08 mazda 5 P0758 shift solenoid B questions

I'm getting a 3 yr/36 warranty.

What is a WDS? Hopefully they will do that for me. What happens if it is not programmed to my 5?
 
Sorry, guess it was changed. VCM/IDS seems to be what Mazda uses now. It is basically the expensive hardware/software combination that must be used to program replacement vehicle modules, like your PCM. Sure it's a helpful tool for technicians, but the cost of equipment and software subscriptions are certainly passed on to consumers. Private shop on the corner will not be able to replace a PCM without investment and training.
 
Up to 07 the tcm was part of the pcm. Starting in 08 the tcm is a separate unit that bolts to the top of the trans under the battery box. The separate tcm doesn't require programming but is programmable for updates. A new tcm will come with the latest software at the time of production, but later versions may be available depending how long it sat on a shelf.
 
Got it back today. Now my wallet hurts. So far no issues.
Their recommendation is a fluid drain and new filter every 15k--not a flush. Those cause problems from what I've heard, so just drain and refill.
Hopefully my pain will help someone else avoid the same, or if nothing else get them back on the road sooner.
 
now my next adventure is getting the clutch replaced on my 95 B3000. At least that is a simple job with a much cheaper price. I just wish I could channel all this money into my project car instead. I'd have it back on the road in no time.
 
Up to 07 the tcm was part of the pcm. Starting in 08 the tcm is a separate unit that bolts to the top of the trans under the battery box. The separate tcm doesn't require programming but is programmable for updates. A new tcm will come with the latest software at the time of production, but later versions may be available depending how long it sat on a shelf.
Tell me more! Can you please cite a reference for this?
I am very curious if it would be worthwhile to pull the TCM from, say a '14, and stick it in my '08 to get the latest tranny logic? I am pretty confidant Mazda did not changed the transmission after '08, when they finally changed over to a 5sp auto. This would be a nice update if Mazda split the TCM and ECM from the PCM (but isn't this going backwards from the trend of integration/consolidation?).

EDIT: On 2nd though, the +'12 use the 2.5L engine so it is using a different power band. Perhaps '10 TCM is the better option, if it is a viable option at all.



Got it back today. Now my wallet hurts. So far no issues.
Their recommendation is a fluid drain and new filter every 15k--not a flush. Those cause problems from what I've heard, so just drain and refill.
Hopefully my pain will help someone else avoid the same, or if nothing else get them back on the road sooner.
Holy crap, really?? Drain and fill every 15K AND a new filter!?!? My question is, what type of driving conditions and what oil quality is this in consideration of? You can't blindly follow this without understanding how/why.

Not all oils are created equal and not all driving conditions are the same. Premium oils use a higher grade base stock and more/better additives for a better profile. I worked a short stint in materials management in a Parma company and I can tell you some raw chemicals/indigents are ridiculously expensive. General rule is that heat destroys oils. If you drive hard (high rpm) and in hot climate, it will break down the oil sooner and wear out the additives sooner. Auto trannys are programed to hunt for top gear for lower NVH and optimal MPG. This means it is shipping gears all the time (and why tiptronic/steptronic has it's place but most don't know why it's there or bother). City cars are harder (image all the stop and go gear changes) vs country cars which are pretty much crushing in top gear. Stock auto have a filter and cooler. The goal of the cooler is to keep the oil temp down so it doesn't get burnt (literally) and filter to keep it clean of containments (from wear and tear) so it can do its job. You can also add additional aux. filters and coolers if you feel you need more. Oil is oil and same thing applies to motor oil. Does it make sense to follow a set interval without knowing how/why ;)

Did they explain why a flush cause problems and are they referring to power flush (machine)? I have no experience with power flush but I would highly recommend flushing through the ATF return hose. It is more like a transfusion then a "flush". Equal parts in and out using the transmission pump so it is not unusual pressure that disturbs sediment that may have build up over time. There are also procedure to flush an engine but more don’t/wont’ care too.
 
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I'll try to find references later, but it would make more sense just to have a dealer check your tcm software for updates using their obd tool.

Edit: Adding references for validity. 08 Mazda 5 workshop manual:

2008 - Mazda5 - Transmission/Transaxle
TCM REMOVAL/INSTALLATION [FS5A-EL]
CAUTION:

Do not apply a shock to or touch the projection on the TCM, otherwise it may not operate normally.

