No gear indication on the PRNDL, flashing O/D off light, and CEL. Speedometer stays at zero. Can't shift out of park when depressing the brake pedal; you instead have to press the release on the top of the steering column. The car is drivable but in "limp mode." It shifts really early, so it's weak, but going up a hill if you put the pedal to the floor it'll downshift. The codes:
P0706 - Neutral safety switch (or transmission range sensor) circuit problem
P0500 - Vehicle Speed Sensor problem
To my mind these two go hand in hand. The computer doesn't know what gear the transy is in so it's confused when it's sensing speed. I bought a new NSS / TRS from RockAuto and could not get the old one out due to the weird positioning of the wire, but I plugged the new one in to the wiring harness just to see if it would register what gear I'm in. It won't. I took it to my local mechanic, he diagnosed and installed the NSS/TRS I had bought, but problems remained. He told me to take to a transmission shop. Transmission shop guy did some diagnostic and seems pretty certain that mechanically the transy is fine (thank God) but the problem is electrical and he doesn't really do electrical...he has his hands full on just repairing the innards of transmissions.
So the question: is it more likely I have bad NSS/TRS from RockAuto and need another? Or that one of my speed sensors is bad?
2006 Mazda MPV
Sounds like a fault in the wiring harness going to the transmission. Make sure it's not damaged, and connector is clean and tight.
I would get the OEM part to make sure if the aftermarket part is junk or not.
Thanks for the responses. I am over my head with getting into the wiring harness. I will visually search for damage, but I have a shop that I'll take it to Tuesday morning, and their guys should be able to hunt and find where the problem is.
Well, to give everyone closure: turns out I'm paying a big stupid tax for not hunting hard enough myself. My problem: I installed an aftermarket backup camera, one with a wire that connects to the reverse lights, so that it turns the screen on when you go into reverse. That camera was causing a short circuit, blowing the number 22 fuse for the backup lights and confusing the whole transmission and ECU apparently. Such a freakin' simple thing, if only I had hunted down that backup light fuse...I would've found it was blown and put 2 and 2 together, disconnected the backup cam line, and solve the problem for a couple bucks. As it stands, I'm in it for $580 worth of diagnostics because the shop started hunting the problem from the brake pedal shift-lock switch. The aftermarket backup cam should have been the obvious place to start for me, because I'm the guy who put it there. I don't fault the shop for not starting there, they were starting with the assumption that nothing had changed about the car's electrical system.
I just have to keep reminding myself of how much money I have saved over the years by doing virtually all my own car repair work.