G56 Clutch Interlock/Safety Switch Override

Today I spent a little time on Marge the Barge, the old trusty 2010 Dodge 3500. On most days I love having the manual transmission. Mated to a tuned 6.7L Cummins turbodiesel by a Valair organic dual disk, the G56 6-speed manual is a ton (pun intended) of fun to drive. There are times when having a manual transmission isn't the best. Think sitting in traffic. Or recovering from a fractured left femur.

I haven't driven or even started Marge since January due to my injured leg. To start her without sitting in the drivers seat requires depressing the clutch with my left hand while hitting the ignition with my right. Even with the slave cylinder the clutch takes a bit of effort to depress. All this adds up to an awkward experience. Today we're going to fix that.

The interlock switch located on the clutch pedal is a very simple, two wire setup. With the clutch engaged (pedal up) the circuit is open and the truck will not start. This keeps someone from accidentally starting the truck while in gear. Once the torquey Cummins gets going it isn't stopping for much. Makes sense to have the safety switch in place. Conversely, when you depress the pedal far enough to allow the contacts to touch and the circuit is closed and the truck can now be safely started.

Today I'm installing a momentary switch that will allow the truck to start without depressing the pedal. There are many reasons why you may want to start the truck this way, for me the greatest advantage is being able to knock it into neutral, push the button and start the truck. By using a momentary switch the truck still won't start accidentally. As an added deterrent I'm going to position the switch where it won't be accidentally depressed. A person would need to make a conscience effort   to bypass the clutch interlock.

Here's the mod:

Step 1: Remove the two (2) screws holding the lower dash cover in place. Gently, but firmly pull from the bottom to disengage the retaining clips and completely remove the cover.

Step 2: Remove the interlock switch from the clutch rod by pinching the clips on the white panel and sliding backwards. Push the switch up and off of the rod. Unclip the pigtail by sliding the red tab back then depressing the retaining clip.

Step 3: Tap new leads into the two existing wires on the switch. For this I used ~2 feet of 18 AWG wire for each. The new leads were soldered onto the factory wires. I purposely left the wires long as they will be cut to the appropriate size after routing.

Step 3: Reinstall the switch on the clutch rod.

Step 4: Install the switch in the dash panel.

I picked up a simple momentary switch from the local autoparts store. Simple, push button that is normal open design.

To mount this specific switch I had to drill a 3/4" hole in the lower dash cover. After making the initial hole I found that that particular area of the cover was actually 2 layers thick. Turns out that it is just as thick as the switch is long. This is a problem since I can't run the nut onto the threads to hold the switch in place. Two options here: 1) drill out a second, larger hole in the rear to countersink the nut or 2) use some epoxy to permanently mount the switch. I'm keeping this truck forever and now there is a big hole in the dash cover so I'm OK with the permanent mount solution. Decision made I fit the switch, mixed the epoxy, and filled the space around the switch. I let this sit about an hour then cut the wires to size. Strip the ends, fit into the switch, and clamp down the screws.

Step 5: Replace the lower dash panel and enjoy!