I was gone for about 10 days and when I returned the batteries were totally dead. Only thing drawing power during that time was a Streamlight Stinger flashlight that was plugged in. Anyhow, jumped-it with my tractor, idled awhile and drove about 5 miles to recharge. Next morning, started fine.

My question: The check engine light now appears, which never has before. While out and about in a different auto, I stopped at a Ford dealer and ask how to git rid of the engine light. He said their are 2 ways. Get the dealer to clear the memory for the engine light with a computer. The second way is what I'm really asking about, which got my attention. Disconnect the cables on both batteries, make sure the cables are not touching the batteries, then touch the pos to the neg together (cables only) for about 10 seconds. Do this on both sets of battery cables, one at a time. This will ground out the memory of whatever problem you have, which includes the check engine light.

Has anyone ever done this or heard of this? He (the dealer) said it works and is safe to do. Only problem will be setting the clock and radio stations again. I don't want to do something that's harmful, that's why I'm asking.

Hope this makes since the way I explained it. Thanks

 

Not sure of the benefit of "completing" the circuit this way. Maybe they are thinking that residual power can be drained from any onboard capacitors residing on the electronic circuitry. Typically by leaving the cables disconnected for several minutes, any residual current will drain.

Maybe someone with more familiarity with the Ford electronics can speak to the subject, but it makes no sense to me.

 

Um.. that is the Standard Operating Procedure I issue for people to reset the computers.

It will not kill a CEL that is in Non Volatile Memory, but it will reset the computers.

You are actually suppose to turn the headlight on, then short the cable ends after both batteries are disconnected.

All the learning (transmission etc.) has to be done all over again.

 

As it turned out, when I started up this morning the light was gone, apparently on it's on. I guess it sets itself after a while. Still am very curious about the battery cable thing. I think gearloose1 tried to explain, but it kinda went over my head. Thanks

 

It works. I've done it on other vehicles.

 

Hi Sandy,

You really should get it checked out. Simply assuming that the CEL is due to the batteries being discharged probably isn't a good idea.

There are a LOT of things that can cause a CEL, and this only comes on when the truck has something to tell you. The only way to find out is to get the codes scanned by the dealer.

If it went off and then on again after some time there is likely something wrong that's causing the code to get set again.

I highly recommend focusing less on clearing the code and more on finding the problem! Take it to the dealer, they will diagnose and repair for free under warranty.

 

I'll get it checked out next week to make sure of no other problems. Thanks

 

The other way is to have your own scan tool.

A basic scan tool can be as little as $20, it will not read the more advanced stuff, but it is better than nothing.

My $25 code reader will reset codes for me.


Certain codes can come, and go away on their own.

For example, on gassers, the code set by the fuel filler cap loose (admitting air) will self reset once the cap is properly tightened.

Likewise, other codes, such as what the OP described above, is likely a "low voltage" code that is set when the batteries are drained flat.

Recharging the batteries will cause the code to self reset (without the above computer reset procedure, which in fact, do not clear many codes stored in non-volatile memory).

Quite frankly, 5 miles is not enough to recharge dead flat batteries, and you probably had a low voltage warning.


While no harm is done when the vehicle is under warranty to take it in.. it is a few hours out of your life... if you have better things to do.


Right now, Sandy, you have a "it ain't broke" situation....

Don't send it to Ford to "fix" it.

Wait for a normal maintenance interval.

Meanwhile... don't run your batteries down again, buy a good charger, and fully charge the batteries.

You do need to recharge your batteries now.

@10 amp an hour, that is going to take 24 hours for 2 dead batteries.

 

As gearloose pointed out but it bears repeating, make sure both batteries are totally disconnected prior to touching the cables together, if not, you will be in for one shocking experiance!

Yes, that should work.