PCM reflash advice for strange electrical faults
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PCM reflash advice for strange electrical faults
I am hoping someone may be able to help me get to the bottom of my issue! I have a 2016 Mazda 2 1.5 Skyactiv and it has some strange problems going on! I am based in the UK.
The main problem is with the odometer display, in that it keeps switching itself on and off, there is no rhyme or reason to it, it is very much an intermittent fault, along with this the battery mgmt. system will also occasionally display a fault causing the i-stop to not work and start to flash. This occasionally seems to sort itself out when the engine is turned off and restarted.
I have had the car looked at by an auto electrician and this has baffled him too, there are no fault codes, and battery is running as it should, he has suggested a PCM reflash as this may solve the issue (but again is not sure). I have contacted the main dealership and they have quoted their hourly rate, but in the next breath said this is if we don't find any other issues. I have had such bad experiences in the past with mechanics and garages that this was a big red flag to me unfortunately.
Has anyone else similar issues with this type of problem, and if so what was the fix?! Also is a PCM reflash something that can only be done at a Mazda dealership or is it something that I could get done independently?
Any advice would be most greatly appreciated.
The main problem is with the odometer display, in that it keeps switching itself on and off, there is no rhyme or reason to it, it is very much an intermittent fault, along with this the battery mgmt. system will also occasionally display a fault causing the i-stop to not work and start to flash. This occasionally seems to sort itself out when the engine is turned off and restarted.
I have had the car looked at by an auto electrician and this has baffled him too, there are no fault codes, and battery is running as it should, he has suggested a PCM reflash as this may solve the issue (but again is not sure). I have contacted the main dealership and they have quoted their hourly rate, but in the next breath said this is if we don't find any other issues. I have had such bad experiences in the past with mechanics and garages that this was a big red flag to me unfortunately.
Has anyone else similar issues with this type of problem, and if so what was the fix?! Also is a PCM reflash something that can only be done at a Mazda dealership or is it something that I could get done independently?
Any advice would be most greatly appreciated.
Senior Member
Joined: Oct 2018
Posts: 10,664
Likes: 233
From: Northern California
First I can’t say about service work in your country.
The battery needs to be (should have first been) load tested.
The battery cables and the 2 main cable condition areas should be checked and possibly cleaned.
The ECU needs to by properly and (completely) scanned. Which by your response was not. Your description of problem there would
have been something found.
A ECU flash is never a bad idea. A shop that has a pass-through or similar equipment can perform a PCM/ECU flash. But you would
need to contact the shop in advance ask them and have your VIN ready.
It’s late I not at work lol, so can’t access your model Mazda info, but Your BCM may also be causing your issue. If so it’s a simple service replacement most DIY can do. The auto electrician should have tried to check that?
An auto electrician that can’t find an electrical issue which this is not every experienced.
The battery needs to be (should have first been) load tested.
The battery cables and the 2 main cable condition areas should be checked and possibly cleaned.
The ECU needs to by properly and (completely) scanned. Which by your response was not. Your description of problem there would
have been something found.
A ECU flash is never a bad idea. A shop that has a pass-through or similar equipment can perform a PCM/ECU flash. But you would
need to contact the shop in advance ask them and have your VIN ready.
It’s late I not at work lol, so can’t access your model Mazda info, but Your BCM may also be causing your issue. If so it’s a simple service replacement most DIY can do. The auto electrician should have tried to check that?
An auto electrician that can’t find an electrical issue which this is not every experienced.
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