Turn signal hyper flashing?

ELLENHAM

MEMBER
2009 CHEVROLET IMPALA
3.5L
6 CYL
2WD
AUTOMATIC
198,000 MILES

A few weeks ago, before I installed new front headlight assemblies, the front passenger turn signal began to hyper flash, indicating a turn signal bulb malfunction. Replaced the bulb with the correct replacement bulb but still no blinker, but now both the front passenger and front driver side blinkers hyper flash. Checked and replaced both fuses but nothing improved. Flashers appear to be working fine. I had a couple people look at, especially my brother who is an ASE Certified tech and works for the PA State Police. He said it is probably a wiring problem, a relay issue, or the Control Module under the left side dash. What questions do you have for me, and what is your opinion? I took it in today to a local retail automotive shop who did nothing but run a diagnostic test for $85. Now the blinkers work but only hyper flash. And when I left the shop, I was unable to reverse my driver's seat with the electronic button on the left side of the seat, therefore, I was stuck driving my car with my butt on the tip of the seat. Now I'm home having a glass of wine soothing my frustrations.

5 Replies

MATHGEN

MECHANIC
128 POSTS

Hello, sorry to hear you are having these problems. When you operate the turn signals, is it the exterior bulbs that flash fast or just the indicators in the instrument cluster? Also, do the front and rear bulbs illuminate? Another thing I would like to know is if the hazards work normally. As far as the seat goes, I think that is a separate issue as the seat switch is wired to the adjustment motors. You might look under the seat to see if something is blocking the seat from moving. Hopefully we can get this figured out for you.

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Thursday, July 20th, 2023 AT 5:13 AM

ELLENHAM

MEMBER
3 POSTS

1 and 2. Both interior and exterior lights flash but it appears the exterior front lights are dimmer. 3. Hazards work normally. 4. Yes, seat is a separate issue. I have been advised to replace the multifunction switch (turn signal mechanism) on the steering column.

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Thursday, July 20th, 2023 AT 8:45 AM

MATHGEN

MECHANIC
128 POSTS

Sorry for the delayed reply, but I have been studying your issue for a while. I'm not convinced that replacing the multifunction switch will fix the problem. Basically, the switch sends the signal to the Body Control Module, the BCM then uses an internal processor to cycle the appropriate lamp. With the hazard function working normally, all bulbs light up bright and flash normally, that makes me think that the wiring, sockets and bulbs are ok. So, I am thinking you may have a BCM issue. There is no schematic, but I am sure that it uses separate drivers for the hazard function and the turn signal functions even though they share the same exterior wiring. I hope this isn't too confusing. But I would look for any loose or corroded connectors first and then look into having the BCM replaced.

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Friday, July 21st, 2023 AT 4:38 PM

ELLENHAM