liquid tape.

This would allow you to disable the Overdrive lockout switch/circuit with the simple flip of a switch under the hood at your discretion and you could put it back in service anytime you wanted to.

graycenphil · **Posted:** Sat Apr 25, 2020 3:51 pm

Thanks VWdiesel. This forum is the best.

Can you eliminate the OD switch?

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