Author Topic: Strange electrical fault!  (Read 214 times)

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Offline danimerebean

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Strange electrical fault!
« on: September 07, 2017, 07:44:56 PM »
Hi guys!

Got a really odd issue that i'm hoping someone may have come across before.

My car is a 2013 1.6 Mazda 3 Tamura, bought the car privately in April. 2 months later the fault started developing.
The car seemed to struggle on full lock when parking on a drive or supermarket etc. The headlights would flicker and the radio would stutter or maybe reset to the 'Hello' screen as seen when first started. This would happen very rarely and would not happen on demand to demonstrate.
The next symptom is once the car is warm (ie blue icon gone out), when driving on a dual carriageway/motorway with the headlamps on and you indicate to change lane the headlamps will flicker and dim in time with the indicators. The headlamps also dim very momentarily when you apply the foot brake. Sometimes when flashing main beam the instrument lights will light up like a tree and the car will cough but then continue as if nothing has happened! This sometimes also happens when turning the headlamps on while driving.
This has gone a while sporadically but has now got more frequent.
I have drop tested the battery and it passed no problem.
I have checked the alternator output with headlamps on, 12v socket occupied, air con on - 14.5v at idle and 3000rpm
I have checked every earth i can find, even added a thick new one from battery to gearbox!
I had the car diagnostically scanned - It showed battery low voltage, battery high voltage, EC Relay fault code.
Bought a new relay from Mazda - still no joy!

If anyone can suggest a check or share any wisdom i would very much appreciate it!

Offline Willpower

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Re: Strange electrical fault!
« Reply #1 on: September 07, 2017, 08:10:24 PM »
Although you say you have checked already, all the symptoms you have are classic earthing problems.  I would suggest revisiting your steps investigating the earthing strips and connections.  Make sure that you have a clean metal to metal connection.
 
Look at life through the windscreen, not the rearview mirror.
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Offline danimerebean

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Re: Strange electrical fault!
« Reply #2 on: September 07, 2017, 08:22:17 PM »
I've been over the more obvious things like that today after fitting the new relay.

I have just read on a US forum there was a PCM software update for 2013 models presenting with flickering headlights when applying foot brake. Going to give Mazda a call tomorrow to book in for the boot hinge re-call and see what they say about the PCM software.

Fingers Crossed!!!

Offline StevenRB45

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Re: Strange electrical fault!
« Reply #3 on: September 07, 2017, 08:52:16 PM »
Have you tried another battery? I know you said you tested it but what you are describing sounds like the voltage is dropping so low when you combine the load of lights and the power steering pump the dash thinks the cars switched off then on again (hence the hello).

Offline speedy mazda

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Re: Strange electrical fault!
« Reply #4 on: September 07, 2017, 10:31:24 PM »
I was going to suggest the same steven sounds like  a battery problem  ,is it the original battery ? my lights always dimmed with the  power steering with the original mazda battery.

Offline moozmooz

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Re: Strange electrical fault!
« Reply #5 on: September 08, 2017, 08:34:19 PM »
Almost certainly a voltage regulator problem. The alternator output isn't keeping up with demand as fast as it should.


Offline hanix

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Re: Strange electrical fault!
« Reply #6 on: September 09, 2017, 09:31:44 AM »
I would think the cheap first option is swap the battery for a known good one. Batteries and car software are sometimes strange bedfellows. (Try owning a Jaguar).

Offline danimerebean

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Re: Strange electrical fault!
« Reply #7 on: September 11, 2017, 09:34:07 PM »
Thanks for all the replies guys.

I checked with Mazda UK Technical dept about the PCM update and was as good as stonewalled.
Spoke to a local independent Mazda specialist today and the guy pretty much guaranteed its a Body Control Module fault. Very common apparently. Its a main dealer only job because it needs to be coded - typical.

Tried something new tonight - Reset the ECU, the still with the battery disconnected, removed the BCM. Cleaned all the multi plug pins on the loom and BCM and refitted. Took it for a 1/2 spin when it was dark with main beam, A/C and radio blasting and so far NO FAULTS. Whether this is luck or a fix remains to be seen.

I'll post any updates if it goes sour!

Mazda 3 Forums UK

Re: Strange electrical fault!
« Reply #7 on: September 11, 2017, 09:34:07 PM »