Troubleshooting parasitic drain after battery is connected.

[DolphineasMcGee]

So I've been troubleshooting a parasitic drain. If the truck sits for too long the battery drains. The instrument panel cluster was already replaced by the previous owner. I am in the process of doing the troubleshooting flow in this video.

When I measure inline with the battery, the current starts at 1.5A and then after about 3 seconds goes up to 2.5A. This happens every time. What could be turning on after a few seconds that is draining 1A of current?

I already tested the current draw at every fuse and the total draw adds up to ~1.5A, so there is another 1A that appears to be draining independent of the fuses. Any ideas what it could be? I know 1.5A is already too high for current consumption with nothing powered on and will go through the

I'm currently trying to clean the BCM grounds and checking the INFO fuse as mentioned here and here

 

[Fless]

What year? Are you letting the truck go to sleep after you connect the ammeter?

Do you have the AUTO HVAC head, or the manual one with sliders?

 

[DolphineasMcGee]

So I've been troubleshooting a parasitic drain. If the truck sits for too long the battery drains. The instrument panel cluster was already replaced by the previous owner. I am in the process of doing the troubleshooting flow in this video.

When I measure inline with the battery, the current starts at 1.5A and then after about 3 seconds goes up to 2.5A. This happens every time. What could be turning on after a few seconds that is draining 1A of current?

I already tested the current draw at every fuse and the total draw adds up to ~1.5A, so there is another 1A that appears to be draining independent of the fuses. Any ideas what it could be? I know 1.5A is already too high for current consumption with nothing powered on and will go through the

I'm currently trying to clean the BCM grounds and checking the INFO fuse as mentioned here and here

UPDATE: After removing the INFO fuse, current draw is ~0.02A. When I reinsert it, it goes up to ~1.25A.

 

[DolphineasMcGee]

What year? Are you letting the truck go to sleep after you connect the ammeter?

Do you have the AUTO HVAC head, or the manual one with sliders?

I actually just realized I wasn't giving it enough time to shut down. Current draw would go from 1.5A to 2.5A and then back down to 1.5A. The connectors going to the ECU were super rusty. One of the bolt threads partially stripped when I was removing it so I have another problem now, but should be easy to fix with a self tapping bolt or bolt-nut combo.

Auto HVAC. It also turns on every time I reconnect the battery.

 

[Fless]

I actually just realized I wasn't giving it enough time to shut down. Current draw would go from 1.5A to 2.5A and then back down to 1.5A. The connectors going to the ECU were super rusty. One of the bolt threads partially stripped when I was removing it so I have another problem now, but should be easy to fix with a self tapping bolt or bolt-nut combo.

Auto HVAC. It also turns on every time I reconnect the battery.

Normally most of it will go to sleep within a couple of minutes. But the AUTO HVAC control can take as long as 4 hours to fully sleep. Until it fully shuts down it can draw 60 or 70 mA (0.060-0.070 amps).

You want to be careful pulling fuses. A module you shut off that way may have a "relationship" with another module and may not be the source of the problem. It's best to leave everything in-circuit and measure the voltage drop across the fuse, then use the conversion chart that Power Probe puts out. Yell if you need the link to it.

 

[markman57]

I just replaced my completely dead instrument cluster with a reconditioned one , hoping it will cure my battery drain. perhaps previous owner used another bad cluster?