# The curious case of the flat tire that led to a drained battery



## Brainbucket (Mar 30, 2015)

12 volt test light between negative cable and batt neg post. Momentary touch cable to post. Test light may flash. That is computers waiting to go to sleep. Wait a few minutes for the computers to go to sleep. Light should get dimmer then out. If it doesn't, start pulling fuses and reinstall the fuse if test light doesn't get dimmer or brighter but stays the same. If test light varies, record that fuse and continue pulling fuses. If test light goes out. Bingo. Now you have to find out what is on that circuit. Reinstall fuse and test light should come back on. Start disconnecting items that are on that circuit untill light goes out. You have just found the draw. Door latches must be closed. Hood up is ok. Sometimes I have to do that 2 or 3 times until I get what the test light is doing.:vs_cool:


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## de-nagorg (Feb 23, 2014)

That clock in the system will pull some, as well as the ambient temperature and GPS, and lots of the other electronics, 

Does this have a light that comes on when the hood is raised? (some do), if so the switch might be stuck on full time, and will drain the battery, as well as cargo lights, and even a light in the glove box.


ED


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## GrayHair (Apr 9, 2015)

Another possible 'vampire drain' is a light on a sun visor.

Many years ago, but I once had the same problem and finally traced to the ignition switch (dash mounted). Rare, but don't discount the possibility.


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## de-nagorg (Feb 23, 2014)

Gray: You reminded me of an incident that I had Sooooo many years ago.

This customer brought their vehicle in complaining about a constantly draining battery. 

Did all the tests , everything was charging great, no drains, nothing to find.

Until I realized that the vehicle had been in a minor fender-bender, and the chassis ground had been compromised. 

This allowed the VAT-40 tester to show a great charge, but it was not getting to the battery, but the vehicle was still running and draining the battery.

Rigged a new chassis ground, and they were going again. 


I do hope that their Navigator has not been banged up, and doing something similar.


ED


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## Brainbucket (Mar 30, 2015)

Over the years I have found a lot of draws and shorts. But a passenger sun visor light was one that made me laugh and it took a while to fine it.:glasses:


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## Bigplanz (Apr 10, 2009)

One interesting side effect of having the battery disconnected was that the fuel trim levels of the computer have reset. Now the thing idles fine. Hasn't died since.

On the other hand, now that the weather has turned colder, the tailgate won't stay up.


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## de-nagorg (Feb 23, 2014)

Every liftgate that I have ever had, the struts wore out too soon for my wants.

But they are easy to change, and work soo much better afterwards that I am very pleased.

I have changed many, you also have them now to hold the hood up.

I suggest that you get a complete set for your Navigator, HOOD, LIFT GATE, AND liftgate WINDOW.

They are cheaper as a set and you are going to need all of them sooner than later.


ED 

PS: glad to hear that a reset of codes settled your idle problem.


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## Bigplanz (Apr 10, 2009)

There I was, in the parking garage, shredded tire, car alarm blaring, trying to fish a 7mm socket out my toolbox and the tailgate bangs me on the back of the head. People yelling to shut the alarm off, honking and pointing. Yeah, it was stressful. Raining, pouring and all that. 

Struts are an easy fix though. Two clips hold them on, pop, pop, they're replaced.


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## carmusic (Oct 11, 2011)

pretty normal if battery is not top notch to be drained with 1 hour hazard light flashing, my car when it had original battery was drained within 30 minutes with hazards lights, with new battery it takes hours


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