2008 Mazda 3 - 2.0L Standard Trans Ignition problem

Tyler wrote: Is the PCM still accessible? I'm tempted to suggest going there next.

Rather than digging around for the Neutral Switch and the Clutch Pedal Position Switch, I figure it's easier to find the signal wires at the PCM connector and check their operation that way.

Unfortunately, the OE diagrams don't point out pin locations, or have all the PCM pins in numerical order so we could figure out color sequencing. You're looking for a black/orange wire for the Neutral Switch, and a black/yelllow wire for the Clutch Pedal Position Switch. I know, that doesn't narrow it down much. :silly: I can definitely say they're in the same PCM connector (of the two).

They're both going to be pull down switches, so we're looking for 5V or 12V with the switches open, and 0V with them closed. You may have to work the shifter to make the Neutral Switch work. If both change states while working the clutch or shifter, then I'm gonna figure they're working correctly.

Sorry for taking so long to get back to you, I was away at a tradeshow for work and then my wife and I took a weekend vacation to Niagara on the Lake and then I was busy with work and finally got to test out these latest suggestions.

So, we tested the Neutral Switch and the Clutch Switch against B+ and received a reading of 12V for both in both open and closed, i.e. when cranking and not.

I was wondering, because the car was in a collision, could the problem be a positive short off of the alternator? If so, how could we test for this?

Thanks again for all of your knowledge and assistance!
Jon

No worries about the delay!

So, we tested the Neutral Switch and the Clutch Switch against B+ and received a reading of 12V for both in both open and closed, i.e. when cranking and not.

Sorry, but I'm not quite sure I understand these results? Was this done with a DMM or test light? If you wouldn't mind, try a DMM with the ground connected to B-, probing the neutral switch and clutch switch. KOEO, work the shifter and clutch without cranking, and tell me what you see.

I'm thinking that the neutral switch isn't going to be a cranking input, but the clutch switch might be. If you see 12V on the clutch switch circuit with the clutch pedal all the way down, then I'd suggest a bypass test. Connect a test light to B- and probe the clutch switch pin, then try cranking again. Use the DMM to confirm 0V on that circuit if needed. If it now cranks, we're on the right track. If not, we'll need to go in another direction.

Sorry that I went away for a while again. Winter hit and I had to clean out my garage to move the car in.

I tested the Clutch with a DMM and was getting mV with the clutch engaged and disengaged.
The Neutral test gave me 12V when in gear and mV when out of gear.

Does this mean that the clutch sensor is the issue?

No worries, sorry for taking awhile to get back to you! :blush:

So the neutral switch works, but the clutch switch would seem to be stuck closed or shorted to ground. There's definitely no switching going on there.

Would you mind testing that same clutch switch pin at the PCM with a test light? Light connected to B+, see if the bulb lights. That'll confirm a stuck switch or short to ground.

If the bulb lights, then you've got a couple options. My first suggestion would be to cut the black/yellow wire for the clutch switch somewhere close to the PCM, but easily repairable. Then, either try to crank the engine, or measure voltage on the PCM side of the cut. Should be 12-ish volts. If the engine now cranks, we're onto something.

The other option would be to track down this clutch switch and do more testing there. I have no resources to tell me where this switch lives, exactly. Have a closer look around the clutch pedal for any switches that might be hiding.

So I couldn't get the trouble light to work on the B+ to 1D (clutch switch), so I tried cutting the wire anyway. Then I re-tested B- to the clutch switch KOEO and I got 11.8 V on the DMM when the clutch was not engaged and random mV when engaged. So this is not the issue....

What should we check next?

I tried jumping the clutch position sensor. The light comes on with the key off between B- and 1D. Then when the key is on the light goes off whether the clutch position sensor is bridged or not. Also, the engine does not crank whether 1D is cut or not... is this a short or what could it be?

Hey Tyler,

I'm not sure if you're still around, as this is an old thread, but I have a similar issue to the OP here and I'm stumped and I wonder if you'd be able to help me figure this out.

Thanks,
Charlie