Batboard

Hello. I just installed a sho-me model 03.W3041 ground switching headlight flasher in my 2004 Chevy Imapla. Did the relay to disable the DRL's and all. Works great - EXCEPT: While and after the flasher is on, the "service Engine soon" light comes on and says check headlights. Is there any way to overcome this??

thanks!

Hi Jay.

Is this a police package (option code 9C1) or a civilian model? If it is the civilian model, I would STRONGLY reccomend removing the flashers from this vehicle. Chevrolet does'nt reccomend any modification to the lighting system of this vehicle as it will cause computer and electrical problems such as you are experiencing. Your best bet is to probably put a pair of clear strobes in the headlights if you require clear alternating flashes.

Ive installed numerous flashers in Civilian Impalas. I have yet to have any problems. Im thinking its the flasher or a wrong hook up. One of the few approved flashers is made by Sound-off.

Jay are you sure you have the DLR wire. It has to be taken at the plug just behind the battery.

I went over it 5 times. All hooked up 100% correctly. DRL wire also. This is the second car I've had this issue with...

thanks!

My Impala 9C1 even did that too.... But not all the time

I heard it's a problem with the 2001's and they fixed it in 2002 +

I don't know what "method" you used to install this flasher, but I would highly recommend removing it. The Sound-Off flasher for the Impala is the only flasher approved by Chevrolet. The DRL's and headlights are controlled by the BCM on the car, and if your flasher is backfeeding into the BCM, you could cause serious damage to the car's systems. I would take out the cobbled together system that you installed, and do it the right way.

Mike F

Your problem is the flasher. You need to get the Sound-off unit or the Whelen. You cannot fool the BCM in this car. The Sho-Me GSS flasher won't do the trick. The DRL circuit is a 2 relay setup (3 if you count the high beam relay) designed to collapse and fail safe.

Even with the civilian Impala, wiring in one of the approved flashers shouldn't fire the SVS light. I've done a handfull, and never had a problem. I much rather prefer the 9Cx's with the plug and play harness, as I'm sure ya'll do also.

I've always disconnected the battery to prevent frying the BCM while doing this, so when the power is replaced there are no codes set. If you try and "test" the install before complete, you'll set a SVS light. The reason the SVS light stays on after you use the flasher is due to the BCM still thinking the DRL circuit is screwed.


The Impala BCM is the weakest item in the car. Mine just got replaced after 44k miles because it started freaking out and -nothing- controlled by the BCM worked. Thanks GM for that wonderful design.

Oh yeah, the BCM is made by none other than Ma /\/\ herself