1A-250 Engine Control System (4HK1)
DTC P1621 (Flash Code 54)
Circuit Description
This diagnostic applies to internal microprocessor
integrity conditions within the ECM.
Condition for Running the DTC
• The ignition switch is ON.
Condition for Setting the DTC
• The ECM detects that the calculated checksum
does not agree with the electrically erasable &
programmable read only memory (EEPROM)
internal registered checksum.
Action Taken When the DTC Sets
• The ECM illuminates MIL when the diagnostic runs
and fails. Refer to DTC Type Definitions for Action
Taken When the DTC Sets - Type A.
Condition for Clearing the DTC
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A.
Circuit/ System Testing DTC P1621
Step
Action
Value(s)
Yes
No
1
Did you perform the Diagnostic System Check
- Engine Controls?
—
Go to Step 2
Go to Diagnostic
System Check -
Engine Controls
2
1.
Ensure that all tool connections are secure.
2.
Ensure that programming equipment is
operating correctly.
3.
Install a scan tool.
4.
Turn OFF the ignition for 30 seconds.
5.
Turn ON the ignition, with the engine OFF.
6.
Monitor the DTC Information with a scan tool.
Does the DTC fail this ignition?
—
Go to Step 3
Go to Step 4
3
Important:
Replacement ECM must be
programmed and learned.
Replace the ECM. Refer to ECM Replacement.
Did you complete the replacement?
—
Go to Step 4
—
4
1.
Clear the DTCs with a scan tool.
2.
Turn OFF the ignition for 30 seconds.
3.
Start the engine.
4.
Operate the vehicle within the Conditions for
Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/ Failure
Records.
Did the DTC fail this ignition?
—
Go to Step 3
Go to Step 5
5
Observe the DTC Information with a scan tool.
Are there any DTCs that you have not
diagnosed?
—
Go to DTC List
System OK
LG4HKED-WE-0871.book 250
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