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Discussion Starter #1
Symptoms:

Car runs and shifts OK. AT light and Check Engine light are on. When I shut the car off, the AT light goes away upon restarting, but Check Engine stays on. Drive down the road until 5th gear, all is well. When it goes to downshift, there is a small jerk, and AT light comes back. Car still operates in all five gears. If I erase the code it comes back with P0778 Pressure Control Solenoid B Electrical. This looks like a very labor intensive project.

This is a 2008 Mazda 3 2.3 Liter with almost 190K miles on it. TCM and a couple things replaced in there a year ago. I am just wondering if I should spend 600 bucks in a car that I have already spent too much on. I am retired and on a fixed income.

So the main question comes down to: Is it safe to drive the car like this?
 

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... So the main question comes down to: Is it safe to drive the car like this?
My main question would be the maintenance history of the A/T fluid and current level and quality of the fluid. Yes, this is an electrical code, however a fluid issue can cause all kinds of different issues. So let's get that one answered, before talking about hanging on any parts.
 

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My main question would be the maintenance history of the A/T fluid and current level and quality of the fluid. Yes, this is an electrical code, however a fluid issue can cause all kinds of different issues. So let's get that one answered, before talking about hanging on any parts.
Thanks for your response. Fluid level is good, and the fluid was changed along with a output speed sensor and pan replacement in February. Car is not "limping", though I certainly chose to drive it home less aggressively than usual. :)
 

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Ok, then with the fluid being good it's time to move on to the code. You mentioned a $600 cost for repair - is that an actual estimate from a shop, or just someone's ballpark guess? In any case, I'd want to at least know that a resistance test has been done on the solenoids, prior to getting into any actual repair. If that test has not been done yet, it's not a very difficult thing to DIY, if you're into that. If not, it shouldn't cost over $50 or so for a shop to do that one.
 

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What most service shop rates are and charges for services is always inaccurately posted. Most shop have an hourly rate and the US nation wide average is 95 per hour. For a service procedure most will use a labor guide but still have a one hour minimum.
Many service shops may give a prorate or adjustment from that first hour or diagnostic work if you continue to have the actual service and repair done.
If anyone goes to a service shop you need to read clearly what you will be getting and if you are not sure ASK the service writer.
The fluid change as described may have only been a pan and filter only and not a complete flush. There is NO WAY to determine the true state of transmission fluid or for that matter any fluid without a sample analysis.
For any transmission service issue that inexperienced individuals are getting regarding and especially with a computer control automatic transmission should be taken to a shop that primarily specializes in transmission or to the Dealer.


Here is at least one member besides myself that believes in having the*oil or fluids(*motor oil) checked out by way of analysis.

*
https://www.mazda3forums.com/667-powertrain-2010-2013/754290-used-oil-analysis-11k-oci.html
 

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Discussion Starter #6
The work on the transmission in February was done by someone who ONLY does automatic transmissions. When I looked it up on the net to get an idea what all was involved in a diagnosis, it required a great deal (with my limited skill set) of disassembly just to get to the point where you are able to get readings. My question remains: Is it safe to drive the car?
 

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The work on the transmission in February was done by someone who ONLY does automatic transmissions. When I looked it up on the net to get an idea what all was involved in a diagnosis, it required a great deal (with my limited skill set) of disassembly just to get to the point where you are able to get readings. My question remains: Is it safe to drive the car?
I am very glad that you spent the time to learn a little off the forum with your problem. :grin2:

As for the question about "safe" to drive.... I often get asked this from customers that call and I will tell you the same thing. There is a problem that needs to be resolved before the the warning letting you know something is wrong turns to calling AAA to get towed to a shop! :wink2:

I am wondering why to do not contact the transmission shop you have already done business with?
 

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Deep runs the sarcasm in this one. <Best Yoda impression> :wink2:
This was NOT meant to be sarcastic. The thing is many join forums thinking that there is an answer and that all knowing members (sarcastic) will have the answers. But the reality is it becomes a guessing game that many members compete to guess the solution and become the FORUM GURU for all! In the real world which some of us actually do Diagnostic and Auto Technical servicing it is much different. So when I saw you found some "GOOD" information off the forum I paid you a compliment! Sir! :wink2:

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"nothing to be learned here....move along!"

:laugh:
 

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The work on the transmission in February was done by someone who ONLY does automatic transmissions. When I looked it up on the net to get an idea what all was involved in a diagnosis, it required a great deal (with my limited skill set) of disassembly just to get to the point where you are able to get readings. My question remains: Is it safe to drive the car?
I tired to upload the pages from the service manual for a 2007 Mazda 3, but apparently my limit is 20KB - WTF?. I'm pretty sure you have this same transmission. PM me and I'll email it to you. The code is for a part that is in the secondary valve body. That is not accessed by the transmission oil pan under the car. There is a second cover on the transmission that is accessed from under the battery box and it is near the firewall. The procedure has some debugging steps you can do with just an ohm meter. If you are real lucky, it may just be a connector that isn't fully seated. It could be a damaged pin inside the connector on the connector side or the transmission side. It could be a bad solenoid. I haven't been in the secondary valve body myself, but I've done a repair in the main valve body. I don't think it is that big of a deal to take off the cover and change a solenoid.
 