1. Remove the battery cover. (See BATTERY REMOVAL/INSTALLATION [L3].)
2. Disconnect the negative battery cable.
3. Remove the battery duct. (See BATTERY REMOVAL/INSTALLATION [L3].)
4. Remove the battery, battery box and battery tray. (See BATTERY REMOVAL/INSTALLATION [L3].)
5. Remove in the order indicated in the table.
6. Install in the reverse order of removal.
xmWPo-8akuW9ymL_R7NhlHmRLsKQZkpvozVFkxpdYxI=s197-p-no


Modules that require programming (or configuration) will state so in the manual. Example:

2008 - Mazda5 - Engine
PCM REMOVAL/INSTALLATION [L3]
1. When replacing the PCM, perform the following:
PCM configuration (See PCM CONFIGURATION [L3].)

2. Remove the battery cover, battery duct, battery and battery tray with PCM. (See BATTERY REMOVAL/INSTALLATION [L3].)
3. Disconnect the PCM connector.
4. Remove the PCM from the battery tray.
 
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I'll try to find references later, but it would make more sense just to have a dealer check your tcm software for updates using their obd tool.
Agree but unless it is free, I don't like dealer service. Overprice and takes time/effort. My though was, I can prob pull the TCM from a you-pull-it (or ebay?) for cheap, for say Mazda3 since Mz5 do not exist. I'm in no hurray but a quick jim ellis check of Mz5 vs Mz3 will tell us if the TCM is interchangeable.

This is great to know that the TCM being separate starting '08.

Where'd you get the '08 service manual?
+2. Fellow '08 owners want to know :D
 
Agree but unless it is free, I don't like dealer service. Overprice and takes time/effort. My though was, I can prob pull the TCM from a you-pull-it (or ebay?) for cheap, for say Mazda3 since Mz5 do not exist. I'm in no hurray but a quick jim ellis check of Mz5 vs Mz3 will tell us if the TCM is interchangeable.

This is great to know that the TCM being separate starting '08.

+2. Fellow '08 owners want to know :D

I have a local source for the manual. PN# 9999-95-012B-08 if you want to try and track one down.

I know there is a healthy discontent with dealers but I still think that having the dealer search for updates is the only way to verify you have the correct software for your tcm. Even a junkyard/ebay unit will most likely not have the latest version and they don't really update them unless there is an issue to fix.
 
Good to know about the manual!


I'm not saying I plan to go out there and mess with the TCM, just good to know it is there. This is also a simple TCM upgrade for Maxima owners, which I did not do (had the tuxedo version).


Off topic - just noticed you, flcruising, and I are '08 Cooper Red owners (boom03). Best. Year. And. Color. Ever.? J/K :D
 
so far the rebuild is good....

Oh, by the way. I am wondering if there is any way to find my own posts easily, aside from subscribing to a thread. I did a 'find my posts' search and didn't see anything. I don't recall it in the forum rules either.
 
Off topic - just noticed you, flcruising, and I are '08 Cooper Red owners (boom03). Best. Year. And. Color. Ever.? J/K :D
Agreed!
so far the rebuild is good....

Oh, by the way. I am wondering if there is any way to find my own posts easily, aside from subscribing to a thread. I did a 'find my posts' search and didn't see anything. I don't recall it in the forum rules either.

Great to hear!

Yes, click your name on any post and there is the option to see all of your posts.
 
Thanks Aaron. I would have never guessed that. So many forums and so many methods.

Btw, still running good!
 
Hi all, this thread was quite useful because I just had this exact same problem.

I read this thread probably over a dozen times in the past few weeks trying to diagnose this with my mechanic.
It was unclear to me from this thread whether the TCM replacement or tranny rebuild actually fixed the OP's issue since he had both done at the same time....

The TCM replacement fixed my issue....

Here is a summary of my symptoms (this is in hindsight after working on this issue for weeks with my mechanic before taking it to mazda for tcm replacement):

2008 Mazda 5 with 135,000 km (I'm in canada).
Check engine light on, AT light comes on and whole car jerks as it shifts from 2nd to 1st when stopping for a stoplight.
Car jerks again as it shifts from 1st to 2nd.
Every stoplight same thing, whenever it shift from 2nd to 1st or 1st to 2nd same thing.
Now here is the kicker: If I pull over, turn off engine, pull out key, wait a minute, restart engine...AT light goes away and car drives perfectly normally.
for the rest of the day. Until the next morning when it happens again. Every morning. Same thing.
Sometime it would happen at night. Sometimes it happens from Park to reverse. But always every morning it would happen from 2nd to 1st coming to a stoplight.
It almost seems like a crappy computer needing rebooting every day to make it work temporarily...

