1A-226 Engine Control System (4HK1)
DTC P0651 (Flash Code 56)
Circuit Description
The ECM provides 5 volts reference voltage through
the reference circuit 2 to the following sensors:
• Accelerator pedal position (APP) sensor 2
• Barometric pressure (BARO) sensor
• Intake air temperature (IAT) sensor
The ECM also provides 5 volts reference voltage
through the reference circuit 5 to the following sensors:
• Fuel rail pressure (FRP) sensor
• Camshaft position (CMP) sensor
• EGR position sensor
The 5 volts reference circuits 2 and 5 are independent
of each other outside of the ECM, but are bussed
together inside the ECM. Therefore, a short circuit
condition on one sensor 5 volts reference circuit may
affect the entire 5 volts reference circuit 2 and 5. The
ECM monitors the voltage on the 5 volts reference
circuit 2 and 5. If the ECM detects the voltage is
excessively low or high, this DTC will set.
Condition for Running the DTC
• DTC P060B is not set.
• The battery voltage is between 18 to 32 volts.
• The ignition switch is ON.
Condition for Setting the DTC
Either of following condition is met:
• The ECM detects that the 5 volts reference circuit
2 or 5 voltage is less than 4.5 volts.
• The ECM detects that the 5 volts reference circuit
2 or 5 voltage is more than 5.5 volts.
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.
• The ECM blinks the exhaust brake indicator lamp
when the diagnostic runs and fails.
• The ECM limits fuel injection quantity.
• The ECM inhibits pilot injection.
• The ECM inhibits EGR control.
• The ECM inhibits exhaust brake control.
Condition for Clearing the DTC
• Refer to DTC Type Definitions for Condition for
Clearing the MIL/ DTC - Type A.
Diagnostic Aids
• If an intermittent condition is suspected, refer to
Intermittent Conditions in this section.
Notice:
If this DTC is set, the engine cranks but does
not start.
Schematic Reference:
Engine Controls Schematics
Connector End View Reference:
Engine Controls
Connector End Views or ECM Connector End Views
Circuit/ System Testing DTC P0651
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.
Install a scan tool.
2.
Turn OFF the ignition for 30 seconds.
3.
Start the engine.
4.
Monitor the DTC Information with a scan tool.
Does the DTC fail this ignition?
—
Go to Step 3
Go to Diagnostic
Aids
3
1.
Turn OFF the ignition.
2.
Disconnect the EGR valve harness connector.
3.
Connect a DMM between the 5 volts reference
circuit (pin 1 of E-15) and a known good
ground.
4.
Turn ON the ignition, with the engine OFF.
Is the DMM voltage less than the specified
value?
5.5 volts
Go to Step 4
Go to Step 10
4
Is the DMM voltage more than the specified
value at Step 3?
4.5 volts
Go to Step 11
Go to Step 5
LG4HKED-WE-0871.book 226
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