o4 grandmarquis ls battery drain


Asked by Apr 19, 2015 at 02:48 PM about the 2004 Mercury Grand Marquis LS Premium

Question type: Maintenance & Repair

I have an o4 grand marquis ls and my battery keeps draining, I did a parasitic draw test and found out my battery is draing very fast however I pulled every fuse and found no fuse that would stop the drawing of power from battery. I also checked the ground and everything is good.  Any suggestions would be appreciated. Thanks

9 Answers


Is there anything installed that doesn't go through the fuse box?

2 out of 2 people think this is helpful.

do you mean anything aftermarket? if so no. Everything is stock

1 out of 1 people think this is helpful.

How old is the battery? Have the battery load tested. HTH. -Jim


Battery is new and holds charge but over time loses charge due to a draw somewhere

2 out of 2 people think this is helpful.

If this is a car that you don't use a lot you'll want to disconnect the negative (-) battery cable when you park it. Does it have rear air shocks? If so maybe the compressor is cycling to maintain the vehicle height. My '94 Fleetwood does that. Check to see if the blower motor for the heat/air conditioning is running. Are any lights staying on? HTH. -Jim


no air shocks, no light on or heat

1 out of 1 people think this is helpful.

The alternator is one suspect, disconnect the power wire from it (the heavy one) and re-check. This is my specialty. If you hook up a 12v light bulb between the batt. pos and the car does it light up? If not, use a seat belt buzzer or such. It will buzz and drive you crazy, but then disconnect wiring harnesses and devices until it stops. I bet it's the alternator, I ran a cross a ford doing this. Disconnect all wires to it when testing. Bad diodes, or regulator inside.

2 out of 2 people think this is helpful.

thanks will try and get back


I used a volt meter on battery ground and put the positive side on the wire harness part of alternator. I was reading 3.76 volts when car was in the off position. So, it must be the alternator trippmeister because their should be no draw from alternator when car is off. Thanks .

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