P0753 & AT Light - 2007 Mazda 2.3L - Transmission Fluid Change & Troubleshooting

P0753 & AT Light - 2007 Mazda 2.3L - Transmission Fluid Change & Troubleshooting

Hi everyone,

Hoping I could get some help on this issue. Bought a 2007 Mazda 3s 2.3 with 5 speed automatic with 96k on it. I know the owner she has taken very good car of the car oil changes, brakes etc. Only thing she never changed was the transmission fluid. When I purchased the car I started full tune up. New plugs, synthetic oil, filters. She never change the transmission fluid on the car, she even called Mazda and they told her that the car doesn't have a service interval for the transmission. I was there when she called. I thought that odd.

Anyways I decided to change the fluid, it was brownish. Didn't smell burnt and there were no shifting issues. I did a partial change. Dropped the pan, changed the filter. Cleaned the magnet which has slushy oil and metal on it as expected. Took about 3.5 qts of fluid.

After the change car ran as normal for a few weeks. In total it was 1,025k miles later that I got an issue. The weather just started getting colder here in NJ. Started the car in the morning and let it warm up for 10 minutes which is my norm. Put the car in reverse, car jerked jolted and the check engine and AT popped up. Shifted to drive and the same thing. So stopped the car and connected my ODB and TunerPro gave me a P0753 error "Shift solenoid A electrical malfunction". I then shut the car off and pulled the battery to see if it was just a fluke error code. Gave the car about 10 minutes and reconnected. Started car no check engine, shifting was normal. Went to work, worked, came home no issues.

Next morning back to the same issue. P0753 hard shift. So at that point I figured might as well do the full transmission flush. Using royal purple did it. Once the color was red coming out of the cooler hose shut the car off and pulled the battery. Then reconnected battery warmed up the car and test drove about 10 miles. Everything was smooth, shifting no issues.

Next morning back to P0753. So I then started the tech tree procedure located here:
https://euroesi.mazda.co.jp/esicont/eu_eng/mazda3/20110724140058/html/id050221818800.html

I did almost all of these but couldn't figure out how to do 4 & 5. How do you test the same wire for power and ground? Little above my knowledge. Did the resistance testing on all solenoids and results came back in spec.

Had a guy on the boards who is a mechanic tell me to check the pins on the TCM plug (the female side) and the Transaxle connector (Primary) for widening. This weekend I took the TCM plug and tightened them from the front after taking off the white protector cover off. The transaxle I couldn't figure out how to take the white protector plastic cover off so carefully stuck a screw driver in the back top of square pins and pushed them down. Well after that reconnected the battery, warmed car up, took a drive and perfect.

This morning (its about 50 degrees here in NJ today) back to the same problem. This time I connected my ODB adapter and Torque while car was running and cleared the code. After clearing the code car shifts fine.

I am thinking about dropping the pan and swapping Solenoid A with B or C since they appear to be the same. Someone on youtube is saying that mazda has the solenoids labeled incorrectly. That the 2 smaller one on the passenger side are actually A & B as per Ford documentation. The 3 on the drivers side (which are bigger) are what Mazda has labeled as A B C.



http://s19.postimg.org/qd0be084j/Capture_Solenoids_Mazda.jpg

https://euroesi.mazda.co.jp/esicont/eu_eng/mazda3/20110724140058/html/id051721293200.html

Thread has been updated, see my last post.
 
Last edited:
V
2014 Mazda3 S GT auto, 2008 MX5 6-speed
I would believe Ford made a mistake before I believe Mazda did. Did you check to see whether the solenoids are available and how much they cost?
If you're going to go through pulling the pan again, it'd be nice to have new parts handy.
 
I think they are about $100 bucks or so. But I would like to narrow it down to a solenoid or TCM before I drop more money.
 
