08 mazda 5 P0758 shift solenoid B questions

B

byakk0

Member
:
Mazda 5 Touring
Hey all. Hope someone can help me here.
08 Mazda5, 110k, automatic. I got it at 97k, previous (1 owner) had all dealer service intervals done. Not positive on how often tranny fluid was changed, but it looks brownish.

Anyway, when the CEL and the AT light pop on, it shifts hard, esp in reverse. Clear the codes it shifts normal until the light comes on, which is quick. I haven't driven it very far since the lights have come on, hopefully a tranny fluid change will do the trick. Codes read P0758 code-shift solenoid B

Anyway, the biggest question I have right now, calling around for parts, none of the main FLAPS (NAPA, O'Reily, ect) even show the parts.
The local Mazda dealership showed 7 different shift solenoids, at varying <$100 prices, and wasn't sure which solenoid was 'B'.
I had it to the Aamco, and they think it may be just the shift solenoid sensor, but just speaking to the dealer the guy wasn't sure what sensor that would be.

Does anyone have any diagrams showing which solenoid would be regulated by shift sensor B, and where that sensor would even be?

Also, how can I tell exactly which transmission I have?

Thanks!
Hazen
 
Also, just found out it uses MV type fluid, not regular ATF. Unfortunately its only available at the dealer for $10 ea. Can you uses other types or is it not a good idea?
 
mobil 1 atf will work... and i highly recommend it as it is a full synthetic. I used it in my old mazda 3 and had over 100k with no issues in the trans. I made the mistake of going cheap on my ATF this recent flush (about a year and a half ago) and used Castrol, i will be switching it out in the next few weeks because i have been having hard shifts and all that fun stuff.
 
byakk0 said:
Also, just found out it uses MV type fluid, not regular ATF. Unfortunately its only available at the dealer for $10 ea. Can you uses other types or is it not a good idea?
Click to expand...

Mazda 5 auto transmissions appear to require frequent ATF changes - lots of discussion here http://www.mazdas247.com/forum/showthread.php?123824925-ATF-Recommendations-What-fluid-cooler-filter-Share-your-experience-on-the-Mz5!&highlight=

Many ATFs don't quote compatibility with Mazda M-V. I'm using Castrol Import Multi-Vehicle ATF with ~30k miles 3x change interval (1 time drain & change @20, 25, 30k miles). It's cheap insurance to change it often. No problems so far - after having transmission replaced by Mazda @20k miles, I'm ~90k miles now.
 
kw_da said:
Mazda 5 auto transmissions appear to require frequent ATF changes - lots of discussion here http://www.mazdas247.com/forum/showthread.php?123824925-ATF-Recommendations-What-fluid-cooler-filter-Share-your-experience-on-the-Mz5!&highlight=

Many ATFs don't quote compatibility with Mazda M-V. I'm using Castrol Import Multi-Vehicle ATF with ~30k miles 3x change interval (1 time drain & change @20, 25, 30k miles). It's cheap insurance to change it often. No problems so far - after having transmission replaced by Mazda @20k miles, I'm ~90k miles now.
Click to expand...

Thanks.

NAPA just informed me Valvoline MV will work too. I got some diagrams (will post later) of the solenoids, and which are which.

So you're saying you change it every 5000 miles?
 
byakk0 said:
Thanks.

So you're saying you change it every 5000 miles?
Click to expand...
I change the ATF every 30k miles. It takes 3 drain & refills to completely change most of the ATF, I just do it with the oil change (every 5k), 3 times right before the 30k interval.

In that thread I linked earlier, there is a list of compatible ATF fluids. Mobil 1 ATF used to say they were compatible, but for some reason removed it from their list - probably just didn't bother to get it recertified.
 
