Parasitic draw narrowed down to BCM ?

[Quickets2004]

2004 Tahoe LT 4.8L 2wd

Before going into the details, first thing
Other then the anti-theft relearn, Dose the BCM need to be programmed to the truck.
I going to purchase a Dorman 502-007 BCM and don't want to be surprised with needing to take it to the dealership to get it to work.

First the symptoms.
Aftermarket radio would randomly shut off and restart. (Kenwood DNX7140)
Been doing it for months.
(Radio installed with harness adapters no cut wires)
Then battery died, thought it was because it was old and the random Florida cold snap finally killed it.
Got a brand new battery, Truck sat 2 days, and needed to be jumped.
Now the radio won't come on at all but has a blinking power light
Alternator is fairly new and tested good.

After the jump start, (never noticed this before)
Once I turned everything off and removed the key, and the doors locked with the remote The battery red light would stay on and the cluster back lighting would still be on and the windows still had power.


Then I did a parasitic draw test with a clamp system multimeters around the negative cable (battery not disconnected)
Got a draw of 00.76 amps, started pulling fuses got to the IPC/IDC 10amp fuse
(Cluster) amps dropped to 00.28 amps
Then I got to the TBC BATT 10amp fuse amps dropped down to 00.16 amps.

Left both fuses out over night battery voltage remained 12.7 volts
Put cluster fuse back in amps jumped back up to 00.76 but after a minute or so
Went down to 00.16 (BCM fuse not in)
and after playing with pulling BCM fuse a few times got the Amp draw down to 00.07 amps.
I've left it over night again battery voltage still at 12.7 volts.
Put BCM fuse back in also amps jumped to 3.20amps then after a few minutes dropped to the 00.76.
I've been pulling the BCM fuse now every day when I park the truck and haven't had any battery issues.
(Radio still not coming on)
I haven't timed it but today I was sitting, no key and doors closed and locked with the remote, for at least 5 minutes and the cluster was still lit up and battery light on and windows still working, tried opening the doors and windows still worked.

Any ideas if I'm on the Right track with the BCM ?
And again dose it need to be programed to work?
Thanks for the help.

 

[Fless]

What's the make and model of your clamp meter; what's its spec/range/accuracy for measuring DC amps, or are you direct wiring it? This low of current draw will require a very small clamp.

Measuring the voltage drop across the fuses (the small ones have test points on them) is way more efficient to track down circuit draw than pulling fuses. There are many good YouTube videos on the best ways to measure parasitic draw.

The instrument clusters are known to get silver migration on the circuit boards; that's a possibility more than the BCM. The BCM is likely not at fault -- something else may be keeping it awake.

Also, does the RAP work properly? Does the radio shut off automatically after about 10 minutes after turning off the engine? After turning off the engine does the radio turn off when any door is opened? Any interior lights staying on?

 

[Quickets2004]

What's the make and model of your clamp meter; what's its spec/range/accuracy for measuring DC amps, or are you direct wiring it? This low of current draw will require a very small clamp.

Measuring the voltage drop across the fuses (the small ones have test points on them) is way more efficient to track down circuit draw than pulling fuses. There are many good YouTube videos on the best ways to measure parasitic draw.

The instrument clusters are known to get silver migration on the circuit boards; that's a possibility more than the BCM. The BCM is likely not at fault -- something else may be keeping it awake.

Also, does the RAP work properly? Does the radio shut off automatically after about 10 minutes after turning off the engine? After turning off the engine does the radio turn off when any door is opened? Any interior lights staying on

Kaiweets HT206D, I got it off Amazon $45
My knowledge of electrical is basic, power & ground and dose the test light light up lol.
I watched alot of YouTube videos, still not sure of it all.
The radio just has a flashing power/security light now
When the radio is on and working that light stays solidly lit. Radio would shut off as soon as the key was turned off.
The interior lights go out after a few seconds, they have remained working normal.
Not sure what the RAP is ?
When the truck is running there's nothing wrong with anything on the cluster and the battery light is off while it's running.

Also just remembered that randomly the A/C would switch to blowing hot air, out of the vents
Tried a number of combinations on the a/c head unit but would stay blowing hot
but turning the truck off and back on would fix it. Hasn't done it in awhile.

 

[Fless]

RAP is Retained Accessory Power. It should keep some of the accessories alive after the ignition key is removed, until any door is opened or it times out. Your Owner's Manual should detail how long it is -- usually about 10 min. Get your owner's manual free from

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I wouldn't trust a meter with that large of a jaw opening to be accurate for very low DC current measurements. If the expected current is less than the wired connections will allow (meters vary, usually 5A or 10A fused), using the wired connections would be most accurate. You could verify accuracy by making a wired vs. jaw comparison reading.

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

You are already receiving clarifying questions from the knowledgeable folks on this Forum.