Can a bad ecm cause this?

[IowaCummins]

Alright I have been having a battery drain issue for a few weeks and its only if the truck sits for 2 or more days, tonight it was dead. Charged it and started it, let run for ten min then went to drive. Lights were dim and only said like 8-9 volts on the gauge. Figured the charge cable came un done on the alt, nope good connection. Unplugged or plugged the lights have no effect, so alt is not doin its job. Its brand new from napa 8 months ago.
also my wait to start lights will not come on"also grids" at times but will kick on after it is running.
So could all these be symptoms of a shorting out or bad?

[IowaCummins]

any one?

[ellis93]

I start checkin fuse links and fuses before anthing.

[Mark Nixon]

Defintely check fusible links, general connections and grounds.
Another thing you can do for an on-vehicle alternator test is get a spiked wire probe and clamp it to the GREEN wire at the alternator harness and momentarily ground it, (a few minutes shouldn't hurt anything) and if the alternator charges, it's likely in the PCM.

If it DOESN'T charge, next spike the BLUE wire and go directly to the positive on the battery.
If it charges then, it's likely in the main wiring harness somewhere.

You can also do BOTH, effectively isolating the alternator from the harness, to be 100% sure it's not wiring somewhere along the line.

While I have you here, did you still want to finish the deal on those tubes and intake pieces?

Mark.

[IowaCummins]

Thanks Mark I will try this tomorrow. I checked all fuseable links all are good. Cleaned connections on alot of stuff, found that my KSB has a continuity woth ground but assume its just.due to the coil.

The tubes, yes Mark were still good with those either once my truck is running I can drop em off or if your comming near omaha any time just give me call and we can meet up.
Thanks again