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2006 F150 key off battery drain

canblue

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I have isolated my key off battery drain to the rear wiring. If I disconnect the major connection bus near the parking brake pedal ( the one that has the bolt in it) the draw stops. The draw is about 3 amps. It is winter here in Ontario Canada - no snow yet but it is getting cold. Since I do not have a warm place to work, any major detective work will have to wait until the warm weather. Right now I disconnect the battery after each outing if the truck will be sitting for a few days. What could be the possible source of the draw. Looking for some suggestions to start the investigation when the sun shines.
 
When you say rear wiring do you mean the wiring to the rear lights? Does it have a trailer connector?
 
As far as I can tell it is all of the electrical stuff rear of the crew cab. Rear lights etc and yes it has a
factory trailer tow package. On the 2006 F150 the connector is C238. There are 66 pinouts in the
connector. Less than 12 positions are not used. I'm trying to develop a plan for when the warm weather gets here so that I can get back on the problem.
 
I have a few wiring diagrams but none of the diagrams go beyond circuit number and wire color. I was hoping to find a diagram that would have some indication as to function ie right tail light. I spent
a few hours trying to map the obvious circuits but it get confusing when they change color at the connectors.
 
I did check each pin in the connector, well I thought I did. I must have missed one or two or more as I did not find a large amp draw. Even if I found it, there will be a long process of tracing the circuit and wire color through many connectors. Working from the front to the back is not working for me. That is why I am hoping for a short list of most probable sources of draw and work from the back forward.
 
Is the C238 connector the one near the parking brake pedal that your disconnecting? I have access to wiring diagrams at work so I can ck out the circuits you want.
 
Thanks 65 sporty.

Yes, C238 is by the parking brake. It is the connector that has a bolt. Thank you for the offer to check out the circuits. I have a few Ford wiring diagrams. They are good but are terribly short on information, from my view. If you have more information on the circuits -- more than circuit number and wire color, please do a little checking. If there is a list of circuits and functions I would like to see it. As I indicated previously, there at 66 pins in this connector with a few not used in the list. I have spent months searching for information on the circuit numbers. If you or your friends have any thoughts as to what are good candidates, let me know. Any and all information appreciated.
 
I will look and see if I can find a list of each pin for C238, I will let you know.
 
I think I have fixed the battery drain problem. When I checked the "battery draw" yesterday it was around 500 ma. What I found, when I was replacing the Diff oil was a broken and corroded part on a crossmember under the bed. I had removed the spare tire to find an air leak in the airlift system. It turned out that the part I saw was the fuel pump control module. I replaced that part. Who designed that piece? Who authorized that an aluminium part would be bolted to a steel member? I will be testing it again soon. If it was not for the air leak-- who knows what would have happened when.
Thanks for all of the input and suggestions.
 
I think I have fixed the battery drain problem. When I checked the "battery draw" yesterday it was around 500 ma. What I found, when I was replacing the Diff oil was a broken and corroded part on a crossmember under the bed. I had removed the spare tire to find an air leak in the airlift system. It turned out that the part I saw was the fuel pump control module. I replaced that part. Who designed that piece? Who authorized that an aluminium part would be bolted to a steel member? I will be testing it again soon. If it was not for the air leak-- who knows what would have happened when.
Thanks for all of the input and suggestions.
Bolting aluminum to steel? Maybe a neutralizing grease was applied with a stainless fastner.
 
Bolting aluminum to steel? Maybe a neutralizing grease was applied with a stainless fastner.
What he is talking about is the fuel pump driver module, it is bolted to a frame crossmember in front of the spare tire. The module is aluminum and sits right on top of the steel crossmember, it will corrode right through the module. All the replacement modules come with different bolts to space them off the crossmember. Big problem here in the rust belt, I have changed quite a few of them
 
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