Severe battery drain!

[MountaineerGreen]

I haven't been driving the Mounty much lately, but everytime I go to start it, the battery is dead, even after a few days. So today I started searching for the cause. The battery is in good shape, holds it's charge well when disconnected from the truck.

I have a "digital" battery charger that shows the battery in percentage. Disconnected, the battery dropped 5% in an 8 hour period- I intend to load test it tomorrow.

I put a multi meter between the negative terminal and the connector on the Mountaineer with the key off, all additions I made removed from the system, there is/was a 9V drain continuously. I pulled each fuse one by one, watching the needle, it never moved, I even pulled the fuses under the hood, no change. I disconnected the alternator and the 3 wire connector on it just for kicks. The drain is still present.

I contemplated replacing both the positive and negative battery cable, but its going to be an extensive job, it routes under the motor, joins a loom that also contains other wires. It's going to be a royal pain.

What else can I do or check??

 

[section525]

Also the positive terminal is $300+ from Ford.

 

[MountaineerGreen]

Eh, I've modified or am going to modify everything else, whats a battery cable? There is a place that can make custom cables round here.

I have constant corrosion problem on my negative terminal- could that be related?

 

[Tbars4]

...Yes it could....It could also be the reason for your battery not being able to hold a charge even while it's disconnected...

...I suggest both cables and a new battery...Hopefully the alt didn't start going south..

 

[MountaineerGreen]

Well that brings up a good point- my alternator and battery were both replaced last summer when I was still driving it full time. It's a quality alternator, a 75 month battery- I have a friend in the battery business, if mine is even borderline bad, it will be replaced.

 

[Turdle]

hmm
A corroded cable maybe, but I wonder what would happen if you disconnect the starter wires then take a reading-

 

[Tbars4]

...A bad or corroded ground cable will take a battery, alt, and possibly a pcm out in a hurry...If it's corroded enough inside the jacket you will have a "short" situation even if you can't detect it right away...

 

[bt93]

Could you just add another ground cable, say from batt to block, and see if it corrects the problem temporarily? If it does you'll know where to start.

 

[MountaineerGreen]

*I think* just adding another ground wouldn't get rid of the draw unless I found both ends of the cable and disconnected it, and I'm pretty sure the starter will have to come off to get the end of the negative cable off.

 

[bt93]

*I think* just adding another ground wouldn't get rid of the draw unless I found both ends of the cable and disconnected it, and I'm pretty sure the starter will have to come off to get the end of the negative cable off.

Thats what i was talking about. We could remove both ends, replace it with a test cable and charge the batt. Then see how long it takes to drain the batt.

 

[Cobraguy]

Also the positive terminal is $300+ from Ford.

I don't think that's correct Section. It's just under $100 at Rock Auto. Motorcraft WC9451E for a 2001 Mountaineer. I just replaced mine. It's worth every penny. There's a lot more than a starter cable to it. It's an entire harness to the starter, megafuse, and the message center connector. It has all the hangers, etc to properly mount it. Once I had it in my hand, I could see why it's so spendy.

Mountaingreen...I assume the battery case itself is clean. If I can find the clip, I can show you where a dirty case actually conducts electricity and draws the battery down. It's amazing.

I've also seen where everything is disconnected, but the battery still drains down. It's a defective battery.

If any of the connections are poor, you won't get a good charge. I would do a voltage drop test across your connections. Best test there is for this kind of thing.

One last thing. I have seen a lot of vehicles with 7 to 9 volt draws that were considered normal these days. I'm not so certain you have a problem with your draw. However, on a 2001, that does seem like a lot. Check for amp draw and see what you get. Another simple test is to hook a test light between the negative post and cable and see if it lights. If it does, it's too much of a draw in most cases. If not, I doubt you have a problem and need to look at the charging system, battery, or connections.

Oh yea...my mom has a brand new Lincoln. She doesn't drive it much. If she lets it sit in the garage for several days without starting it, you can tell it's drained down when she goes to crank it. It just doesn't have the reserve in the battery and doesn't spin the motor like it should. If she starts it every two to three days, it fires right off.These things to drain a lot of power just sitting these days.

