I have same problem on my 2006 mazda 3. I am very close to buying the new TCM but I also would love to hear if after all this time the problem is still solved.

Also, someone mentioned about RPM-s jumping when in 5th gear. What is it? Is is override (6th gear) or a problem?

 

Since changing the TCM, I have had not a single issue since. It worked

 

Hi kristel

I just happend the same issue recenlty with my mazda 2010 and is been in dealership for 2months waiting for the parts import from japan. It happend with the fault code of U0101. Tried to solve with all kinds of way but now decided to replace TCM and i hope this will solve and get back my baby.

 

Im having the same issue with my mazda 3 2.3L 2008. I changed the front passenger mount cause the old ones rubber was literally sliced in half. Also changed the transmission fluid. The car still jerks on reverse. When I drove it for 1 block, it never passed 2000 rpm. I cant see what gear its it on the dashboard. Do i just need to replace the tcm or also the shift solenoids? Please let me know.

 

Hey guys,i had a 2010 mazda 3 2.0 5 D with 106000km. I had the same occurrence on monday. I was driving 100km/h highway,all the sudden, I lost the speed down to 80km/h.I believed that the gear must have shifted down. It felt like I hit something.The AT light poped up and disappeared. The next time I started the engine, the CEL and AT light both poped up. I only could drive under 3rd gear. Eventually,I had to call a tow truck to a dealer. The dealer had it check with the scanner. The diagnosis of the u0101 error code was found. The mechanic suggested to replace the TCM, so I did. It worked so far with 10km drive. I haven't try it on the highway yet.I just can't understand based on my car mileage,what would be the cause of the malfunction of tcm? It doesn't makw sense to me. Can the scanner detect the malfunction of the harness?That would be the different error code?

 

Hungbryan:

I have a 2007 Mazda 3s automatic (132k). What you describe is what is happening to me also. Driving at 70mph on the freeway and it feels like I hit something and the AT light blinks and then quickly goes out. I have taken it to 2 different Mazda dealerships and the computer is storing no codes for them to pull. All the threads from the pass makes me think it's the TCM so I wanted to check and see if your problem has happened since changing it?

 

Hi,I got my brand new TCM replaced for a month. I have driven for almost 2000K both on highway and city.highway mostly.
The gear shifted alright,but I think the trany has re-learned. The timing of the gear shifting has changed compare to the past. It's not as smart as before. Maybe it needs more time to learn from my driving pattern.
Also, I noticed the sound of engine is greater. I am not so sure it's correlated with the damage of gearbox or not.
After all, the malfunction has fixed.

 

Glad you got it sorted out, bryan

 

Hi Guys,

Newbie here. I have a 2008 Mazda AT 1.3.

Just wanted to ask if I have the same issue as this thread talks about, here are my 3 issues that are currently occurring to my m3.

1. When I'm at the highway, I'm running at 80km/h riding in 2000RPM under D-4th gear (4th gear is the max for my m3). When I tried slowing down and accelerating again, the RPM surges to 3000 to 4000RPM while the dropping into 2nd Gear. This symptom is quite new to me since I own the car since 2008.

2. When I'm in stop, I noticed that the rpm surges when I put it on Neutral or Park mode without stepping the gas. When I put it back on Drive mode, it becomes normal.

3. Shift lights (1, 2, 3, 4) sometimes goes of for 30 secs to 1 min. And it will just come back normally.

What could be the issue here? Thank you guys for all the support. It's been bothering me for months now, and I just recently joined this thread because it seems like i'm having the same difficulty with the same issue.

 

Hi All,

A similar scenario happened with my 2007 2.3 liter 3 with 126K miles on it back in November. Out of nowhere, the car dropped to 3rd gear on the freeway and wouldn't shift out. I got the car towed to the dealer and while I waited for the tow, I read similar stories on this forum and others about the transmission control module needing to be replaced.

As soon as I got to the dealer and drove it off the flat bed, the CEL and AT light went off. Of course! The service manager agreed to keep it for the day and put some miles on it to see what happened next. As soon as the moved it out of the garage the AT light came back on and the car got stuck in 3rd. They pulled the code (P0753 - shift solenoid). Based on their experience with this vintage, they were already pretty certain what needed to be done. After discussion, I agreed to have them re-program the TCM before replacing to see if they could bypass a software glitch. AT came back almost immediately. After authorizing replacement of the TCM, I've had the car back for 4 months and have had no problems.