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oh, ok. Hopefully things are still ok with it. The fluid looked like motor oil it was so dark, and the magnet in the bottom of the pan looked like a flower. No idea when it was last changed. The filter had FoMoCo stamped on it, so either the PO used the dealer regularly, or its never been done in 110k. Yikes. (flame2)
 
According to the transmission supply place I got the parts from, the two smaller solenoids should give a resistance reading of about 4.5 ohms and the three larger ones should be in the range of 20-30 ohms.
I got 25 on E, 32 on D for the two small ones, 30 on the pressure control solenoid, A, and on the shift solenoids A, 10 ohms; B, 9 ohms; and C, 7 ohms.
These all are fairly consistent with each other, so I am hoping that I don't have any issues. I am going to try just changing the fluid and filter for now and see what happens.





 
unfortunately I bought the filter that has the shorter pickup tube, so I may have to wait until Monday to finish the job once I swap the wrong for the right one. No local auto parts places have the correct one.
 
Just wanted follow up and post my results. (I hate reading help/how-to threads that leave you hanging!)

Got the correct filter instaleld today, put it all back together and filled it with new fluid. I didn't change any of the solenoids.
Drove it to O-Reily's to clear the codes and it has worked like charm ever since.

Just wanted to say thanks, and document my solution here. Hopefully someone else will benefit by it.
 
Ack. It didn't work. This attempt only lasted one day, so I swapped out solenoid B and gave it a new round of fluid. The new fluid I drained out didn't even have 10 miles on it, but it came out nearly as dark as the stuff before. I didn't flush the whole system, so it was mixed with old fluid that was still in the torque converter.

But, even changing Solenoid B didn't do anything. I changed it out yesterday and I didn't get 5 miles before the AT and ENG lights kicked back on.
I'm wondering if a tranny fluid change (again) would help.
Otherwise, I am at a loss here. Any ideas?
 
After changing Solenoid B did you get continuing bad behaviour from the tranny or just the codes came back?
 
To be honest I haven't had the time to read the codes yet. I plan to do that today, but I suspect it will be the same code, P0758.
But, yes, the bad behavior returned. It worked correctly for maybe 5 miles before the CEL and AT lights came back on, just like previously, and it started shifting hard once more.
I'm at a loss at this point, and I don't want to go pay high $$$ to the dealer, but I will do what is necessary in the end. I can do most repairs myself (Who the heck invented that stupid 'stretch to fit AC belt anyway!) but dropping the tranny and repairing it is beyond my home shop capabilities. Guess I could do it, but the headaches involved...
Anyway, I stopped a local tranny shop, a one man crew sort of shop and had a chit chat with him about it. He admitted to not being familiar with Mazda transmissions, but from what I was able to tell him he surmised that even though the fluid did not smell burnt, because it was full of grit (the magnet in the pan looked like a flower) and it was black, that the clutches were probably burnt, or maybe the torque converter was bad-or both.
I may be looking at a rebuilt, used, or new.
I was not very impressed Aamco.

My wife was researching it a little today and discovered that the 08 M5 tranny has been known to have issues.

Katner, I see you have an 08. Hopefully yours won't have the same issues as mine. How many miles is on it, and have you kept the tranny fluid changed every 30k or so? The previous/original owner of mine had it serviced at recommended intervals, but judging from the color of the fluid, it looks like the transmission was neglected.
 
Well, good news, sorta. Taking the 5 in today for a tranny rebuild. It's a different shop than the one I previously mentioned, but has come by way of many good recommendations from various people. When I spoke to them last week he was very knowledgeable, especially with the 5. New exactly what I was talking about. Said he had one in recently, had a Ford Focus that day, and that his daughter has a 5. He'll do a diagnosis beforehand, but I'll be surprised if it is anything short of a rebuild. And apparently, it is necessary to use the Mazda MV transmission fluid and not just some generic Mercon V. $9 a pop, seems a bit expensive, but I guess better to do it right.

And, completely unrelated, I was happy to discover the 5 has a timing chain instead of a belt. I was never able to get out of the dealer when the PO had last done the timing belt. But if it is a chain, it should last a long time and I am not as concerned.
 