Scanning the code with my scanner - it is the same code every time:
Code: p0758 Shift Selenoid B Electrical.
Pending code: p0758 Shift Selenoid B Electrical.

Took it to my trusted mechanic. A good guy.

He checked all the wires, seems fine.
Dropped the tranny pan, changed out a new Selenoid B ($210 for the part), changed the fluid using M-V (not mercon V), and changed the filter.
Unfortunately, this didn't do anything...the exact same problem came back the next day as usual.

The next option was to either replace the TCM and/or failing that replace the tranny.
My thinking was that it's unlikely to be the tranny since it shifts perfectly fine after a "reboot".
Mechanic found a used TCM but advised me that who knows what problems it has, and that only mazda could program it.
Best to go to mazda dealer to get a new one and have mazda program it and install it.


Dealer confirmed that TCM does indeed need programming.
They swapped new one in, now everything is fine after forking over $1500 ($1000 for the TCM + 2.5labour + taxes).

Just a comment here that it is really a crapshoot fixing this issue in hindsight.
It could have been the actual Selenoid B. It's what the code says. Duh.
It could have been the wiring.
Lastly it could be the TCM.
Might have been the tranny.

Basically trial and error and eliminate each variable and pay as you go :)

I don't know if bringing it to the dealer at the beginning would if they would have been able to determine that it was a bad TCM and not a bad Selenoid B. I doubt it and I would have likely payed dealer labour prices to muck around....

Again, crap shoot, and I'm out 2+ grand :)
At least it wasn't the tranny...

Hope this helps someone.
 
most of you guys have not idea what you are talking about or only know parts. no offense. I am a tech at a dealer. just to let the guy know with the issues the P0758 is an electrical issue. has nothing to do with mechanical in your trans. meaning the TCM was the issue to begin with. It did not need a rebuild. considering you didn't notice any problems until you got MIL on. also I just fixed this code on a 3 and would of being a loose pin at the trans plug close to the trans range switch up front where the linkage is. its the plug for the valve body. the plug is out side. and no you done flush or drain every every 15. if you flush with no additives every 30k you trans will work great. if you just drain and fill then do it every oil change. you should never buy different fluids for an auto. if you put the wrong fluid or a shelf fluid that claims it will work and you have problems down the road do you really think Valvoline or whatever will pay for that trans when the fluid eats seals and doesn't lube the clutches they way they need to be. ask a little more if you don't know. they are dealer techs on here. ask one next. ill at least get you in the right direction. I could of sent pics of the exact flow chart diag for that code. so you could see what we actually do at the dealer.
 
sorry for the lack of edit. so if can t understand my writing I will say slower. my computer does auto correct. except its actually wrong most of the time. well that and I was ranting. because I was mad. at people who think they know and really don't know things. hope my message helps you or someone else with same similar issue. on the FS5 trans 5 speed auto in 3 and 5. most of the solenoid codes the fix will be the TCM or loose pin at a connector to trans or broke wire. I will say I have yet to replace a solenoids of any kind on this trans for shifting concerns. I would not interchange unless you find one with same part number. I have tried this when see if this was the issue and it causes issues. They are differences in the TCM. software difference even tho same trans. These lines of code differences can damage things. If part numbers on side same you ll be fine. But if different I would not swap another one used one in.
 
sorry for the lack of edit. so if can t understand my writing I will say slower. my computer does auto correct. except its actually wrong most of the time. well that and I was ranting. because I was mad. at people who think they know and really don't know things. hope my message helps you or someone else with same similar issue. on the FS5 trans 5 speed auto in 3 and 5. most of the solenoid codes the fix will be the TCM or loose pin at a connector to trans or broke wire. I will say I have yet to replace a solenoids of any kind on this trans for shifting concerns. I would not interchange unless you find one with same part number. I have tried this when see if this was the issue and it causes issues. They are differences in the TCM. software difference even tho same trans. These lines of code differences can damage things. If part numbers on side same you ll be fine. But if different I would not swap another one used one in.
Hi autozam.

Glad to have your input. Would be great if you check in often. There are a lot of questions and not many answers, let alone your qualifications to answer questions correctly.

I have some questions I’m hoping you can clarify to better my understanding. Can you elaborate a bit on exactly "why" it dosn't work and “what” and “how” things are damaged if you plug in a TCM with a different part number (TCM from the same car as in same trans type, engine configuration, and ECU configuration – such as ’08-’10 (I am ASSuming ECU hasn’t changed) where the Mz5 uses the 5sp auto and same 2.3 I4)? I’ve always been under the impression that TCM updates are somewhat proprietary and not publicly released (unless leaked then it would be all over news). My ASSumption is due to liability reasons. Not that I have any issue with my TCM but what kind of problem would I get if I plug a ’10 TCM into my ’08 (same 5sp, 2.3 I4)?


