Identifying current draw in circuit

Thread Starter


Joined Jul 1, 2009
Short story:
I have a pcb with a 300mA current draw where there should be none and Im trying to figure out how to identify the offending component or location.

Long story:
So I have a 2005 Chevy Silverado with a current draw coming from the instrament guage cluster. The plug into the guages has 2 grounds and 3 hots. On the hots, 2 are only hot with ignition on, with 1 being hot at all times.

The hot at all times when connected pulls 450mA for 25 seconds and then drops to a constant 300mA. From what I have read, total acceptable draw for the whole vehicle should be 30-50mA. I borrowed an identical one to test, and it pulls the same for 25 seconds, but then drops to under 1mA.

I reflowed all the components hoping that maybe it was a cracked solder joint somewhere, but no luck.

What process would I use to track down the source of the draw on the board?

Thanks for any help.
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