I think it's important to note that Mazda specifies MV as in "multi vehicle" transmission fluid. This is not the same as "Mercon V". Most fluid manufacturers list the makes and models their products are compatible with right on the bottle and certainly on their website. I imagine there could be serious damage resulting from not knowing that "MV" and "Mercon V" are different.
 
byakk0 said:
Well, good news, sorta. Taking the 5 in today for a tranny rebuild. It's a different shop than the one I previously mentioned, but has come by way of many good recommendations from various people. When I spoke to them last week he was very knowledgeable, especially with the 5. New exactly what I was talking about. Said he had one in recently, had a Ford Focus that day, and that his daughter has a 5. He'll do a diagnosis beforehand, but I'll be surprised if it is anything short of a rebuild. And apparently, it is necessary to use the Mazda MV transmission fluid and not just some generic Mercon V. $9 a pop, seems a bit expensive, but I guess better to do it right.
Click to expand...

Personally, I'd use a good aftermarket ATF instead of Mazda's MV, for the same or less price, I think a name brand aftermarket would perform better. After all, the problem probably occurred with the MV. Just curious about pricing, what is your estimate for the tranny rebuild & for comparison, approximately where in the US is the repair shop. Thanks.
 
P0758 is strictly electrical related. Rebuilding the transmission is a waste of $$. Here is the workshop manual for the transmission, page 54 has the code and diagnostic/repair procedure. Problem is that this manual is for the FN4A, whereas '08+ is FN5A so the ATX-PCM wire harness is likely different. You should be able to trace the wiring and still follow the diagnostic though.

https://onedrive.live.com/redir?resid=FB70D2F1B0FCDE6C!6751&authkey=!AAJ6JP6r3QAHKnU&ithint=file,pdf

Also, if you are so inclined, you can perform a flush yourself with a couple gallons of inexpensive Mercon V, before doing the final exchange with factory MV or another approved fluid (I run Valvoline Maxlife Dex/Merc, but is has been discontinued in my area). What you do is remove the return line from the ATF cooler and extend it to a large catch container or oil drain pan. Have an assistant start the vehicle and prepare to fill a couple quarts at a time while it is being pumped out by the transmission. Don't let it get too far ahead of you, so you will likely start/stop the engine multiple times while you perform this procedure.

http://repairpal.com/OBD-II-Code-P0758
 
Awesome info Aaron...a little late though, unfortunately...Read on.

I'm in Boise. The rough estimate, with labor, is around $2800....but....
The heavy particulates found in my fluid was as concerning to the transmission shop as well as myself. As I mentioned before, the magnet in the tranny pan had so much on it it looked like a flower. I replaced shift solenoid B as the error indicates and still the problem persisted.

They pulled the tranny and tore it apart today, and they were fully expecting burned/broken parts. I bet you (Aaron) are going to think, 'well duh' on this one ;) , but given my symptoms and description they found nothing wrong visibly. Well, I'm hoping it wan't a waste of time or money at this point, but he proceeds to inform me that with that amount of particulates it is more than likely the torque converter. It's all apart anyway, so I'm having them rebuild it instead of dump the old parts back in. At this point, I may as well.

Continuing on, further research by them indicates that either there is a short to the TCM or the TCM itself is bad. (transmission control module). I'll have them replace that while they are at it.

Hopefully the problem will be repaired through all of this, otherwise, as Dave Ramsey likes to say, it will have to go down in the books as 'Stupid Tax'

Here it is all torn apart, if you are interested.
20141016_162957.jpg
 
Sorry I didn't get that to you sooner.

FYI - the PCM (next to the battery) is the ECM/TCM. It will require programming to work with your vehicle and instrument gauges. A WDS is required.

Metal particles from a torque converter? I guess it's possible. Though you will have new internals, electrical testing is likely still in order. Hope they give you a good warranty.
 
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