My C5 (58k miles) started doing some strange things the last two days. Let me preface by saying I have all LED lights and a hyperflash harness installed by Sharp Light Innovations,

Normally the corner daytime running lights/marker lights would not turn on until I put the handbrake down for the first time after turning the car on. Two days ago I turned the car on and they were already on, handbrake still engaged. Today I go for an evening drive, that issue doesn't happen again. The turn signals work while the lights are off, but I notice the HVAC buttons are all flashing along with the turn signals at the same rate. The hazards are also flashing at the same rate as the turn signal (not hyperflashing like they've always done which I thought was strange). I go to turn on the fog lights/side marker lights and my turn signals are illuminated on the dash solid and not flashing. Hazards also not working. I go one more notch on the stalk and flip up the headlights, same issue.

Not sure if this is related to the hyperflash harness? Not sure why the hazards all of the sudden are not hyperflashing anymore, as I understand the harness fixes the turn signal flash rate but not the hazards. Ground issue?

Here is an attached video showing the issue:

You Tube

As as a side note, for a while now while unlocking the car, the driver side mirror goes haywire and re-adjusts itself or when hitting the memory button about 80% of the time. Not sure if that's related at all to the above issue.

 

you might be right on the ground issue, I would take a close look at that. Dash lights and turn signals use the same ground I believe. Take a good look at the harness you installed and see if the connections look good.

 

So far I cleaned the ground and ground boxes behind the headlights and underneath the battery which seems to be a main one for the computer. So far still nothing. Those were all the ones in the engine bay and they looked pretty clean. The only other ground that looked related at all to the lights was inside the driver side footwell area it seems.

 

A wiring diagram might be a help. Some of the aftermarket Corvette suppliers have them.

 

I would contact the Sharp light Innovations guys and see what they say. It's definitely feeding back for some reason. Might need to make a warranty adjustment.

 

Contacted Sharp Light Innovations, they mentioned this sounds like a common issue on C5's with the 'Multifunction Switch". I did some reading and this seems to cause issues more so with the pop up headlights and turn signals not working at ALL. I removed the hyperflash harness and it seems that did nothing, same issues present still. I also checked the fuses under the hood and they all looked fine. A little stumped where to go from here.

 

Dropping this in here in case this helps narrow down the issue. I used the onboard diagnostics mode and found these codes:
BCM-
B2578 H
B2583 H

IPC-
U1088H

A0-LDCM
B2282H
B2284H
B2264H

A1-RDCM
B2283H
B2285H

I am currently in the process of looking this all up to see if this narrows down a problem area.

 

Well so much for an easy fix. Have you tried different flashers? A different brand maybe? LEDs are fussy at times with bulbs and flashers. Try swapping Led bulbs and see if that makes a difference. I have had issues on older GMC swapping to LEDs flashers and bulbs. Swap bulbs with the stock bulbs and see what happens And start over again. something is not compatable.

 

What's strange is that I've had these LED's in my car for about 4 years now and never had an issue. And all of the LED's still work fine so it's not like I have a bad bulb?

 

That's a lot of codes. Maybe they will mean something.