V
2014 Mazda3 S GT auto, 2008 MX5 6-speed
A bad ground could rear its ugly head when temps drop. Have you checked/cleaned any relevant ground connections? My 89 MX6 GT's auto transmission was shifting fine when I sold the car with 160,000 miles on it. At one point I thought one of the solenoids had failed but the only issue was slightly low-level trans fluid.
In your case, it'd be good to have an idea as to how often those solenoids fail.
 

1st Gen

Hmmm
Contributor
V
1991 Protege LX
I'm having the same code so went right to the solenoids. Bought them from Napa for $36 each. Didn't fix the problem. Am leaning towards the TCM.
Updates are appreciated.
 
I thought i updated this thread. Anyways, I ended up swapping the solenoids that are in the transmission very simple to do and still had the problem between 3rd and 4th which obviously means the solenoids were okay. I ended up swapping the TCM and that solve the problem. The TCM is right above the transmission and I guess the crappy soldering that you're doing nowadays along with all that he caused the issue. Car was fixed after the TCM and the battery pulling to reset the computer.

PS I got a brand new TCM online do your homework and I would personally not buy a refurbished one since these things are sealed pretty watertight from the factory. And every condition one is going to be done by somebody by hand.

By the way the YouTube clip where the guy mentions the solenoids were incorrect label is absolutely wrong. When you're under the transmission the two solenoids are identical in size and function. This is the easiest bet to swap the solenoids and according to a mazda mechanic those solenoids rarely ever go bad so suspect of TCM right away.

Sent from my HTC One M9 using Tapatalk
 
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I'm having the same code so went right to the solenoids. Bought them from Napa for $36 each. Didn't fix the problem. Am leaning towards the TCM.
Updates are appreciated.
Did you change your transmission fluid recently? Just trying to see if there is a correlation or it's just that my TCM happen to go bad after the fluid change.

Sent from my HTC One M9 using Tapatalk
 

1st Gen

Hmmm
Contributor
V
1991 Protege LX
My wife and I bought this car Labor Day, 2009. The car shifted a little weird so we complained. They flushed the tranny oil and replaced it. I haven't done anything to it since then.
Edit- The TCM I found online is $700~ I don't want rebuilt but I'm sure there are cheaper alternatives.
Thanks for getting back to this so fast. It helped.
 
Last edited:

Rivman

f.o.r.g.
V
'08 Mazda Sport GT / '93 Mazda 323 / '68 Buick Riviera GS
2008 Mazda 3 GT Hatch 2.3L with Auto Trans - got the 'dreaded' yellow AT light and CEL at about 200K kms. CEL was a PO758 - and the problem was intermittent, clearing the code didn't help and the transmission fluid level check was OK. Yellow Light, harsh shift, 3rd gear 'safe' mode only, turn key off- restart - all OK, till next occurrence, repeat procedure, all OK till next time, and so on. Check connectors and grounds. The transmission when working, was working fine, but the vehicle was unreliable because of the CEL, and the AT light which might decide to appear at anytime, or go away for a week or two, or not - talk about electrical gremlins !
After extensive research on the internet, and checking at various Mazda Forums, it turns out that TCM failure is often the culprit, and is a very common failure. A TCM failure will cause a CEL light and the AT light. The unit mounts to the top of the transmission and absorbs a lot of engine and transmission heat, which may contribute to the failure of the Transmission Control Module. New TCMs are quite expensive and make sure you have the latest version of the part, L34T-18-9E1E. The new part is VIN compatible so have it available. The last letter E is the latest version of the TCM, and it is a 'plug 'n play' part - no programming needed.
If you are a gambler, you can get your old TCM rebuilt or replaced for around $300 US + a $150US core charge. The core charge is refundable if your old TCM is repairable, which most of them are. You can also try to get a used TCM, again if you are a gambler, and you can find one, but the revision number must, or should be VIN compatible.
New units will carry a 1 year Mazda warranty, and are non-returnable as they are an electrical part - once installed, you own it !
So there you have it - Mazda obviously has a long term reliability problem with this particular part, and to date, has NOT issued any TSBs to cover the many failures over different years and models of Mazda. So dealers, and service techs will continue to misdiagnose your problem, and charge you for parts and services that were not needed, or did not eliminate the problem - some may even sum up the situation by stating you need a new, or rebuilt transmission, which is and may be a very expensive fix that can cost more than the actual value of the vehicle needing the repair !

