CEL P0704/P0507 Knowledge Capture
These forums were helpful to me in diagnosing performance issues so, thank you! Thought I'd capture the knowledge I gained for posterity...
2007 Mazda 3 2.3L Manual Transmission
CEL: On
OBD-II Trouble Codes: P0102, P0507, P0704
Symptoms:
Bad idle, bucking/hesitation when accelerating after shift, clutch-in when approaching a stop light resulted in stalling, RPM rise when putting the car in gear while stopped with clutch-in, decreased fuel economy.
P0102 fix: Second time with this code due to a broken wire in the MAF harness, about an inch back from the connector. Original fix was a crimp job. Addressed with a proper soldered fix of the wire, cleaned MAF sensor, then cleared trouble codes. Immediately running smoother; no longer any stalls, rough idling, or jumpy shifts.
P0507 & P0704: These two CELs came back after a couple of drive cycles. Still noticing rev changes when shifting into gear while stopped w/ clutch-in.
- Removed and Cleaned throttle body per Mazda Service Bulletin SB01-007-09-2069 titled "UNSTABLE IDLING/ENGINE STALLS JUST AFTER STOPPING" (Ask Jeeves, he'll show you where you can download a pdf). Resulted in noticeable improvement of rpms at idle and shifts (smoother). Did not clear CEL and codes did not clear on their own. Gas mileage still has not improved (which surprised me).
- Removed and installed new OEM clutch switch P/N BP4K-66-49YA per (or close enough to)
service manual procedure . I removed the switch w/ a turn and pull first, then removed the wiring connector by pressing a screwdriver into the connector and pushing it out. It's too hard to reach otherwise. Removal and install took about 60 seconds. Immediately there was improvement to smoothness of idle and when placing the car in gear w/ clutch-in.
Information on the switch's name/part# and what switch is responsible is a bit confusing, because there are two switches in the clutch pedal assembly. I replaced the lower switch (blue & grey). It is referred to both as a Clutch Position Switch and a Neutral Safety Switch depending where you look. I believe those to be two different things. As far as I can tell this is the CPP. The switch higher up and to the right (black w/ white plunger) is the safety switch, I think. They oppose each other, one is always pressed while the clutch is engaged and the other is depressed when the clutch disengaged. Either way, search the part number or pick one that looks like the image in the repair manual; that's the one I went with. For about $12 bucks shipped, I got mine from a Mazda dealer on Ebay.
When I removed the original switch it was obvious that mechanically it had failed. The plunger should smoothly travel out when the clutch pedal is depressed. Mine was clunky, with shortened and loose travel. I could also hear pieces moving around when I shook the housing. There are two springs inside the switch that produce the tension causing the plunger to travel, moving the copper plates on/off the terminals, which then opens or closes the circuit. I took the switch apart and the larger of the two springs was completely destroyed (see attached images). I haven't had enough drive cycles yet to determine if this resolved everything, but if I don't reply, assume that all is right in the world.