 

[Turdle]

The Pats is constantly sending voltage thru the wire harness, looking for a drop.

are you setting the pats every night? I wonder what would happen if you didn't set it-

 

[Cobraguy]

Jt...How can you set PATS? It's always looking for the correct key transponder. I didn't know of a way to turn it on or off. Are you talking about doing it with a tune? Does that shut it off or just make it so it doesn't look for specific keys? What type of voltage drop is it looking for? That's new to me. Interesting comment...

 

[Turdle]

Doors unlocked, no alarm-
The horn sounds on the 2nd door lock command from the FOB
this is when the pats alarm system is armed-and pulsing the harness with voltage-

Since I switched to LED tail lights, I can see this slight pulsing in my 3rd brake light-at night-
when the pats is armed-it glows very dim and steady

 

[Cobraguy]

Ahh...ok. That's the perimeter alarm. I wondered if that's what you were speaking about. PATS is the system that ties the key frequency to the ignition sequence. That can only be disabled by an aftermarket tuner to the best of my knowledge.

 

[MountaineerGreen]

I don't think that's correct Section. It's just under $100 at Rock Auto. Motorcraft WC9451E for a 2001 Mountaineer. I just replaced mine. It's worth every penny. There's a lot more than a starter cable to it. It's an entire harness to the starter, megafuse, and the message center connector. It has all the hangers, etc to properly mount it. Once I had it in my hand, I could see why it's so spendy.

Mountaingreen...I assume the battery case itself is clean. If I can find the clip, I can show you where a dirty case actually conducts electricity and draws the battery down. It's amazing.

I've also seen where everything is disconnected, but the battery still drains down. It's a defective battery.

If any of the connections are poor, you won't get a good charge. I would do a voltage drop test across your connections. Best test there is for this kind of thing.

One last thing. I have seen a lot of vehicles with 7 to 9 volt draws that were considered normal these days. I'm not so certain you have a problem with your draw. However, on a 2001, that does seem like a lot. Check for amp draw and see what you get. Another simple test is to hook a test light between the negative post and cable and see if it lights. If it does, it's too much of a draw in most cases. If not, I doubt you have a problem and need to look at the charging system, battery, or connections.

Oh yea...my mom has a brand new Lincoln. She doesn't drive it much. If she lets it sit in the garage for several days without starting it, you can tell it's drained down when she goes to crank it. It just doesn't have the reserve in the battery and doesn't spin the motor like it should. If she starts it every two to three days, it fires right off.These things to drain a lot of power just sitting these days.

The battery is defective- went completely dead with a load test- one cycle. This is my second battery- the other one did this also, these are quality batteries. The alternator is charging fine, tests OK.

The battery itself is clean- I was under my hood fairly often.

What prompted you to change your cable? Did the cable you bought include the negative cable?

I had a little corrosion on my negative terminal despite ani corrosion spray and washers- I suspect the cable is corroded inside.

The Pats is constantly sending voltage thru the wire harness, looking for a drop.

are you setting the pats every night? I wonder what would happen if you didn't set it-

I don't lock the doors when I park it- I usually leave the key in the ignition when it sits.

Now that this battery is bad, I suspect that I have something causing them to go bad.

 

[section525]

Thats a great price on the harness! I looked into it a couple years ago for the Mountaineer. Ford said $278, I said no thanks.

 

[MountaineerGreen]

Cobraguy- I found the cable on RockAuto, it does include the negative cable, but it says with message center. I don't have the message center though. What's the difference?

EDIT: I also have a pimpin diagnostic multimeter on the way I'll find my short/drain soon enough.

 

[CDW6212R]

The tips in here are all very good. I have a 95 Crown Vic that has always had corrosion accumulate fast on the ground terminal. It had the cable cut off(bolt on terminal) and the corrosion even turns up on the AC lines close by. I didn't have any trouble with it unless I parked it for days or weeks.

Most old Ford parts do often replace many parts. Meaning that all versions except one will be obsolete. The Explorer power steering hose is still available, but the Mountaineer part(sensor in line) is not. Ford does odd things.

 

[99SportX]

If it says with message center, it is because the harness includes wiring for the oil level/temp sensor in the pan.

This sender is not far from the location of the starter, so they bundled it all into one harness.