No wonder they earn the title - 'stealerships' !!

Because of this 'long term reliability' problem, which Mazda chooses to continue to ignore.
Even though I did manage to cure the problem DIY, with a $650 Mazda part, I will never own another Mazda product.
I do hope this lengthy post may help others who nave an unexpected CEL, and that dreaded yellow AT light !
 
Last edited:
V
2014 Mazda3 S GT auto, 2008 MX5 6-speed
A neighbor has a Mini Clubman with 39,000 miles on it. Last February, two coils failed and wiped out their sparkplugs. Because of the misfiring, the catalytic converter is probably life-shortened. This is not uncommon for BMWs in general. If her car hadn't been under warranty, the bill would've been very heavy.

Your $650 TCM failed at 124,000 miles and for that you will never buy another Mazda? My wife's Honda Accord transmission failed at 60,000 miles. I guess no one should buy Hondas, either. Seriously, if the TCM failure was your biggest issue, consider yourself luckier than 99% of vehicle owners in the world.
 
V
Mazda 5
HELP! Same problem. TCM?? P0753 but already replaced the solenoids.

Hello-

I am experiencing the same issue with my wife's 2008 Mazda 5 as of a week ago from the time of this post. Otherwise this has been a very reliable vehicle and never had any problems. Just routine maintenance like brake pads, oil changes etc, most of which I've been able to comfortably handle myself from our garage. Recently she got the dreaded CEL & AT light along with the vehicle unable to shift into the higher gears. I could tell immediately when she called me that the car was not shifting, in her case into gears 4 or 5. So of course the following day I had the check engine light pulled at my local friendly Autozone. Turned out to be the P0753 code. Considering this car has been cared for and didn't appear to have any suspect wiring harnesses, damaged or exposed wires upon visual inspection and the transmission has always been smooth as glass shifting and other than carting around 3 small kids has not had any undo stress added to it like hauling or unruly driving I felt pretty confident that the solenoid A was in fact the culprit. So I purchased a full kit with reputable seller product quality. So I went ahead and successfully dropped the old transmission oil and filter, replaced both Solenoid A & B while in there (figured might as well and would offer some added piece of mind). The old fluid was in decent shape considering the car has 140k miles on it now. Cleaned everything up real meticulously, got the gasket in place, sealed and tightened and filled back up what was dropped with the pan (approx 3.5 quarts) annnnnnnd

STILL THE SAME PROBLEM. So I went and pulled the codes again to rule out any changes and yep, still the same P0753.

So I wanted to check in with everyone since there doesn't seem to be an abundance of info on this floating around the internet...has anyone else had success in changing out there old TCM? Is it fair to say that a faulty TCM could in fact be the culprit here and cause the P0753 code??!

I appreciate all help and feedback as I intend to post my results to help with any others out there suffering from this issue as well. I'm leaning towards replacing the TCM since it is not a difficult part to replace albeit it is an expensive assumption to make. Not sure what the diagnostics are in diagnosing a bad one with an Olmmeter.

All feedback much appreciated!!
 
