If for some reason a truck was taken to the dealer for service work, and the battery was disconnected and then connected 20 min. later and the lights were left on for a couple of days causing a dead battery, could a dealership tech plug in a scan tool to the OBDII port and read the codes? Or must the battery have a charge?

 

Removing power from the ECM will erase any codes that were stored. If your check engine light is not on, then there are no codes in memory.

 

I'm pretty sure that disconnecting the battery will erase the codes.

What I am trying to find out is can the dealer read the PCM with their scan tool if the battery is dead.

 

Depends if it completely killed the battery. It only takes a small amount of power to operate the PCM. The battery may not have died as there is a feature on these that kills power to various(not sure of all) things after 20 mins of non-use. Example: the light under the hood doesn't operate until you open the door, then it re-energizes everything again. If it also kills the power to the headlights after 20 mins then there should have been ample power to hold the codes provided there was a chip plugged in or something to generate a code.

01Lightning, you can still have codes without the "check engine" light. Chips will generate a code and they don't trigger the light.

 

Thanks for your answer.
Maybe I should ask the question a different way. If the battery is removed from the vehicle can a Ford scan tool read a code?

 

NO, My dad is very good friends with an engineer @ ford that works on PCM's, I asked him about this question when my motor blew. He said no way they can get any info after the power has been dissconneted and drained.
Jeff

 

OK,, so how about this question. Does disconnecting the power for a long while and installing the original stock chip erase all remnants of an aftermarket chip. besides the goo on the contacts that is,

if so it sounds like this may be a promising way to hide your mods if you need to take it in for warrenty work.

 

Let me ask this another way. Can a Ford scan tool read the computer of a Lightning if there is no battery in the truck? I know that disconnecting the battery erases codes. But I need to know if the tool needs battery power to operate or if it can read the computer with no power. Thanks for everyones help so far.

 

My guess would be no because in order for a code to exist the PCM would need power to generate one and hold it in it's memory.

 

I may be wrong, but I believe that the NGS tool requires battery power so it could operate. I dont think they are self powered....

 

Thanks Spiro.

 

No. NGS requires battery power from vehicle (through the data link connector)

WDS is a self powered unit but it still requires the vehicle to be powered to initialize communications......

Problem is, by leaving the power off for so long, the notorious p1000 (more driving required) code comes up which would make me a little curious as to why the battery power was removed

 

i can pull the main processor codes form the pcm with my diablo programmer and e-mail them to diablo to modify and put on a chip

 

That sounds cool. So can you come up with your own program to be burnt on a chip?
Jeff

 

i dont have the software to make my own files but i call patrick at diablo for a custom program and they upload it to my website for me to put on the chip