Mazda3- Headlight pulse on downshift.

ItAintRodKnock

Veteran Member
Joined
Sep 29, 2008
Location
Fraggle Rock, CO
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01GolfTDi
So, my sisters car is doing something that i do not understand. Also, dont know much about her car in general...

Anyways, its a 2013 Mazda 3, 6 speed tranny.
I drove it tonight to bowling league and noticed when i downshift coming to a stop or maintaining speed on a hill the headlights pulse. Dim, Go back to normal, Dim, go back to normal. Not a strobe, but maybe half second intervals.
Running the AC(for more power draw) made no change in the interval rate, or the lumen output of this pulse.

She says she's noticed it for awhile. So, its not new, and she has not recognized any other electrical quirks. The battery is new, Alternator is, assuming, Original.

Any ideas?
I doubt ill be digging into the car to diagnose, but if it turns out to be fairly common, then maybe I'd tackle it.

Thanks for any inputs!
 

oilhammer

Certified Volkswagen Nut & Vendor
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Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Which engine is it ? There are three. The Ford derived 2.0L (Mazda calls it MZR, Ford calls it Duratec), the 2.5L version of that same Ford engine, or the Mazda Skyactiv 2.0L.

The charging system is likely the same for all of them, though. The ECU should control the charging output of the alternator. I would also want to make certain that the battery is the correct type and size for the car.

But it may just be a normal quirk of that particular car. There was a TSB for some about PCM reflashing, not sure if it applies to that car though.

Search for this:

TSB: 01-13-21
2012-2013 MAZDA3 - HEADLIGHTS FLICKER WHEN BRAKES ARE APPLIED
APPLICABLE MODEL(S)/VINS
2012-2013 Mazda3 vehicles (with SKYACTIV-G 2.0L and Halogen Type Headlights)

Chances are there have probably been a half dozen software updates for that car since it left the factory anyway.
 

ItAintRodKnock

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Location
Fraggle Rock, CO
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01GolfTDi
I think it is the 2.5 i will to confirm

Battery: with the cold she started having issues, so i went to oreillys, he pulled up all the different ones the comp says are good for that car and i purchased the highest rating one. so, hopefully it the right size.. I'll look into specs for the proper battery and which one i did purchase her.
I'll figure out what motor for sure.

Assume you looked it up through google or another forum? thanks for taking that time, oilhammer.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Alldata and MOD are my primary resources. But the internet also may net some information.

A reflash may be the ticket. After Mazda's split with Ford, we can no longer do those here, although I think they still use a version of Ford's IDS software at least on something like that. That car is essentially a Focus that Mazda assembled, with a few of their own locally sourced bits.
 

garreth5

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Jan 25, 2015
Location
GA
TDI
jetta
This should fix your sister's car-- mazda3revolution.com/forums/2010-2013-mazda-3-skyactiv-discussion/43697-pulsing-headlights-tsb-13-21-a.html
 
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