2013 Chevy Express 3500 ext Pass Parasitic draw

[Justinwells14]

I have a 2013 express. The bcm-1 fuse under hood has an draw of .200-.440 Milamps. The draw is some what intermittent, some times it will drop to .040 Milamps, and stay that way for no repeatable amount of time, jump to .200-.400 and may stay that way until battery dies. I have checked all circuits under driver seat in fuse block and could not narrow it down. The BCM has been replaced and reprogrammed.

Wiring diagram shows BCM-1 FEEDS 2840 RD/WH ({LU3/LMF} NOT SURE WHAT THIS IS) & 3840 RD/WH.

Any help resolving this issue would be greatly appreciated.

[carriedi]

this is going to be a tough one. a draw is bad enough but an intermittent draw is the worst. If you found the fuse with the draw you want to trace (BCM1) you now have to find out what leg of the circuit you need to look at. So, you will have to monitor the wires on 10 on x4 and pin 3 on x3. Once you find out which of those two circuits has the draw then you have to see what outputs from that circuit could be causing the excessive draw. It shouldn't be internal with the BCM since you have change it out but you never know...

Once you figure out if it's the x3 or the x4 circuit let me know the I can go from there

btw: do you have any aftermarket equipment added to your vehicle?

[Justinwells14]

It has a flip down tv (has been disconnected) has inverter with rear battery with dc-dc charger (also disconnected). Has aftermarket radio,Connected.

[carriedi]

by your first diagram, when the draw is present, have you pulled the relays that is shows to see if one of the two relays is being stuck on? (the retained accessory power relay or the ignition run relay) Actually before you pull the relays, When the draw is present, tap on the relays and see if they click to open. If you hear or feel a relay click when you tap on it then that relay was stuck on and when it clicks open then the draw will be gone. Bad relay. Get a new one. If the draw doesn't go away after tapping on the relays, then remove the relays one by one and see if the draw goes away. It is not all that uncommon for relays to get stuck in the on position. Every time the relay turns on there is an electrical spark and there can be some metal transfer just like arc welding (in a micro way) Sometimes the spark will be just right that it will make the contacts stick together.

try the relays and see if that makes any difference.

did the radio use a factory harness connector to attach the vehicle harness or are the wires cut and spliced in?

[Justinwells14]

Yes the radio was plug and play, I have checked the relays and changed them out with other relays all 4 of them under driver seat no change.

[carriedi]

your wiring diagrams are hard to read but it appears that the fuse to the BCM that has the draw only goes to two relays. Is there more outputs not listed on the diagrams?

did you disconnect the relays while the draw was on? Did the draw change when you pulled the relays?(RAP relay and run relay) Because it's an intermittent draw you can only verify by changine while the draw is on. What down the circuits turns the draw off