Mazda3 battery replacement (hidden surprise)

blondee_yvr

Member
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2012 Mazda3
I've been watching several YouTube videos and written instructions. Only but a couple ever mentioning running into a situation where your vehicle memory settings like radio and computer are lost.

I came across this link which scares me with procedure #1.

Based on the videos I seen, I take it most people never bother to clean their battery terminals. I never did the first time I replaced my battery in my 05 Mazda and I had no issue, but subsequent times when I went to do some battery maintenance I ran into the throttle body/rough-idle issue.

Here is the procedure below:
If you replace the battery or clean the electronic throttle body on a Mazda 2.5L engine, you must perform a Mazda throttle body relearn procedure to teach the computer a new “home” position. It’s not hard. Just follow these steps in exact order.

To do a Mazda throttle body relearn procedure

1. Perform a hard PCM reset by disconnecting the battery cables from the battery and touching them together. This will drain the capacitors in the PCM to wipe out adaptive memory.


2. Reconnect the battery and turn the key on but do not start the engine. Immediately depress the throttle to the floor (wide open throttle) 3 times. This will set the TPS angle.

3. Start the engine with no loads on (no lights, blower, defroster, etc) and allow it to come up to full operating temperature (wait for the radiator fans to come on.

4. Then add loads to the engine by turning on lights, AC, brake application, steering input, one at a time.

This will cause engine load and the throttle body will open to compensate for the increased load. The throttle body relearn is now done.
 
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2014 Mazda3 S GT auto, 2008 MX5 6-speed
Is this in your owner's manual? I have not yet replaced batteries in my 3, as it has the i-ELOOP battery and super capacitor. The dealership does do some resets after installation.
 

blondee_yvr

Member
:
2012 Mazda3
Is this in your owner's manual? I have not yet replaced batteries in my 3, as it has the i-ELOOP battery and super capacitor. The dealership does do some resets after installation.
Concept, unfortunately not. I experienced the throttle bottle/engine idle issue the "hard way". What's interesting is the first time I swapped the battery, I did so within about 10 seconds. There was no issue. Then I thought to myself i should clean the battery terminals and the new battery posts, apply some battery grease, and felt battery pads. I suspect the resistors et al had enough juice to retain the battery info for a very short period of time.

After, I disconnected the battery. Everything was dead, and it took a few days of extremely rough idling at stop or red lights where it seemed my engine would fall out.

I had to do some research on the actual process. Some YouTubers refused to acknowledge this issue and they filtered (censored) posts with the procedure I posted above. Only good vibes and positive comments or "user blaming" were allowed. I thought I would post here for archival purposes.
 
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2014 Mazda3 S GT auto, 2008 MX5 6-speed
Thanks for the link. My son has a 2012 Mazda 3 hatch with Skyactive and he has replaced his battery a few time without any issues. The first time he did it I loaned him by terminal wire brush cleaners and anti-corrosion spray. Did you get any codes when your engine was running rough?

In the past, I have purchased a factory service manual. One of the nice things about such a manual is that you can see if any special tools are required, and if a specific sequence of disassembly is recommended.
 

Tribe&TrueRacin

Member
Banned
:
Mazda
WOW.. ok the best advice having sold and installed literally over 5000 batteries , if you have any questions about any vehicle you own regarding a battery change DONT USE DIY information on the internet or forums, rather seek exactly what the FSM=Factory Service Manual procedure is.

I read on this thread perhaps the best wording is misconceptions (MYTHS) of what a MAZDA ECU does and is capable of doing

On most OBDII ECU vehicles and almost ALL MAZDA gasoline model engines manufactured from about 2004 and newer once you have at least 4 complete engine cycles (starting driving stopping next day repeat) the power training control from the ECU will have completely re-set the monitors and the general drivability functions. If there is any engine function not withing normal operating perimeters, you will get a DTC indicating something that may need to be addressed. This is very rare when changing a battery on any but some model diesels, Hybrids and full electric vehicles.