Expensive, but, seems to have been the only way.

Side note - Consumer Reports ratings on used cars highlights that the 2007 had trouble spots in transmission (minor) and suspension. I've found this to be spot on.

 

Mine is currently at Mazda dealership waiting for TCM part to arrive. Thankful that I bought the maxcare service plan when I purchased vehicle from Carmax, whole repair will cost me only $50, that includes loaner vehicle.

 

Good you got it fixed drive like that will muss it up your car only as good as you treat it

 

Hi there,
My 2007 Mazda 3 SP23 jumped into 3rd and AT light came on. Took it to transmission guy who advised that everything mechanically and wiring etc was okay and concluded it could only be the computer. I agreed to put a second hand one in as he couldnt give me a guarantee this would fix it. All up for this and his work i paid $AU1300. The problem came back almost immediately although this time it would come and go whereas previously it was stuck with AT fault. So the change of TCM had made some kind of difference. I took it to Mazda who went over everything and came up with same conclusion that it could only be the TCM which would be around $1800 brand new. After a few months of the car mostly driving fine albeit the engine warning light stayed on but no AT fault, or when it did come on it would reset okay, it has now gone back to the fault being there full time. So i now have the dilema of whether to go with a new TCM as the car is useless otherwise. My nagging doubt is that the second hand TCM never worked. Did i just get burned with the second hand one not being good enough and new one will work okay? Would appreciate any feedback/advice from anyone who has experienced a problem with a second hand TCM.

 

Did you ever find out what the problem was, as my 2007 Mazda 3 is now acting the same I'd be in 5th and it throws it down to 4th with at light coming on?

 

Mazda People,

If you are having these issues with CEL+AT light and auto trans dropping to 3rd with solenoid error codes or Uxxx codes it is almost definitely the TCM (transmission control module). DO NOT pay thousands to the dealer for a transmission replacement. It will likely not help.

I recently had same issue on my 2007 Mazda3. Dealer told me replace trans for $4k. I took car home to troubleshoot. Replaced TCM for $300 and problem solved!

The Mazda TCMs are designed poorly. They mount directly to the transmission and electronics possibly suffer thermal damage from the trans housing. There are 5 versions now. Your car probably has L34T-18-9E1A. The newest rev is L34T-18-9E1E. The only difference is probably the software. They are very simple to replace yourself and save tons of money.

Here’s what to do:

1) First go around your engine and check any electrical connections to make sure they are all seated properly, nothing loose, and no fuses blown. You may also want to check harness connectors to the ECU under the passenger floor. Also make sure all vehicle ground harness is tightly secured to the chassis. These are usually thick black cables bolted to the frame. It’s unlikely any of this is the problem but it’s the simplest thing to check first.
2) Buy a OBDII code reader. Something like this.
3) Read your error codes.
4) If you have any of these then replace your TCM.
• Uxxx – network code loss of communication with TCM or ECU
• P0753 – shift solenoid A malfunction
• P0758 – shift solenoid B malfunction
• P0763 – shift solenoid C malfunction
5) You can buy an improved refurbished TCM for $300 here. This is what I did. Or buy from Mazda part number L34T-18-9E1E. Dealers charge about $500+.
6) Install yourself like . Or get a friend to help.

There are other less likely issues that can cause similar trans problems. If replacing TCM doesn’t solve your problem or you have different error codes than what I’ve listed then replace these sensors on top of your transmission. These are all located near the TCM:

1. Vehicle speed sensor, FN0121550 (also called speed pulse generator, transmission output shaft speed sensor)
2. Range Sensor, FN0221444 (also called auto trans gear position sensor, neutral safety switch)
3. Speedometer sensor, FN1221551A (also called vehicle speed sensor)

If after all this if you still have a problem then you could consider replacing the actual shift solenoids in the transmission or the transmission itself as a last resort. Only at this point would I consider the transmission at fault.

Good luck!