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So I own a '04 Mazda 3, 2.3L engine, & no matter what I have done for it lately. Nothing has worked. It keeps coming up with the code P0762, which is Solenoid C Stuck On. CEL is on along with the AT light. I replaced the solenoid C & transmission fluid, cleared the code & still.. Having the same problem. Going to be checking today to see if it could possibly be a wiring issue. Keep you all posted about it. I just need a solid solution to this before something worse happens to it..
 

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So I own a '04 Mazda 3, 2.3L engine, & no matter what I have done for it lately. Nothing has worked. It keeps coming up with the code P0762, which is Solenoid C Stuck On. CEL is on along with the AT light. I replaced the solenoid C & transmission fluid, cleared the code & still.. Having the same problem. Going to be checking today to see if it could possibly be a wiring issue. Keep you all posted about it. I just need a solid solution to this before something worse happens to it..
Transmission control modules are know to be a common issue on these cars. If the wiring checks out then it's probably the module.
 

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Thank you for replying to this!! I didn't get around to checking if it was a wire problem today (because honestly, I wouldn't even know where to start. I hate wiring, 1 of my weak points 😕) I been reading up on that lately it being the TCM, I'm hoping that's the major cause for this. Won't know until after work/checking the wiring tomorrow.
 

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I can tell you that checking wiring other than obvious stuff, like is wire connected to sensor is really hard as wiring is protected in wrap. Sounds like a TCM issue, well documented on here and elsewhere.
 

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Ok, before I go changing the TCM out.... Should I take in to consideration that my transmission itself might just be done for? (crossing my fingers that it ain't!)
 

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There is no TCM in my Mazda 😱 just a PCM.. Luckily, I haven't gone out & bought a TCM just yet 😂 would I have to get the PCM programmed though if I bought a new 1? 'Cause I know that you don't have to do that with a TCM.
 

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I can tell you that checking wiring other than obvious stuff, like is wire connected to sensor is really hard as wiring is protected in wrap. Sounds like a TCM issue, well documented on here and elsewhere.
Checking for a wiring fault isn't that hard. You check resistance on each wire individually between the connector that plugs into the solenoid and the crisponing pin in the PCM or TCM harness connector. Then, check resistance between all the wires with the harnesses unplugged from the solenoid and PCM/TCM to make sure they aren't shorted together, and check for resistance between each individual wire between ground and power. It's also a good idea to check resistance across the two pins of the solenoid itself. Then, check resistance between the corresponding pins at the harness connector for the PCM or TCM with the solenoid plugged in, it should be similar to the reading you got at the solenoid itself. If it isn't but the wires individually test good without the solenoid plugged in then suspect the solenoid connector as being faulty.
 

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Shift solenoid "C" is the middle solenoid on the side with the 3 bigger solenoids. Is that the solenoid that you changed? What you should have done BEFORE buying a new solenoid, is to have swapped the "C" solenoid with either the "A" or "B" solenoid (A, B, & C solenoids are all the same part). Then you could see if the problem changed to another solenoid or stayed the same. If it stayed the same, then you would know that your original "C" solenoid is OK and no need to waste money on a new one.

There is no TCM on the 04 & 05 Mazda 3 (it was not added until 06), so any comments regarding a possibly faulty TCM is incorrect.

So, you are left with 3 possibilities:
  • The wiring from the transmission to the PCM.
  • The PCM.
  • The transmission.

And yes, it definitely COULD be a bad transmission. My 07 Mazda 3 had code P0757 (shift solenoid "B" stuck ON) and it was a bad transmission.

My troubleshooting process was as follows:
1) I had a spare known-good TCM, so I tried that. = No change.
2) Removed the transmission pan to change the fluid & filter and to swap the "B" solenoid with the "C" solenoid. While the transmission pan was removed, I also confirmed the TCM-to-Solenoid wiring was OK and also that the solenoid "clicked" with 12VDC applied. = No change.
3) Replaced the transmission with an "imported from Japan" used transmission with 50k max mileage. = All fixed!
 
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