Current draw too high, dead battery

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Jan 11, 2006 | 01:40 PM

Keith1984

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Current draw too high, dead battery

Went to start my 98 F-150 the other day and the starter made a thump then there was just a rapid clicking from the engine bay. Voltage of the battery was 12.06 volts. I put a multimeter inline with the negative terminal and removed the hood light. I got around 330mA which seemed excessively high? Pulled out fuse 14 for the battery saver relay/interior light relay and it dropped to 48.9mA. The interior lights shut off as they should though. Any ideas where to go next with this? Thanks.

Jan 11, 2006 | 04:11 PM

Franklin2

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From: Virginia

Look in the fuse box under the dash, and you should have a battery saver relay, and a interior light relay and a accessory delay relay. Put the fuse in, and then pull the interior light relay. If the amp draw goes down, then you have a problem with that circuit. It feeds:

right door courtesy lamp
left door courtesy lamp
left cargo lamp
right cargo lamp
interior lamp

If the amp draw does not go down, then try pulling the accessory delay relay. It feeds the power windows.

If the amp draw still does not go down, then it is something the battery saver relay is feeding directly. That would be:

engine compartment lamp
glove box lamp
map lights

In addition to the lamps above, the battery saver relay feeds the interior lamps relay and the accessory delay relay. So If you pull the battery saver relay, you will kill everything, so thats why I figured you could pull the other relays first to try to break it down to what circuit is pulling the battery down.

Jan 11, 2006 | 04:37 PM

Keith1984

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Thanks for the info Franklin. I was able to jumpstart it a little while ago, the battery was reading 14.42 VDC while running and dropped to a little over 13VDC when I shut the truck off so I assume the alternator isn't entirely dead. I put that fuse back in and it continued to read a draw of over 300mA so I've removed it for the night to see if it starts in the morning and check the voltage. I checked all the interior lights mentioned along with the hood light and all seem to turn on and off properly. I didn't try the power windows but I have a feeling that could be culprit. I'll post what I find tomorrow. Thanks.

Jan 12, 2006 | 02:02 PM

Keith1984

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Pulled interior light relay, no change. Accessory delay relay dropped it to a 176mA draw. Battery saver relay removed dropped to 48.9mA. What direction should I head from here? Thanks.

Jan 12, 2006 | 07:34 PM

Franklin2

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From: Virginia

To tell you the truth, I do not know. The new trucks are so complicated. There is a GEM module in the middle of all this too. And it all interacts together. If you could find some plugs to the power windows, you could unplug them and see what happens. If they do not have any effect, then it may be something to do with the GEM module, but it's getting very confusing to try to troubleshoot.

Jan 12, 2006 | 08:22 PM

Keith1984

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Quote:

Originally Posted by Franklin2

Thanks for responding again. During all this poking around I noticed the battery was the original so I upgraded to an Interstate MT-65. I was talking to another person about it who has service manuals for the truck and he said the battery saver provides power for 40 minutes after the key being turned to off after the run position or the door being opened. He advised leaving the meter inline for that period of time to see if drops back down to 48.9mA. I'll post my findings tomorrow.

Jan 13, 2006 | 01:35 PM

Keith1984

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Well, I hooked the meter up and waited. After 10 minutes the current draw dropped to ~160mA (accessory delay relay cutting out). 30 minutes later it dropped down to 48.9mA (battery saver realy cut out). I guess my battery was just too old and decrepit to hold a charge and what appaeard to be a leak was normal. Thanks for the help.