Battery drain issue

[MTL_Dmax]

Winter always seems to highlight any battery issues and I'm seeing some drain on my batteries as well.

Now I haven't tested my alternator diodes but with both negative battery cables off and using my DMM on 10A I still get around 0.8A draw and I have been able to account for where it all came from by pulling fuses (underhood fuse panel) and testing the current draw (with the truck off) at each junction.

Here's what I found:

TBC BATT = 0.06A
CIG LTR = 0.21A
Radio = 0.02A
PCMB = 0.01A
IPC/DIC = 0.56A
HVAC/ECAS = 0.05A

So my question is are these readings normal for an LLY (esp red ones)?

If someone could verify on theirs and post what they found, I would certainly appreciate it.

[ieetgluu]

Wondering the same myself. Just made a thread today about my findings, but my primary draw is the radio @ ~1.6A. the others that had draw in the underhood box were Info @ ~.12A, TREC@ ~.06A, HVAC/ECAS@ ~.04A, and IPC/DIC@ ~.2A
The radio circuit is my main culprit, after all 5 of those fuses were pulled, I was still left w/ .18A of unknown draw

[MTL_Dmax]

Originally Posted by ieetgluu

Wondering the same myself. Just made a thread today about my findings.

radio @ ~1.6A
Info @ ~.12A,
TREC@ ~.06A
HVAC/ECAS@ ~.04A
IPC/DIC@ ~.2A

The radio circuit is my main culprit, after all 5 of those fuses were pulled, I was still left w/ .18A of unknown draw

Definitely looks like the radio is by far the worst of it.......check components to see which one is the culprit (ie radio, amps, etc). Sometimes it can just be a component that doesn't want to go into sleep mode and in which case you can just install a relay inline to have it only get power when the key is on.

[ieetgluu]

Ok, thanks, good idea. I had read in a different similar post where someone suggested wiring the Bose power to ignition. Im assuming of its 2 power wires, it should be the ignition wire and not the constant. Which is odd becasue the 'ignition' wire should already be key-on only. Or does it normally get power from the bcm so that it stays on until the door is opened(after key off)? I did notice what sound like a faint 'pop' noise from a speaker when I was getting ready to test yesterday. The drivers door was still open, I was trying to figure the door trigger so I could leave it open and test inside fuses, and I noticed a faint pop every so often. Perhaps its the Bose amp that isnt shutting down. The head unit itself seems to function properly.

[ieetgluu]

So I just looked at jc1843's post on radio wire colors and he lists constant as orange, and ignition switched as class 2 serial data, which tells me that yes the bcm, or similar module is controling the radios power. Perhaps the PO of the truck was correct in saying he heard that it might need a re-flash to correct the issue. If i rewire the constant, Ill lose the clock everyday, dont really want to go that route, atleast not yet.

[MTL_Dmax]

Originally Posted by ieetgluu

So I just looked at jc1843's post on radio wire colors and he lists constant as orange, and ignition switched as class 2 serial data, which tells me that yes the bcm, or similar module is controling the radios power. Perhaps the PO of the truck was correct in saying he heard that it might need a re-flash to correct the issue. If i rewire the constant, Ill lose the clock everyday, dont really want to go that route, atleast not yet.

Doesn't your head unit have a memory wire?

That needs to go to constant power and the rest can be on a relay (using the key on circuit to activate it).

[jc1843]

When checking battery drain-- if you disconnect the batteries and check--you will show drain --until the computers have recharged.

The way around this-- disconnect one battery cable-- I use the ground side. Connect a ammeter on the negative post, and the other on the cable make sure the connections are good] . Now disconnect the ground from the other battery. The computers have stayed charged-- and it will show battery drain.

[ieetgluu]

Originally Posted by jc1843

When checking battery drain-- if you disconnect the batteries and check--you will show drain --until the computers have recharged.

The way around this-- disconnect one battery cable-- I use the ground side. Connect a ammeter on the negative post, and the other on the cable make sure the connections are good] . Now disconnect the ground from the other battery. The computers have stayed charged-- and it will show battery drain.

Yes, I had read this proper method AFTER doing my tests yesterday. I had of course disconnected the secondary, then pulled the negative on the primary and started testing through it. Could it be that this roughly 2 amps of draw that many people seem to find on the radio circuit is the result of the 'charging' sequence as a result of improper testing procedure(ie improperly unhooking batteries)?

[ieetgluu]

Originally Posted by MTL_Dmax

Doesn't your head unit have a memory wire?

That needs to go to constant power and the rest can be on a relay (using the key on circuit to activate it).

I do believe the 12V constant IS the memory wire. Thats why its constantly supplying 12V

[MTL_Dmax]

Originally Posted by ieetgluu

I do believe the 12V constant IS the memory wire. Thats why its constantly supplying 12V

No I meant that your head unit should have both a switched power wire (main power) and a memory wire (clock, stations, etc).

Also no, I seriously doubt the ECMs would ever draw 2A......all you are doing is charging capacitors, not batteries.