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2008 Avalanche LTZ Code P0650 Malfunction Indicator Light Control Circuit (Some MILs aren't lighting)

S

SNES Kirby's Avalanche

Full Member
Joined
Sep 23, 2020
Messages
92
Hey all,

Proud owner of a new to me 2008 Avalanche LTZ...2WD!

I used the forum to resolve P0449 already and now I'm getting the error P0650 Malfunction Indicator Light Control Circuit.

All of the gauges light when I turn the to Accessory with the exception of the following MILs:
  1. ABS
  2. OIL
  3. TOW
  4. Tire Air Pressure
  5. Check Engine Light
  6. BRAKE
  7. Traction Control
  8. Airbag

I'm hoping this is just a fuse but I have been unable to figure out which fuse I should replace?
 
Tried 46 (The instrument Cluster as a whole is working)

I just snapped a picture and I get the following when I move it to Accessory I'm getting:
  1. All gauges
  2. DIC
  3. PRND321
  4. Lock Icon
  5. BRAKE
  6. BATTERY
  7. AIRBAG
  8. SEATBELT
All the other MILs aren't coming online.
 
What are you using to test the fuses? Might as well check them all or anything related to control modules or the cluster while you are in there.
 
I FOUND IT!

Comparing fuses I found a few that were missing which seemed odd. The previous owner seems to have removed them, anyone know why?

48 AUX HVAC (this one fixed it!)
20 fuel pump
26 driver unlk 15A
 
Last edited:
Glad you got it fixed.

Sometimes, previous owners do us no favors.
 
How in the world did the truck even run if the fuel pump fuse was missing? ???
 
That means someone re-wired fuel pump on truck and I wonder what else.....

These are the used cars/trucks that scare me when previous owners re-wire stuff
 
ygmn said:
That means someone re-wired fuel pump on truck and I wonder what else.....

These are the used cars/trucks that scare me when previous owners re-wire stuff
Click to expand...
Yeah, that's what I was thinking too. I think it would be wise to go over that thing with a fine tooth comb. Fuses are there for a reason. Last thing you want is for your ride to go up in smoke because somebody bypassed a fuse.
 
frito said:
Yeah, that's what I was thinking too. I think it would be wise to go over that thing with a fine tooth comb. Fuses are there for a reason. Last thing you want is for your ride to go up in smoke because somebody bypassed a fuse.
Click to expand...

How would I go about chasing this down? 25k miles ago a Chevrolet dealer in SC installed a crate motor and there’s still some warranty left.
 
SNES Kirby's Avalanche said:
How would I go about chasing this down? 25k miles ago a Chevrolet dealer in SC installed a crate motor and there’s still some warranty left.
Click to expand...
Hmm, I'd take it back to them and tell them what you found. If they did, shame on them. Or, if you have a good independent shop you trust, you could have them take a look at it. I'm no electrical expert so outside those two options I don't really know. Wish I could be better help.
 
Crate motor and no fuel pump Fuse?

How did they get it to run and why they get rid of fuse?
 
I can confirm that the solution posted by SNES Kirby's Avalanche can be replicated.

I've had a 2007 Avalanche LTZ since it was new and nothing on it has been re-wired. Starting about 10 years ago, every now and then it would exhibit the same symptoms as SNES's on a very random basis. Fast forward 5 years and it would regularly work fine when it was cold outdoors and exhibit the symptoms when it was warm outdoors. It would also exhibit symptoms even when cold outdoors after it had been warmed up then parked (such as commute to work). That suggested to me it was a connection issue and likely one in the engine compartment (for example, the main fuse block). Sometimes I would whack the main fuse block or loosen it and reinstall and the problem would fix itself for a while. I had the truck in and out of the dealer more times than I can count with no success. I've had diagnostic code P0650 set almost continuously for 10 years but the "check engine light" rarely has come on.

After reading this post I started pulling and testing fuses, beginning with number 49 AUX/HVAC (note, not 4:cool:. The difference is perhaps 2007 vs 2008 model year. When I pulled the fuse, I could tell there was some oxidation on the fuse terminals. I polished it up and inserted/removed it several times to clean up the mating connectors. Problem solved. All the functions that had not been working are now working.

Specifically :
Rearview mirror compass
Rearview mirror temperature
Rearview mirror auto dimming
Instrument cluster Tow/Haul indicator
Instrument cluster fog light indicator
Instrument cluster cruise control indicator
Drivers side mirror auto dimming (and I assume heat).
All of the instrument indicators that illuminate during startup but are normally off (such as service engine light, stabilitrack off, TPMS, etc.

As for why only half the functions are impacted, that's anybody's guess. I can see now on the shop manual wiring diagrams that both fuse 46 and (on the 2007 model year), fuse 49 go to the "Junction Block Left I/P". Why GM decided to power some of these functions from fuse 46 and others from fuse 49 is a mystery. I'm just thankful for stumbling across this post and finally solving the problem after a decade of frustration and lots of trips to the dealership.

Thank you SNES Kirby's Avalanche for posting the solution !
 
KS Skibum said:
I can confirm that the solution posted by SNES Kirby's Avalanche can be replicated.

I've had a 2007 Avalanche LTZ since it was new and nothing on it has been re-wired. Starting about 10 years ago, every now and then it would exhibit the same symptoms as SNES's on a very random basis. Fast forward 5 years and it would regularly work fine when it was cold outdoors and exhibit the symptoms when it was warm outdoors. It would also exhibit symptoms even when cold outdoors after it had been warmed up then parked (such as commute to work). That suggested to me it was a connection issue and likely one in the engine compartment (for example, the main fuse block). Sometimes I would whack the main fuse block or loosen it and reinstall and the problem would fix itself for a while. I had the truck in and out of the dealer more times than I can count with no success. I've had diagnostic code P0650 set almost continuously for 10 years but the "check engine light" rarely has come on.

After reading this post I started pulling and testing fuses, beginning with number 49 AUX/HVAC (note, not 4:cool:. The difference is perhaps 2007 vs 2008 model year. When I pulled the fuse, I could tell there was some oxidation on the fuse terminals. I polished it up and inserted/removed it several times to clean up the mating connectors. Problem solved. All the functions that had not been working are now working.

Specifically :
Rearview mirror compass
Rearview mirror temperature
Rearview mirror auto dimming
Instrument cluster Tow/Haul indicator
Instrument cluster fog light indicator
Instrument cluster cruise control indicator
Drivers side mirror auto dimming (and I assume heat).
All of the instrument indicators that illuminate during startup but are normally off (such as service engine light, stabilitrack off, TPMS, etc.

As for why only half the functions are impacted, that's anybody's guess. I can see now on the shop manual wiring diagrams that both fuse 46 and (on the 2007 model year), fuse 49 go to the "Junction Block Left I/P". Why GM decided to power some of these functions from fuse 46 and others from fuse 49 is a mystery. I'm just thankful for stumbling across this post and finally solving the problem after a decade of frustration and lots of trips to the dealership.

Thank you SNES Kirby's Avalanche for posting the solution !
Click to expand...
Happy it worked!
 
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