# Hyper-flashing Turn Signal Blues



## Tomko (Jun 1, 2013)

Bad filaments?


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## Blasirl (Mar 31, 2015)

Tomko said:


> Bad filaments?


That might answer part of the issue, but both over two days dying and the other functions still working. Why?


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## carbon02 (Feb 25, 2011)

I don't know on Cruze but on other late 200o's GM's the flashers are controlled by the hazard switch. I don't know in a Cruze if that's the same strategy or if they are directly controlling them over the BCM.

First try replacing with factory bulbs at least to test the situation. The LED's don't have the same resistance as a filament bulb, and the art of most flasher circuits rely on a minimum resistance.


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## ChevyGuy (Dec 13, 2014)

The BCM is the "flasher". It will hyper flash if the current draw is too low. I'd start simple - replace the bulbs.


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## 91794 (Mar 25, 2015)

Swap in a new fully charged battery.


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## Blasirl (Mar 31, 2015)

carbon02 said:


> I don't know on Cruze but on other late 200o's GM's the flashers are controlled by the hazard switch. I don't know in a Cruze if that's the same strategy or if they are directly controlling them over the BCM.
> 
> First try replacing with factory bulbs at least to test the situation. The LED's don't have the same resistance as a filament bulb, and the art of most flasher circuits rely on a minimum resistance.





ChevyGuy said:


> The BCM is the "flasher". It will hyper flash if the current draw is too low. I'd start simple - replace the bulbs.



I went last night and purchased two turn signal lamps to do just that. This morning when I got to work I left the car running and now I have no outer tail lights either. No turn signals in the back or flashers. My third brake light works as I can see that when I step on the brake and the inner tails work. The reverse lights work and they are the only LEDs.

I am going to see if I can swap a lamp during lunch today.



eli said:


> Swap in a new fully charged battery.


Why?


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## Taxman (Aug 10, 2017)

Bad tail lamp ground?


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## snowwy66 (Nov 5, 2017)

Usually when they flash fast. One of the bulbs is burned out. Either front or back. 

You did a walk around to check both front and back?

There used to be one relay for flashers and one for turns. Don't know how its done these days.


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## ChevyGuy (Dec 13, 2014)

Taxman said:


> Bad tail lamp ground?


That would explain a lot. The turn signal may appear to work due to current flowing though the turn signal filament, though the tail light filament and then though another parallel filament (in another lamp) on the way to ground. But I doubt if the BCM is going to as accommodating to allow tail light current to flow though the turn signal. While current does flow and the light does light, it's not the normal brightness - or the normal current. That would trigger the hyper flash.

At this point, I'd focus on the tail lights and get them fixed. I think it would be easier to track without the red herrings that turn signals can give you.


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## Blasirl (Mar 31, 2015)

Well, I really appreciate all the brainstorming. A number of these things is what I would normally think of, but I forgot about the "I'm getting early onset oldtimers' theory.

I purchased the new lamps as I said before and did not get to them until after work yesterday. I waqs really getting worried as I posted last week sometime I tried for the third time to get my aftermarket tails to work - hurriedly. 

Well I first retested all the functions that one can do without help or a mirror. I walked around the car and looked at every light in all the different states and both left and right rear body tails were not functioning at all. I pulled out the drivers tail and removed the turn signal lamp and tried to get a resistance reading across the filament, but was getting some wildly swinging readings. Me, being somewhat thrifty - my wife says cheap, but I digress - I thought, I made an inexpensive test rig from a 12v drill battery, why not try that first.

I clipped to the lamp and lo and behold, it works, as did all of the other lamps. I then started to suspect my Curt trailer wiring as it is installed between the factory harness and the tails on both sides. I used my HF test lamp and both turn signals as well as the flashers worked.

WTF! Well, beer thirty came and went and I still had no idea what was wrong. I used arm signals for the past three days and was starting to think about upgrading to a 2019 Cruze, but then i thought of all the upgrades I had done over the last three years that would not work on a Gen II.... 

Time to pull up the boot straps and re-rip apart the trunk. I did not even get the drivers side cover partway out when 









Stupid me ... they really do work better when they're plugged in!


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## Tomko (Jun 1, 2013)

https://www.cruzetalk.com/forum/17-off-topic-discussion/206458-stupid-car-tricks.html

and @*brian v* gooferballer trophy nominee.


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