Hey 6MT owners! Do any of you have problems with your clutch position switch? This is a small plunger-style switch attached to your clutch pedal. When the pedal is depressed, the little plunger on the switch is pushed in and the ECU knows the clutch is engaged. It's a safety feature when starting the car, so you don't accidentally start the car while in gear.

Starting about two+ years ago, my car was experiencing a random non-start scenario. Press the ignition button, and it would just click once and the dash "clutch" warning would come up. Or sometimes it would behave as if I weren't pressing the clutch pedal at all, and simply engage the dash electronics, as if I wanted to use the radio without starting the car.

Took me a long time to realize what the problem was. I even went so far as to replace my battery, thinking this was symptomatic of a weak battery. Finally, my local Infiniti service department suggested it could be this switch, so I spent $20 and installed it myself. Problem solved.

Yay!

Fast forward to this summer, and it's starting again (or "not starting", LOL.) Same exact behavior. So I just ordered a replacement switch through RockAuto.com, and will swap it in as soon as it arrives. So here are my questions: Anybody else have this problem? And what do you think is going on?

My go-to suspicion is the RJM pedal. It's possible the RJM pedal is applying too much stress to this little plastic switch, or it's doing so at a slightly awkward angle.

 

i had this problem in my old '04 G35 6MT sedan. random no starts would occur off and on over a long period, getting worse over time. after interweb searches, i narrowed the search to the clutch switch, looks identical to your photo. it was a known issue in the G35 so i suppose the G37 uses a similar setup.

i removed the switch and jumped the connection until i replaced the switch which was ~$20 at the dealer. i wasn't worried about in-gear starts since i always leave my cars in neutral with the handbrake on.

it is odd that you are seeing a likely 2nd failure. i have the RJM and, knock on wood, no switch issues yet.

 

Try adjusting the switch so that it's not bottoming fully out when the pedal is to the floor. As I understand it, this might be putting additional strain on it and eventual failure.

Also, every MT driver should know what it is, where it is, and how to bypass when in the field (unless you like calling a tow truck).

 

Good advice, jsolo. will do.

How do you bypass?

 

This was my first thought reading this. Doesn't this issue roughly coincide with when you installed the RJM pedal?



This. As you know from the install, getting this adjusted is part of the instructions. I agree, maybe you're putting a little too much strain on the plunger.

 

I'd have to check my records, but off the top of my head it feels like 10k miles from the RJM install, and then another 10k or so since the last new switch. Give or take.

So yeah, I'm thinking the way I installed the switch on the RJM (both times) is causing it to wear out. Granted, this is all conjecture, and I've no guarantee the next replacement switch resolves the problem again. Guess time will tell, and I'll be sure to update this thread. Might be useful to someone who's trying to diagnose intermittent start failures.

 

A thin paper clip into the connector should do the job. Be careful the paperclip doesn't touch anything. I'm not sure if it will throw a code once the car is started. Technically the pedal can't be at the top and bottom at the same time. Still, a code is better than not being able to start the car IMO.

 

If there were an accessible push-button switch I could hold down with my left hand while my right hand was pressing the ingition switch and the clutch pedal was depressed, essentially moving the switch from the pedal to my hand...



That would be a crazy hack, LOL. Damn fine theft deterrent, too. Probably illegal in some states, or at the very least an inspection fail.

 

I think this is easily doable. You'd have to hack into the switch wiring and install another momentary push button type switch in series. If you really want to get all fancy, a circuit (so it doesn't interfere with other functions) could be designed such that both brake and clutch is required to start the car.

 

I think a manual is pretty good theft deterrent as is

 

I looked it up this morning. RJM was installed at 25k miles, and the original switch started to fail at 31K miles, replaced 2k miles later once I finally figured out it was the clutch position sensor. That second switch started to fail at 39K miles.

So that makes a 6000 mile interval between install of the RJM and failure of the first switch, and a 6000 mile interval between the second switch and the current failure situation. (Assuming it's the switch that's at fault here.)

FWIW. Heck of a coincidence.

 

I'd back out that set screw (or whatever the technical term is) a little at a time, until the car wont start, then tighten it a wee-little bit.

 

Yep. That's the plan. I'm going to install the new switch with an eye towards making sure the little plunger isn't pushed all the way down.

The new switch arrived today, so I'll be doing this soon. (Wow, RockAuto.com is FAST!) Although I'm not really looking forward to twisting my old bones all around in the footwell.

 

Have fun with that. At this point, you're practically an expert

 

@Lego_Maniac I think the technical name is lock nut.

@Rochester It might be easier to remove the dash panel (the one with the switch block) for better access?