Hey guys, I'm running into a strange issue with my 2006 Ranger 4.0L auto 4x4. Last year I replaced the battery since it needed replacing. Easy swap, all went well. However, about a week later I was driving the truck out of the driveway and all of a sudden I lost all electrical power. Everything shut off and went dead for a second. Then all my dash lights and gauges turned back on, I turned the key and the truck fired up no problem. A few weeks later it happened again. Instant loss of all electrical power, truck dies for a second then everything kicks back on again and starts right up. My first guess was something with the battery since I had just replaced it but I got to thinking that if the truck is already running then a bad connection at the battery terminal or bad battery wouldn't cause it to loose all power and die. I decided to clean all of the relays and fuses and make sure they're all set in their slots correctly. That seemed to fix the problem until today when it happened again. This time the truck died for about 10 seconds and I had no power. I tried to crank it over and nothing, no gauges, no radio. Then all of a sudden everything turned back on and the truck fired up. What could be causing this? Based on how intermittent and short it is I feel like I should be looking for some sort of bad connection or loose wire but I'm not exactly sure where to look or what else it could be. Any ideas? Could it actually have been the battery? Seems highly unlikely since it's only happened a handful of times.

 

Battery is only used when engine is off
After startup alternator supplies all the voltage for the vehicle
Battery is 12volts
Alternator uses 13 to 14 volts so alternator provides all the voltage and keeps 12v battery charged

But it alternator stops working the vehicle can still stay running using the battery volts

The battery's smaller red wire(positive) hooks to engine fuse box, and the Alternators red wire hooks up to the same spot on the fuse box
So if that one connection was corroded or bad then you could lose all Positive power, thats the only place in the system that could happen

There is no 12volts, or 14volts, unless there is 0volts, negative/ground, thats the way DC power works, it must FLOW from one pole to the other to work
If you hook up a 12volt light bulb to 12volts nothing happens, light bulb must also be grounded, hooked up to the 0 volts, battery negative
So check those cables as well

 

Thanks RonD and thanks for also posting on my thread over at TRS https://www.therangerstation.com/for.../#post-1816575

I was able to clean the positive and negative posts on the battery (not really that much corrosion but a little bit), where the wires connect to the positive and negative terminals, the negative ground to the body, and the two wires connecting to the fuse box. Everything looked fine but I scrubbed them anyways and applied some Super Lube Anti Corrosion Gel to all connections.

I was not able to clean the negative ground to the engine (too much snow on the ground) but I was able to get my fingers on it from above and it's tight. It seems so strange that the problem is intermittent and it's difficult to diagnose or track it down since I cant replicate it on demand. For now hopefully cleaning those connections works.

 

It should, the only place that can cut alternator and battery 12-14volts both is the connection at the fuse box, or the main engine ground

If just engine died but dash lights stayed on then could be PCM relay
You can also check the larger fuses in engine fuse box, the 40-60amp fuses
They feed the cab fuse box and ignition switch, so if one lost power it would be like shutting off the key, but long shot on that
Pull them out and look for corrosion

And that takes you to the ignition switch itself, there is just ONE wire that feeds voltage to ignition switch(under steering column)
Its from fuse #9, 40amp, in engine fuse box
If that wire loses power its the same as turning key OFF

 

The problem still exists but now things have....changed.

I just started the truck up fine but just like the first time this problem arose the truck died as I was pulling out of the driveway only this time the PATS icon is lit up on the dash. If I put my foot on the brake the PATS icon goes away but the truck wont start. If I take the key out and my foot off the brake the PATS icon is illuminated solid. Nothing works, no lights, no radio, no accessories, nothing. I tried my spare key and it does not work, does the same thing PATS icon just illuminated solid. How can I reset this stupid PATS system? I think that may be what's killing all power to the vehicle.

After waiting 10 minutes I tried to start the truck again and when I removed the key the PATS system blinked 3 times, pause, then it just blinks and blinks like it's trying to give some sort of fault code. I can hear a relay clicking in the fuse box that coincides with the blinking. I removed the key and I can hear and see a very faint blinking of the PATS light but it's not flashing.

 

Well the dealer found the problem. Turns out the battery was faulty and was putting out low voltage causing the PATS system to go haywire. The first few times the truck died and lost all power it showed symptoms of a bad ground/connection at the engine or fuse box but in reality it must have been the PATS system killing the vehicle just for a split second.

I knew I should have trusted my gut and replaced the battery since this all started just a few weeks after I replaced the battery but it just did make any sense as to a bad battery causing the problems I was seeing. I'm lucky the dealer was only able to bend me over for $300 on a new battery and cables.

 

Nope, PATS won't kill a running engine, PATS can only prevent an engine from starting.

 

Then I'll rephrase. An electrical short or bad cell in the battery was causing a full loss of power when vehicle was running. Low voltage from the battery caused the PATS system to go into theft mode. Vehicle would not start. Pats light solid, PATS light blinking code upon trying to start vehicle.

The PATS system itself was not responsible for killing the vehicle when running, that was the short in the battery (I think) but the PATS system was responsible for bricking up the vehicle and not allowing it to start. Either way the vehicle is running now after replacing the battery. Hopefully that was in fact the issue and there is not an electrical gremlin still hiding somewhere.