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Thanks for your response. Fluid level is good, and the fluid was changed along with a output speed sensor and pan replacement in February. Car is not "limping", though I certainly chose to drive it home less aggressively than usual. :)

Check your receipt paperwork to see how many quarts of ATF fluid was replaced and what type of fluid was replaced. i.e. Mazda MV, Castrol Import multi Vehicle, Valvoline Max Life multi-vehicle



If only 3 quarts was replaced you may have only received a drain and fill.


There is a small chance that a blockage in the transmission may trigger the error code.

"Tech notes When a transmission solenoid is malfunctioned, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is dirty, it's recommended to change the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a mechanical transmission failure and that the transmission will need to be rebuilt or replaced.

https://www.autocodes.com/p0778_mazda.html


https://www.mazda3forums.com/95-maintenance-care/331789-how-drain-flush-atf-fluid-atx-mazda-3-a.html
 

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Discussion Starter #12
Check your receipt paperwork to see how many quarts of ATF fluid was replaced and what type of fluid was replaced. i.e. Mazda MV, Castrol Import multi Vehicle, Valvoline Max Life multi-vehicle



If only 3 quarts was replaced you may have only received a drain and fill.


There is a small chance that a blockage in the transmission may trigger the error code.

"Tech notes When a transmission solenoid is malfunctioned, in most cases the problem is not the electrical part of the solenoid; the problem is foreign material obstructing the mechanical function of the solenoid or the flow of the fluid through the transmission valve body. If the transmission fluid is dirty, it's recommended to change the transmission fluid and if possible removing the transmission pan for further diagnosis. Excessive debris or metal particles on the transmission pan could be an indication that there is a mechanical transmission failure and that the transmission will need to be rebuilt or replaced.

https://www.autocodes.com/p0778_mazda.html


https://www.mazda3forums.com/95-maintenance-care/331789-how-drain-flush-atf-fluid-atx-mazda-3-a.html
We have gone way beyond this. The new TCM, upon visual inspection, looks like it may have fried internally, in less than 10K miles. The shop is having discussions by phone with Mazda Factory Techs in an attempt to find the actual problem, which would be causing it to fry TC Modules. Time will tell, but they say it may be ready by this coming Friday.
 

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We have gone way beyond this. The new TCM, upon visual inspection, looks like it may have fried internally, in less than 10K miles. The shop is having discussions by phone with Mazda Factory Techs in an attempt to find the actual problem, which would be causing it to fry TC Modules. Time will tell, but they say it may be ready by this coming Friday.
First of all, it's good to see you didn't give up on this forum, after your exchange with the idiot who (thankfully) was recently banned by the admin staff. I think that most of the regulars here were giving up on threads whenever he showed up with his act.

AFA the TCM, there have been prior reports of TCMs being cooked due to being located too close to engine heat. Here's one that talks about relocating the replacement TCM, in order to resolve the root cause. Perhaps you can discuss this with the shop doing the work.

https://www.mazda3forums.com/61-powertrain-2004-2009-mazda3/694033-check-engine-light-light-u0101-tcm-issue.html
 

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Discussion Starter #14
OK, problem has been resolved. Apparently it was "merely" dirty contacts causing the problem, and after the actual diagnostics, which involved cleaning the connections, there have been no problems as of two tanks of gas now. My Transmission Guy (The Transmission Physician) in Eustis wouldn't even take any money for doing it, since it was his opinion that he should have cleaned that the last time I had it in for a repair. I really tried to pay him at least a diagnostic fee, but he wouldn't take it, claiming that he really didn't do anything.

I figured it would be like a boat (acronym for Break Out Another Thousand), but we just had to do without the car for a while was all.

Thanks for your support. :)
 

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Glad to read your issue is resolved with no extra expanse, and also that you have such a good shop to work with! And thanks for potentially helping others by following up with your outcome - most never do.
 

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Glad to read your issue is resolved with no extra expanse, and also that you have such a good shop to work with! And thanks for potentially helping others by following up with your outcome - most never do.
Yes, I try to share the outcome, as it truly is a benefit to others, as well as being a sign of respect. I don't just come in here to take. I sure do like driving that car when it is right.
 

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Yes, I try to share the outcome, as it truly is a benefit to others, as well as being a sign of respect. I don't just come in here to take. I sure do like driving that car when it is right.
This was an interesting issue which I, for one, am glad you addressed and kept current. One of the frustrating parts about automotive forums is when someone comes along with a problem and there are several pages of posts filled with back and forth where people help the OP as the OP responds with actions taken. Then, the OP will end the thread something like this, "Hey everyone. I found the cause of the problem and my car runs great!! Thanks to everyone who helped." without explaining what the fix was. To top it off, there will be further posts from others asking what the fix was; however, the OP vanishes.
 
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