battery discharges after the truck is shut down

[garywayne]

1986.5 Hardbody,vg30i, new napa alternator and starter and battery,at least once a week the battery will be almost dead. The alternator does charge when I start it up as long as I rev it up once to excite it.I have checked the cables and grounds good.Also I did replace the starter relay, it seems like there is something that intermittently drains the battery after the truck sets for a day or so. I would appreciate any help as this has been going on a long time.

[seang]

Its almost like there is something draining the battery.

How is the battery itself? Are the terminals clean?

[garywayne]

Good battery! Good cables and clean too! I am baffled! Thanks for the reply!

[garywayne]

Could a component in the alternator cause the battery to drain after the key was shut off?

[Rev_D21]

Remove the negative battery cable. Put a test light between the cable and the negative post on the battery. Do not start the truck! Start pulling fuses one at a time until the test light goes out. Once the light goes out you will know which circuit is drawing from the battery when the truck is off.

[RT22]

Rev is right you have a drain and his way is the fastest way to isolate the circuit by pulling the fuses one at a time. Once you get it to the fuse look and see if any aftermarket stuff has been put on that circuit. If not then you may have to start unpluging what ever is on that circuit until again it quits drawing amps. Good luck and if you can get a electrical schematic it would make it easier. Not sure of haynes or chilton manuals from parts stores have them.

[garywayne]

Thanks for both of your replies .I will try your method. It seems to be an intermittent problem so I hope it is acting up when I am testing it. Is there a voltage regulator that is separate from the alternator on this truck? I can not see one.

[pejsa s-13]

my friend has a similar problem on his truck then we realized when his truck was shut off his fuel pump continued to run we just couldn't really hear it

maybe something you want to check

[s13_240_rb20]

For the longest time, I failed to realize that during my engine swap I wired up my ECU's "IGN" wire straight to the battery with the other ECU power wires. This kept my ecu on full time.

But my real question is did you check your new alternator's IGN signal and sense signal wires for voltage when the key is off???

--TJ

[RT22]

my old mazda had bad light switch and in the middle of the night the parking lights popped on and drained my battery a few times. I just happen to see em on one night, I yanked the fuse at night until i found switch in a junkyard, as stock was crazy high.

[garywayne]

Wow you guys are full of great ideas!No. But Iwill!