Turn Signals hyper-flashing?

Tiny
ALEXBUENA95
  • MEMBER
  • 2008 HONDA CIVIC
  • 1.8L
  • 4 CYL
  • 2WD
  • AUTOMATIC
  • 154,000 MILES
Both Rear turn signals and front driver side turn signal are in hyper flash. Front passenger turn signal does not work at all. Replaced all bulbs. No change. Checked for voltage in front passenger turn signal socket and there is no voltage to it. Hazards work at a regular flashing pace.
Tuesday, October 17th, 2023 AT 6:06 PM

1 Reply

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 108,279 POSTS
Hi,

If the flashers work, we can eliminate a possible ground-related issue. We know that a hyper flash indicated a faulty bulb/open circuit. The only light that doesn't get power is the right front, but that doesn't explain the left side hyper flash and the hazards all working.

I attached the wiring schematic below for this vehicle (4-door). I highlighted the power supply to the lights. The left (front and rear) gets power to the bulbs via a blue wire. The right side is via a brown wire. Since we know the hazard works, it can't be a wire from the fuse box. So, that leaves the signal switch (which doesn't make sense either because both right signal lights are activated via one wire from the switch.

That leaves the MICU (multiplex control unit). The MICU controls the turn signal/hazard flasher based on the input signals from the turn signal and hazard switches. It is combined with the under-dash fuse/relay box and is one of the B-CAN network components.

So, I suspect that is where the breakdown is coming from. Otherwise, there would be different issues. What needs to be done is the can-bus needs to be scanned. If there is a fault in the MICU, it should show up.

CAN stands for controller area network. Basically, the different modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module storing them. Again, I am recommending this based on the symptoms (hyper flash on the left with all lights functional and only one on the right with the front receiving no power).

Here is a link showing how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Let me know your thoughts. I attached the wiring schematic below and highlighted the relevant wiring so that you would have a reference. I had to cut the page in half to make it readable, but I did overlap them so you can follow from one to the next.

Let me know.

Joe

See pics below.
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Tuesday, October 17th, 2023 AT 8:09 PM

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