p0647 on startup???

[Kappa9012]

Anybody ever see this before? seems to do it when I remote start the truck, but not all the time. Seems like if its been sitting for awhile it will pop the code when I use the remote.

It just started about a week ago and i'm wondering if it's related to me washing the engine bay???

 

[Kappa9012]

N/M it's not just on startup... After some poking around I found the code is for the A/C relay, short to ground.

it happens with the remote, i assume, becuase it cycles the A/C compressor on to load the engine during the cold weather. I also tried kicking the A/C on and the light just flashes, but no code pops.

I'll run the troubleshooting for the relay/wiring and see if I can figure out what's wrong.

 

[alex17young]

That's a bad #8 glow plug, my v2 said the same code. Replaced the glow plug, my trucks been cel for 2 weeks now.

 

[alex17young]

*CEL free

 

[chevyburnout1]

That is not a glow plug code.

It could be related to pressure washing under the hood. Easiest thing to try first is to swap relays and see if anything changes. The code is saying the wiring circuit from the ECM to the A/C relay is shorted to ground constantly. The a/c compressor should not turn on if it's below freezing, but if it is then that further proves that wire is shorted.

 

[chevyburnout1]

Scratch that. I got my codes mixed up as well. That code is for the control circuit being stuck at HIGH voltage, aka when the ECM commands ground to the A/C relay it is still seeing battery voltage instead of being pulled down to zero. This is usually an indicator of a broken wire somewhere, or the possibility of a battery voltage wire shorted to the control circuit.

 

[stroke250]

there was an issue with EFIlive reading the correct codes. get another scanner on it and i bet it reads p0678. replace the glow plug nearest the driver side firewall(#8). problem will be solved.

 

[Kappa9012]

didn't get a chance to look at it tonight, but it does pop the code when using the key, so it may be the glow plug afterall.

 

[Kappa9012]

finally got some time and decent weather. #8 glow plug was bad, thanks for the heads up guys.