I understand the TCM is microprocessor running firmware with transmission control/shift logic – now with smart learning capabilities. This is connected and closely in sync with the ECU (decoupled starting ’08). What is the root of the problem with an ’08 ECU not being compatible with the newer ’10 TCM firmware? Do they perform some sort of validation/version checking with each other? If so and one invalidates the other, wouldn’t you get an engine and/or transmission light warning not to proceed? In this case, would it be possible to flash the TCM to be compatible to the ECU or vice versa? OR is that problem more with ‘learned’ shift adapt that resides in now separate TCM and ECU that are out of sync? The intelligent modern car has learn capable everything (being dramatic). Would it remedy the problem with a reset of both? OR is the problem with non-backwards compatibility of the TCM not being able to recognize the older ECU? If it is backward compatibility issues then this means both the ECU and TCM need to be upgraded at the same time be it physical replacement or flash/software update, is that correct? This would also mean an ’10 car with the newer TCM would also have a newer ECU flash. Or are there additional undocumented changes/updates (components that did not physically exist before) in the transmission within those minor years that bind specific firmware versions (I don’t see this being likely between minor revisions from ’08-’10 as it would be another major cost/overhaul for a small shop like Mazda). Mazda did a major upgrade during the mid-cycle refresh where the ’06-’07 was a 4sp auto (apparently the TCM and ECU were integrated) and the ’08-’10 are 5sp auto (TCM and ECU were decoupled).

I’m sure there’s much more to this than my simple understanding. I deal with system integrations and would like to know the root of the problem for my understanding on how they work –and not work. Any input would be great.



For clarification, it seems within the last few years that TCMs and ECUs are becoming smarter and smarter, which is why I was surprise loosenut identified they were decoupled starting ’08 while mfgs focus more on consolidation/integration. In the Nissan/Infiniti world, last I know in the mid 2000s, which is a long time ago, a TCM upgrade IS physically swapping in a new unit – the TCM unit/box has new hardware and firmware. The systems are likely a lot less integrated than today’s cars.


http://certified-transmission.blogspot.com/2012/06/written-by-jim-stokes-warranty.html
http://certified-transmission.blogspot.com/2012/08/top-10-install-problems-part-2.html
 
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most of you guys have not idea what you are talking about or only know parts. no offense. I am a tech at a dealer. just to let the guy know with the issues the P0758 is an electrical issue. has nothing to do with mechanical in your trans. meaning the TCM was the issue to begin with. It did not need a rebuild. considering you didn't notice any problems until you got MIL on. also I just fixed this code on a 3 and would of being a loose pin at the trans plug close to the trans range switch up front where the linkage is. its the plug for the valve body. the plug is out side. and no you done flush or drain every every 15. if you flush with no additives every 30k you trans will work great. if you just drain and fill then do it every oil change. you should never buy different fluids for an auto. if you put the wrong fluid or a shelf fluid that claims it will work and you have problems down the road do you really think Valvoline or whatever will pay for that trans when the fluid eats seals and doesn't lube the clutches they way they need to be. ask a little more if you don't know. they are dealer techs on here. ask one next. ill at least get you in the right direction. I could of sent pics of the exact flow chart diag for that code. so you could see what we actually do at the dealer.

I guess you should have read my post in this thread from last year explaining how this problem is electrical, not mechanical.
I was too late, but at least I wasn't insulting.
 
Hi All,

I'm having the same issues, CEL and AT, stuck in 3rd, hard shifts, every morning, but sometimes working fine by the afternoon. Unfortunately, I know NOTHING about cars, I only understood about 10% of this thread and I am terrified of this issue. I'm a young, broke girl who paid way too much for her '08 Mazda 3 with 100k miles. I've already put a new alternator into her this year, which wasn't my idea of 'cheap' and now the thought of a new transmission is keeping me up at night. I have NO IDEA what to do and I was hoping you guys might be able to offer some advice. Where do I even start? Go to the dealership as they might be able to know what is wrong right off the bat as mentioned above, and potentially save myself several attempts? Or go to a local shop and tell them to...? I honestly can't decipher what the issue here is, some people are saying electrical and others replace the solenoid... where do I start? Any help is so so much appreciated, I feel way in over my head!

Thank you so much.
 
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