QUOTE(super8 @ Nov 26 2012, 05:39 PM)
Hi cbinn, can advise on the step to disconnect 12v battery and rev 2.5k in neutral for the recal issue. Should start the engine 1st then disconnect the 12v battery and so on or don't start engine and disconnect 12v battery...
Copied from what is written in Insighters Malaysia Facebook page, lazy to type all over again, credit to all the Insighters who had contributed in discussion:
Most mechanic will simply change the 12v with your engine running. Reason being, even during the 12v batt being disconnected, all the electronics like the clock, radio and ecu still receive continuous 12v supply from the running alternator (the dc-dc converter in the case of insight), thus all setting and memory would be retained.
So, whats bad if memory not retained? For clock and radio, it would be the trouble of reprogramming the time and station. As for the ecu side, not really that harmful except you may get rough engine and transmission for the first few journey after battery change, till the ecu relearn all the setting like fuel curve by itself. Otherwise you suppose to perform at least Idle Relearn and Crank Pattern Relearn procedure. hybrid have one more extra issue. the bcm or battery control module memory is lost means it will trigger recalibration routine. then you will get cases where the state of charge being full one minute, and without much assist, the soc will suddenly drops to complete 0 and ima keep on staying on regen mode making the car felt sluggish. this will go on a few cycle depending on the condition of the ima pack till the bcm determined that the soc being recalibrated properly.
Have some 1 told if u dun want reset everything, change the 12v battery while car started. Is that true?
True but just have to be very careful. Lots of moving things when engine running, and reversing the polarity or accidentally touching wrong cable at wrong place can be very very damaging to entire car electronics because everything is 'alive' when engine is running.
So the best way still is stop the car to avoid any unnecessary damage?
Best is to let experienced mechanic do it, whether to change with engine running or attach a backup battery before performing the change, you still need to do it properly and carefully to avoid unnecessary damage. Modern cars have plenty of electronics, not to mention ours have even more because of the hybrid system.
Got this paragraph from the internet. Removing 12V may cause ECU to be reset / memory loss, and if you do not recalibrate the CVT's start-up clutch 'release' position after ECU reset, you may get high fuel consumption during the first few drive. Because engagement of the start-up clutch (when you shift from P or N into D) is via hydraulics and activated by the ECU via sensors, once you reset the ECU, you need to let it detect when the start-up clutch is at full engage (what they call 'lock-up') and when it's at full release. The best way to do this is to get your service center to do it as there is a specific procedure for it. If you don't, the ECU may not have the start-up clutch in the fully released or fully engaged positions when it needs to be and you may end up with very bad fuel consumption. This has actually been reported by a number of owners who resetted their ECU without doing the proper re-calibration procedure. They reported very bad fuel consumption but it was solved after the SC did the proper recalibration procedure for them. In my opinion people resetting the ECU but not recalibrating the CVT may also possibly be one of the reasons for some of the small numbers of start-up clutch failure that has been reported.
paultan.org written this for City, but also applicable for other Honda CVT like Jazz and Insight.
http://paultan.org/2005/09/04/honda-city-c...osition-memory/