2005 Suburban 1500 LT - Electrical Mystery?

[Gator Aggie]

We are at our wit's end trying to get our 2005 Suburban starting consistently again.

• Have replaced the alternator and battery but it is more complicated than that.
• Also, cleaned the PCM. There really wasn't much corrosion present. That seemed to get the burb starting correctly for about 1 day.
• Tested the following grounds that seem solid: negative battery to under driver side radiator, ground to hood, ground to back of engine (large braided ground wire). Are there other ones?
• Replaced fan assembly and related relays. That was definitely a misdirection and poor $ spend!!

I don't know if I have a hard to locate parasitic power drain or possible just a bad PCM. That sort of feels like the problem but would like to validate it before replacing. Maybe a squirrrel got under the fuse box and gnawed on some of the wires....hope not

I am new to the forum although I have owned different 3 Suburbans since 2004. Kind of speaks to their reliability since I am just now on the forum for help. Also, my son is a young car mechanic now so we have fun tackling these things DIY.

 

[Hobert]

I read here someone having similar issues and it ended up being corrosion under the engine compartment fuse box. Haven't been able to locate the post yet.

 

[strutaeng]

You need to perform a parasitic batter drain to find the issue. There's a few common sources and likely the issue, but you need to find the source otherwise you'd be replacing otherwise good parts.

 

[mattbta]

is the battery low? or is a drain speculation?

i have to ask: replaced the camshaft position sensor recently?

 

[Gator Aggie]

The Suburban will jump start easily and then the battery and alternator will read normal. Then a few hours later - the battery is drained like down to 3.50 volts or so and not even dome lights will come on. This is a brand new battery. Another weird thing it did was overheat a couple of days ago after starting it and idling. Blew smoke and coolant out of back of engine near heater core so I probably have a hose and/or connector there to replace. It was idling rough.

Have not replaced camshaft position sensor.

 

[mattbta]

ok, then my theory is not valid and you do have a massive drain.

and sounds like your coolant tees are toast, too.

 

[Gator Aggie]

We are going to look under that fuse box this evening. If the squirrels got in there, my neighborhood is about to be minus some squirrels and I can also cook some squirrel and dumplings

 

[S33k3r]

If your Suburban will Jump from a dead battery, drive for a few hours, then dies, this is likely a bad connection somewhere. As in, it works sometimes, and sometimes it doesn't. Something to check you haven't mentioned is the positive from the Alternator to the battery. They can rust and disintegrate inside the shielding. Also, the braided ground yo describe can fail in ways you might not notice with a visual inspection.

Finally, do you have a setup where you have radio controls available to the 2nd row passenger? This video might help if that is the case:

 

[Gator Aggie]

The final fix for this problem was a new PCM/computer for the Suburban. All weird electrical problems are solved now and truck is running good again. The only thing is it won't complete the crank relearn procedure. Code that is coming up is P0315, CKP System Variation not learned.
Will need to figure this one out to pass SMOG emission testing in California before too long.

 

[Fless]

It won't do the CASE relearn its own; has the variation relearn been attempted yet with a bidirectional scanner? If it has, are you saying that it won't complete it?

You may need to replace the crank sensor and, if you do, I'd recommend a GM OE sensor, then the relearn. If OE is not available, a quality part like Delphi.