Suzuki XL7 2007 Service Manual page 242

1A-137 Engine General Information and Diagnosis:
Circuit/System Description
The engine control module (ECM) has 3 5-volt reference
circuits. The ECM provides the 5-volt reference to
various sensors. Each reference circuit provides a 5-volt
reference for more than one sensor. A short to ground or
voltage on one of the 5-volt reference circuits will affect
all components connected to that 5-volt reference circuit.
The ECM monitors the voltage on the 5-volt reference
circuits.
Conditions for Running the DTC
• The ignition is ON for more than 3 seconds.
• DTCs P0642 and P0643 run continuously when the
above condition is met.
Conditions for Setting the DTC
The 5-volt reference 3 voltage is above or below a
predetermined threshold for more than 4 seconds.
Action Taken When the DTC Sets
DTCs P0642 and P0643 are Type A DTCs.
Conditions for Clearing the DTC
DTCs P0642 and P0643 are Type A DTCs.
Diagnostic Aids
The 5-volt reference 1 circuit provides 5 volts to the
following sensors:
• The fuel tank pressure (FTP) sensor
• The engine oil pressure (EOP) sensor
Reference Information
Schematic Reference
"Engine Controls Schematics"
Connector End View Reference
• "Engine Control Module Connector End Views"
• "Engine Controls Connector End Views"
Electrical Information Reference
• "Circuit Testing: "
• "Connector Repairs: "
• "Testing for Intermittent Conditions and Poor
Connections: "
• "Wiring Repairs: "
DTC Type Reference
"Powertrain Diagnostic Trouble Code (DTC) Type
Definitions"
Scan Tool Reference
• "Scan Tool Data List - Engine Controls - 3.6L (LY7)"
• "Scan Tool Data Definitions - Engine Controls - 3.6L
(LY7)"
• "Scan Tool Output Controls - Engine Controls - 3.6L
(LY7)"
Circuit/System Verification
1. Ignition ON, observe the DTC information with a
scan tool. DTCs P0642 and P0643 should not set.
2. If the vehicle passes the Circuit/System Verification
test, operate the vehicle within the conditions for
running the DTC. You may also operate the vehicle
within the conditions that are captured in the Freeze
Frame/Failure Records List.
Circuit/System Testing
NOTE
Additional DTCs will set when disconnecting
the components.
1. Ignition OFF, disconnect the harness connector of all
appropriate sensors for the applicable DTC. Refer to
Diagnostic Aids.
2. Ignition ON, measure for 4.6-5.2 volts between one
of the 5-volt reference circuits and ground.
➢ If the voltage is less than 4.6 volts, test for a short
to ground on all the 5-volt reference circuits. If all
circuits test normal, replace the control module.
➢ If the voltage is greater than 5.2 volts, test for a
short to voltage on all the 5-volt reference circuits
for each component associated with the
appropriate 5-volt reference circuit. If all circuits test
normal, replace the control module.
NOTE
A short to voltage on the signal circuit of
certain components may cause this DTC to
set.
3. Connect each component associated with the 5-volt
reference 1 circuit one at a time while monitoring the
5-Volt Reference 1 Circuit Status parameter with a
scan tool. The parameter should continue to display
OK.
➢ If the parameter displays Fault when a component
is connected, test the signal circuit of that
component for a short to voltage. If the circuit tests
normal, replace the component.
Repair Instructions
Perform the "Diagnostic Repair Verification - Vehicle
Diagnostic Information: " after completing the diagnostic
procedure.
• "Fuel Tank Pressure Sensor Replacement: "
• "Engine Oil Pressure Sensor and/or Switch
Replacement: "
• "Control Module References: " for ECM replacement,
setup, and programming