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I am experiencing symptoms that have led me to track down and diagnose the neutral switch on my 2008 Mazdaspeed3 (6-speed MT/2.3L Turbocharged). These symptoms include:

  • DTCs of P0507 and P0850
  • When starting the car in neutral with foot off clutch, RPMs usually descend from about 1.2k to about 600 over the course of several minutes; currently, it remains high, but drops when the clutch is depressed
  • Coming to a stop in neutral, engine occasionally dies

I've attempted to use online manuals to locate and identify this switch (1, 2), but when I look in the described location (passenger-side behind No.1 engine mount) there are no wires or switches (image).

I did look around and found some potential candidates, though. This image, toward the top of the image, has wires going to two identical-looking objects that resemble the switch I'm looking for (closer view here and here), with the major distinguishing characteristic that one's harness comes in from the side and the other from the top.

I would appreciate anybody who could either confirm/deny one of these switches, or otherwise direct me to the correct location. Furthermore, since the documentation I was following was wrong to this point, I also question whether I can trust the torque specifications provided:

Tightening torque

19.6-29.4 N·m

{2.0-2.9 kgf·m, 14.5-21.6 ft·lbf}

  • I'm looking online at parts. I'm seeing it listed as a "Clutch Pedal Position / Starter Safety Switch" ... that would place it in the cabin at the pedal? Which engine does your car have? I'm seeing three listed. – Pᴀᴜʟsᴛᴇʀ2 Feb 27 '16 at 15:23
  • There is a clutch pedal position switch, which I believe to be an entirely different component. The purpose of the switch I'm interested in is knowing when the transmission is in a neutral state. Edit: As to your question about which motor, on O'Reilly it is listed as "Mazdaspeed -- L4 - 2.3L 2260cc type MZR - MFI GAS DOHC Turbo-charged" – Justin Bell Feb 27 '16 at 15:46
  • 1
    Are you sure you're looking at the right transmission information? I'm seeing the G35M-R as being a 5-speed transmission. I'm seeing the G36M-R as being the 6-speed. That may be where your dilemma lies? – Pᴀᴜʟsᴛᴇʀ2 Feb 27 '16 at 16:35
  • You are probably correct, the documentation I had didn't reference the G36M-R but the differences were significant enough that I was convinced of the same. – Justin Bell Feb 27 '16 at 20:28
  • I believe the OEM part # of the neutral switch is A61117640D and was not identified as a valid part for the popular (Napa, O'Reilly, Advance) local parts stores. This switch seems to be regularly confused with the neutral safety switch for automatic transmissions, in case anybody else encounters similar issues. – Justin Bell Feb 27 '16 at 20:36
2

I ended up diagnosing those connectors by disconnecting them from their respective harnesses and doing continuity tests while they were plugged in. Thankfully, the switch was still working (turns out the problem was a cut harness further up the line, probably the result of a recent trip to the mechanic).

The port at the bottom of the transmission is the neutral switch, which is closed when the transmission is in neutral and open when in gear. The top switch ended up registering as closed when the transmission was shifted into reverse, and open at all other times.

  • I'm glad you figured it out! Nasty mechanics ... I try to stay away from them when I can :o) – Pᴀᴜʟsᴛᴇʀ2 Feb 27 '16 at 20:47

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