Hello-

I am experiencing the same issue with my wife's 2008 Mazda 5 as of a week ago from the time of this post. Otherwise this has been a very reliable vehicle and never had any problems. Just routine maintenance like brake pads, oil changes etc, most of which I've been able to comfortably handle myself from our garage. Recently she got the dreaded CEL & AT light along with the vehicle unable to shift into the higher gears. I could tell immediately when she called me that the car was not shifting, in her case into gears 4 or 5. So of course the following day I had the check engine light pulled at my local friendly Autozone. Turned out to be the P0753 code. Considering this car has been cared for and didn't appear to have any suspect wiring harnesses, damaged or exposed wires upon visual inspection and the transmission has always been smooth as glass shifting and other than carting around 3 small kids has not had any undo stress added to it like hauling or unruly driving I felt pretty confident that the solenoid A was in fact the culprit. So I purchased a full kit with reputable seller product quality. So I went ahead and successfully dropped the old transmission oil and filter, replaced both Solenoid A & B while in there (figured might as well and would offer some added piece of mind). The old fluid was in decent shape considering the car has 140k miles on it now. Cleaned everything up real meticulously, got the gasket in place, sealed and tightened and filled back up what was dropped with the pan (approx 3.5 quarts) annnnnnnd

STILL THE SAME PROBLEM. So I went and pulled the codes again to rule out any changes and yep, still the same P0753.

So I wanted to check in with everyone since there doesn't seem to be an abundance of info on this floating around the internet...has anyone else had success in changing out there old TCM? Is it fair to say that a faulty TCM could in fact be the culprit here and cause the P0753 code??!

I appreciate all help and feedback as I intend to post my results to help with any others out there suffering from this issue as well. I'm leaning towards replacing the TCM since it is not a difficult part to replace albeit it is an expensive assumption to make. Not sure what the diagnostics are in diagnosing a bad one with an Olmmeter.

All feedback much appreciated!!
The TCM is probably toast if its the exact same situation as mine. Its right over the transmission and was pretty expensive when I changed it. I think I paid like 400 or something online and its OEM. Car has been fine since then. When the car shifts from 3 to 4 after an aggressive acceleration, we feel shift shock which apparently is another problem inside the tranny. Something with the valves or what not. It could also be related to the front passenger mount again the shift shock issue.

The P0753 chances are its your TCM. Not that hard of a job to do I also put a metal square under it to prevent or block some of the heat radiating up from the tranny.

BTW have you been servicing your transmission fluid on time? Previous owner never changed the fluid till I got a hold of it and I changed it at 100k if memory serves me right. Shortly after that the TCM went, could be related could not. The shift shock could also be related to the fluid not being changed till late.

Also make sure you check your fluid after the car has warmed up to operating temperature then drive it and then check it again. Checking transmission fluid level is very important and varies from vehicle to vehicle.
 
Last edited:
V
Mazda 5
This is great feedback. Thank you guys. So, currently have successfully removed the TCM (Transmission Control Module). I've found that the companies offering to rebuild these modules offer much better warranties for approx $200-300 where you simply ship them the defective module you removed from these year model Mazda 5's. The dealership on the other hand sells this part brand new OEM for double this amount....I even saw one for $700 online....with ONLY a 1-year warranty. Um nah I think gonna take my chances with the rebuild and have a better guarantee. I'll keep everyone posted once I get it back and installed. I feel confident I've pin pointed the problem bc everything else checks out no problems.
 
I also had a P0753 and AT Light pop up couple weeks ago. Drove it 60 miles home in limp mode :/ and it sat there till I fixed it.

Read this thread and other forums. I ran the tests listed by OP and was gettin strange results while the suspected TCM was plugged in. Based on that I determined the TCm went bad.

I decided to risk using the company that sold rebuilt TCM's. Had a choice of sending my TCM to be repaired and sent back ($200), but to save time I spent $300 for a used TCM and $150 for a core charge for my old TCM. I installed it in the suggested relocation spot (zip tied to brake lines, I protected the brake lines with a rubber mat to prevent metal rubbing and making a hole in the future).

It works perfect so far and I got a 1 year warranty on the refurbished TCM.

I've shipped the core TCM back and I'm waiting for the refund. Not sure if I can say the company name due to forum rules, but I saw them recommended in "a" forum (don't remember) and I recommend them as well.

All thanks to the internet and this forum for a somewhat speedy recovery for my mazda 3.
 

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