1992 Dodge Dakota Voltage drain and drop

PHILHACHEY

MEMBER
1992 DODGE DAKOTA
V8
2WD
AUTOMATIC
238,000 MILES

Hi,
I have two problems that I believe to be related:

1. When the truck is completely turned off and the key is removed, there is a slow power drain coming from the auto shutdown circuit.(I have already tested the auto shutdown relay and found it to be OK.)

2. When the truck is running, there is a voltage drop when I turn on any electrical accessory. IE(Lights, heater, signals, etc.)

I have already replaced some parts(Computer, alternator) with no effect.

Any thoughts would be greatly appreciated.

3 Replies

MHPAUTOS

MECHANIC
31,937 POSTS

HI there,

Thank you for the donation.

You can do a current draw test that will help locate excessive current draw in any circuit, to do this place an Amp meter between Battery pos & the battery cable, do not try and start car. With doors closed and key out check current draw, if above around.2 Amps, start pulling fuses one at a time and if you pull a fuse or fusible link and the current draw drops you have located the problem circuit, try this next.

Mark (mhpautos)

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Wednesday, December 9th, 2009 AT 5:04 PM

PHILHACHEY

MEMBER
1 POST

Thanks for your response but as I allready stated:

"1. When the truck is completely turned off and the key is removed, there is a slow power drain coming from the auto shutdown circuit.(I have already tested the auto shutdown relay and found it to be OK.)"

The drain is very obvious when I remove the negative cable there is a small but visible arc. When I pull the fuse for the auto shutdown relay there is no more arc. Also the battery dosen't drain anymore.

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Wednesday, December 9th, 2009 AT 6:53 PM

MHPAUTOS

MECHANIC
31,937 POSTS

Hi there,

Have you tried to power up the 40A fuse (from the ignition switch) directly from the battery, that is isolate the ignition switch out of the circuit and see if you still get the draw down? And have you tried a new relay? My first thought was a problem with a back feed through a faulty diode but as you have said, you have replaced the alternator.

Mark (mhpautos)

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Wednesday, December 9th, 2009 AT 7:06 PM