Does this computer system have a battery back-up? When the vehicles battery is disconnected, does that erase any stored codes/RAM, or is there a battery back-up to keep the computer powered? Thanks
Dave S(Texas)
There is Firmware that stores the program. As to the particular settings of the firmware variables, I am not sure if that is stored after the battery is disconnected or not. In any case, after about 20 minutes, the variable settings are re-learned by the firmware, and the computer will right itself.
Why do you ask?
Computers use two types of memory, RAM and ROM. ROM holds with no power, RAM looses when power gone. The actual program is stored in ROM, things like codes in RAM. ROM is Read Only Memory, RAM is Random Access Memory.
Whitelightning
No battery back-up
When the vehicles
Yes , codes set are no longer readable
NO
Yes, ROM contains the firmware. Firmware acts like BIOS, it tells the computer what to do. RAM is where datta generated and collected by the firmware gets stored. The firmware has default values that are not erased, but can be updated and the updated values are stored in RAM. The RAM can be erased, in which case the computer will revert to the default value(s) until such time as new variables are stored. Some default values are not subject to being updated, other values are constantly updated.
Did you mean to give me a refresher course on computer memory?
On Sat, 10 Mar 2007 09:18:07 -0600, putt rearranged some electrons to form:
No. Disconnecting the battery erases any stored codes, and variables that are specific to the vehicle. The program re-learns the variables after a period of time.
No.
Codes are cleared.
All trouble codes are written to a non-volatile memory. The right scan tool can retrieve all codes from history that were set from the day the PCM was first powered up.
All the answer posts confirm what I know to be true on the OBD1 system.....I have one of those. I wasn't sure about the newer OBD version.
Reason: happened to watch a 'Two Guys Garage' show. They were checking out a used Ford car and the first thing they did was disconnect the battery cable for cleaning. The next thing they did was plug in a scanner and read a 'misfire' code! Since they did it in that sequence I wondered about battery back-up power. Sam lied....lol Thanks
Dave S(Texas)
No the original poster.
Whitelightning
No, Sam Memmolo is an idiot.
On Sat, 10 Mar 2007 16:07:16 -0600, putt rearranged some electrons to form:
Sounds like a continuity error. Their editor should be fired.
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