How to really reset ECU????? besides disconnecting battery. - Toyota Yaris Forums

marcus · 11-17-2010, 06:36 PM

How to really reset ECU????? besides disconnecting battery.

i was told disconnecting battery for an hour or a day doesnt really reset ecu!!!

severous01 · 11-17-2010, 07:55 PM

disconnect negative terminal and connect it to positive via short test cable...or apply brakes and lights while battery is disconnected.

why you resetting pcm?

CTScott · 11-17-2010, 08:51 PM

Modern ECMs use flash ROM instead of CMOS RAM to store data. With our ECM, you can leave it unplugged for a year and you won't clear stored DTCs or the long term settings. On the other hand, it does clear the short term fuel trim when it is rebooted (by disconnecting the battery or pulling connector A21 {the smaller ECM connector}). This reset literally takes seconds, as the ECM has very little capacitance to keep the processor alive when power is removed.

There is an initialization that can be done via CAN bus using the TechStream tool. This procedure clears the long term data:

INITIALIZATION
1. RESET MEMORY
NOTICE:
• Perform the RESET MEMORY (AT initialization)
when replacing the automatic transaxle assembly,
engine assembly or ECM.
• The RESET MEMORY can only be performed
using an intelligent tester.
HINT:
The ECM stores the conditions that the ECT controls the
automatic transaxle assembly and engine assembly in
accordance with those characteristics. Therefore, when
the automatic transaxle assembly, engine assembly, or
ECM is replaced, it is necessary to reset the memory so
that the ECM can store the new information.
The reset procedure is as follows.
(a) Turn the ignition switch off.
(b) Connect the intelligent tester to the DLC3.
(c) Turn the ignition switch to the ON position and push
the intelligent tester main switch on.
(d) Select the following items: DIAGNOSIS /
ENHANCED OBD II.
(e) Perform the reset memory procedure from the
ENGINE menu.

marcus · 11-17-2010, 11:57 PM

want to reset my mpg..its getting pretty low since i been driving pretty aggressive recently want to start over.

and thats pretty detailed ctscott..but i dont have the tools for it.

CTScott · 11-18-2010, 10:24 AM

Quote:

Originally Posted by marcus

want to reset my mpg..its getting pretty low since i been driving pretty aggressive recently want to start over.

and thats pretty detailed ctscott..but i dont have the tools for it.

Well, the semi good news is that you will be able to do that reset with my YarGauge.

11-17-2010, 06:36 PM	#1
marcus toyota View User's Garage Drives: 2007 Yaris RS Blazed Join Date: Oct 2006 Location: toronto, canada Posts: 3,637	How to really reset ECU????? besides disconnecting battery. How to really reset ECU????? besides disconnecting battery. i was told disconnecting battery for an hour or a day doesnt really reset ecu!!!

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11-17-2010, 07:55 PM	#2
severous01 Drives: 2008 yaris, stripped, red Join Date: Jan 2009 Location: SE Texas Posts: 977	disconnect negative terminal and connect it to positive via short test cable...or apply brakes and lights while battery is disconnected. why you resetting pcm?

11-17-2010, 08:51 PM	#3
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	Modern ECMs use flash ROM instead of CMOS RAM to store data. With our ECM, you can leave it unplugged for a year and you won't clear stored DTCs or the long term settings. On the other hand, it does clear the short term fuel trim when it is rebooted (by disconnecting the battery or pulling connector A21 {the smaller ECM connector}). This reset literally takes seconds, as the ECM has very little capacitance to keep the processor alive when power is removed. There is an initialization that can be done via CAN bus using the TechStream tool. This procedure clears the long term data: INITIALIZATION 1. RESET MEMORY NOTICE: • Perform the RESET MEMORY (AT initialization) when replacing the automatic transaxle assembly, engine assembly or ECM. • The RESET MEMORY can only be performed using an intelligent tester. HINT: The ECM stores the conditions that the ECT controls the automatic transaxle assembly and engine assembly in accordance with those characteristics. Therefore, when the automatic transaxle assembly, engine assembly, or ECM is replaced, it is necessary to reset the memory so that the ECM can store the new information. The reset procedure is as follows. (a) Turn the ignition switch off. (b) Connect the intelligent tester to the DLC3. (c) Turn the ignition switch to the ON position and push the intelligent tester main switch on. (d) Select the following items: DIAGNOSIS / ENHANCED OBD II. (e) Perform the reset memory procedure from the ENGINE menu.

11-17-2010, 11:57 PM	#4
marcus toyota View User's Garage Drives: 2007 Yaris RS Blazed Join Date: Oct 2006 Location: toronto, canada Posts: 3,637	want to reset my mpg..its getting pretty low since i been driving pretty aggressive recently want to start over. and thats pretty detailed ctscott..but i dont have the tools for it.