Having problems, even the dealership doesnt know

:
Cx 5 touring
I recently started driving my wifes 2016 mazda cx 5. The battery was dead, so i go to autozone to get a replacement. I suggest that we get a size 34 battery, the employee states that there shouldn't be any problem using the battery. As i go to install the new battery two things happen: first as i connect the negative terminal to the post it throws sparks like i connected on the wrong side, also the horn and headlights turn on. They tell me that i should try starting the vehicle, i do, to no avail, no power at all in the cab. Then i proceed to bring the battery back in and swap it for one on the list. Install is normal, but now all the car does is go into standby when pressing the pedal. No igniton. I suspect that the imobilizer is activated, so i do a hard reset. No change. I need some imput, the car is going to be towed by monday 1/7/19.
 
I recently started driving my wifes 2016 mazda cx 5. The battery was dead, so i go to autozone to get a replacement. I suggest that we get a size 34 battery, the employee states that there shouldn't be any problem using the battery. As i go to install the new battery two things happen: first as i connect the negative terminal to the post it throws sparks like i connected on the wrong side, also the horn and headlights turn on. They tell me that i should try starting the vehicle, i do, to no avail, no power at all in the cab. Then i proceed to bring the battery back in and swap it for one on the list. Install is normal, but now all the car does is go into standby when pressing the pedal. No igniton. I suspect that the imobilizer is activated, so i do a hard reset. No change. I need some imput, the car is going to be towed by monday 1/7/19.

First question, How did you know the original battery was dead?

Is it possible that the battery was fine, and that you instead have a failure of the brake pedal switch or the shifter P - interlock.
 
Last edited:
The battery was charged enough to get the car started and was also tested, however it didnt have enough juice. The car was also in park when all this work was being done
 
Ok... Thank you, trying to eliminate the two most common "failure to start" parts on the CX-5.

Next, perhaps examine all of the main fuses underhood.

What happens to the light on the START/STOP button when you press the brake pedal?
 
Ok... Thank you, trying to eliminate the two most common "failure to start" parts on the CX-5.

Next, perhaps examine all of the main fuses underhood.

What happens to the light on the START/STOP button when you press the brake pedal?

The button doesnt light up as per norm, generally when the key fob is touching the button it turns green, but theres no responce. As for the dash, the light is reading as green, so the keys chip is in the system.
 
You tried to install a Group 34 battery? Are you certain?

I checked a few parts sites quick and they all suggest group 35.

The posts on group 34 and 35 are reversed. 34 = left +, 35 = right +. If you tried to connect a battery with reversed posts without reversing the orientation of the cables to match the posts you may have done some electrical damage. Hopefully just some fuses, impossible to say without starting to go through it.

*Edit: unless he gave you a 34R to get the same post orientation as 35.
 
Last edited:
Thats not even something i had considered with the battery, feeling stupid. I will have to check the fuses, hopefuelly its that simple, and not the ecu or computer
 
Thats not even something i had considered with the battery, feeling stupid. I will have to check the fuses, hopefuelly its that simple, and not the ecu or computer
Firstly, you posted at the wrong section. Your question shouldn't be posted in How-To sub-forum.

Secondly, are you sure the new battery is group 34 as you insisted? Studum is correct CX-5 uses group 35 battery, and group 34 battery has positive and negative posts reversed.

Positive post is a little larger on diameter than negative post. Did you forced the terminals into the larger post? Did you double check you have red cabled terminal installed on the positive post of the battery marked with "+"?

If you installed wrong polarities to the new battery, a major damage can happen to many electronic modules, as indicated by the sparks when you installed the negative terminal.
 
I've replaced the main fuse block which was blown, but im getting tcm communication error, and when i go to turn over the engine im hearing a clicking coming from the transmission. Did i manage to fry my tcm?
 
Are you sure that clicking noise isn't the starter? The line that's going to the main fuse, the 200 Amp one I'm guessing, also goes to a 250 Amp fuse to the starter and charging circuits.
But if you did get the polarities crossed them you piped a few hundred amps through the ground side which isn't protected with fuses. Probably blew out a few control module units if you did, I'm guessing.
attachment.php
 

Attachments

  • juice.jpg
    juice.jpg
    124.7 KB · Views: 463
Last edited:
Sorry but I have lot of difficulty in believing that some one connects the batteri polarity wrong. It is well marked and it often leads to disaster if wrongly connected, we all know that. The polarity is the one and only thing that you have to concentrate on when connecting the new battery (after having checked the size and type before buying it). I hope it is some thing else that is the problem.
 
...reversed posts without reversing the orientation of the cables to match the posts you may have done some electrical damage. Hopefully just some fuses, impossible to say without starting to go through it.

Fuses don't care about polarity.
 
...
But if you did get the polarities crossed them you piped a few hundred amps through the ground side which isn't protected with fuses. ...

Please look up the definition of 'circuit'.
 
Sounds like a major screw up and the dealer wouldn't want to get involved because of many hours to correct and at high cost. Ed
 
Fuses don't care about polarity.

You're right. I was talking more about the various components in the control modules subjected to the sudden reverse bias, anything not protected would be blown.
 
Back