2000 Grand Marquis 12v draw

[hypostang]

My friend has a 2000 GM on her used car lot that has a 12v draw that I cannot for the life of me figure out

I have disconnected everything I can think of , pulled each fuse one by one , the only way I can get the draw to stop is to remove the combination of fuses shown in the pics below

Please ...........any insight or help will be greatly appreciated

[86VickyLX]

well now here's a thought. What do each of those fuses protect? And what do they have in common? If you leave any of those fuses in, is the draw there?

[hypostang]

If I put ANY of those fuses back at all the draw comes back . It does not matter which one . I tried disconnecting the LCM , the ignition switch , the alternator , the ECM , Drivers door switches , the power seat switch , trunk light , radio , blower motor , cooling fan . anti theft module , dome light , as well as any other electrical plug I could find

I don't have the owners manual , so I am guessing what the fuses do to be honest .

[86VickyLX]

If I put ANY of those fuses back at all the draw comes back . It does not matter which one . I tried disconnecting the LCM , the ignition switch , the alternator , the ECM , Drivers door switches , the power seat switch , trunk light , radio , blower motor , cooling fan . anti theft module , dome light , as well as any other electrical plug I could find

I don't have the owners manual , so I am guessing what the fuses do to be honest .

Didn't I give you a link to mitchell?

[hypostang]

Didn't I give you a link to mitchell?

If you did I missed it somehow

[sly]

PDF download of owners manual at MotorcraftService.com

[hypostang]

Ok , I got the fuse diagrams , I went there today and after much testing and figuring , here is where I ended up .

If I disconnect the PCM (ECM) the LCM and the key-less entry module the draw stops , but all three have to be disconnected, I also found that the power door locks will NOT work from inside the car if the LCM is disconnected , but the remote key fob will work .So I know that the LCM is integrated with the keyless module somehow .... So Tomorrow I am going to my local pullapart to get an LCM and see where that goes .... I will post an update tomorrow

What I find very strange about this whole thing is that EVERYTHING works properly in the car ... It just kills the battery

[sly]

sounds like a controller chip burnt, but not broken, high current draw. Could be any of the 3 modules you quoted. I'd bet on the LCM as well though.

[hypostang]

ok , I went to the yard today . I bought 3 (THREE) LCMs ( they only cost 5.00 and they are returnable ) and one key-less module ... No change no matter what combination of LCM / Keyless I tried .
Is it possible that the PCM could be causing all of this

[sly]

I can see the ECM causing it... but I didn't think the PCM had an always hot line going to it. But if it does... then yes... it could be causing it. It can also be caused by crappy wiring and a resistive short between two wires (one strand touching).

[hypostang]

I can see the ECM causing it... but I didn't think the PCM had an always hot line going to it. But if it does... then yes... it could be causing it. It can also be caused by crappy wiring and a resistive short between two wires (one strand touching).

Ok thanks , I will return the 3 LCMs and use the credit to get a PCM (also returnable )
If that don't cure it , the car gets a price drop and an "as is " sticker .. I'm not chasing a wire harness problem for free on a car I don't own .

I really thought it was going to be something easy I could help her out with

[sly]

electrical is never something easy when it's something like this "it drains the battery out when it's turned off".

Of course... if the battery has some weak cells... that could also be why.

[hypostang]

electrical is never something easy when it's something like this "it drains the battery out when it's turned off".

Of course... if the battery has some weak cells... that could also be why.

This is definitely not the battery , I have had a test light hooked up to the negative cable and the other end on the post ... It lights up bright until I disconnect the three previously mentioned components

Update as soon as I get back to the pullapart

[miamibob]

You may wish to check the keypad for the keyless entry. I have seem them get porous and short out after it rains. After drying out all is well. Have to replace it with a new, good one as I don't think there is a way to repair it. Strange but true......

[hypostang]

You may wish to check the keypad for the keyless entry. I have seem them get porous and short out after it rains. After drying out all is well. Have to replace it with a new, good one as I don't think there is a way to repair it. Strange but true......

Actually now that you mention that , the keypad wasn't working .... but I unplugged it and still had the draw , so I (in my mind) dismissed it as the problem.

Sooooo ....the question is if that is the problem, does a functional keypad have to be installed to eliminate the problem OR should disconnecting it be enough?