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Chevrolet Silverado / GMC Sierra. Manual - part 2431
ENGINE COOLANT TEMPERATURE GAGE INACCURATE OR INOPERATIVE
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
The instrument panel cluster (IPC) displays the engine coolant temperature as determined by the
engine control module (ECM). The ECM sends the temperature data via high speed GMLAN
serial data to the body control module (BCM). The BCM then sends the information via low
speed GMLAN to the IPC in order to display the engine temperature.
Reference Information
Schematic Reference
Instrument Cluster Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Instrument Cluster Description and Operation
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Ignition ON, perform the engine coolant gage sweep test with the scan tool. Verify that the
engine coolant temperature gage sweeps from its low to high position.
If the engine coolant gage does not sweep from its low to high position, replace the IPC.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for IPC replacement, setup, and programming
ENGINE OIL PRESSURE INDICATOR MALFUNCTION
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The engine oil pressure (EOP) sensor changes voltage based on the engine oil pressure. The EOP
sensor is a 3-wire sensor comprising of the signal circuit, the low reference circuit and the 5-volt
reference circuit. The engine control module (ECM) supplies 5 volts to the EOP sensor via the 5-
volt reference circuit and provides ground via the EOP low reference circuit. The ECM monitors
the signal circuit of the EOP sensor to determine the EOP sensor voltage is within the normal
operating range of approximately 1-4 volts. When the engine oil pressure is high, the EOP sensor
voltage is high and the ECM senses a high signal voltage. When the engine oil pressure is low, the
Circuit
Short to
Ground
High
Resistance
Open
Short to
Voltage
Signal
Performance
Engine Oil
Pressure 5-
Volt Reference
P0522
1
P0522
P0523
P0521
Engine Oil
Pressure
Sensor Signal
P0522
1
P0522
P0523
P0521
Low Reference
-
1
P0523
-
P0521
1. Engine Oil Pressure Indicator Malfunction
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
EOP sensor voltage is low and the ECM senses a low signal voltage. The ECM sends the EOP
information via high speed GMLAN to the body control module (BCM). The BCM then sends
the EOP information to the instrument panel cluster (IPC) via low speed GMLAN serial data.
Reference Information
Schematic Reference
Instrument Cluster Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Instrument Cluster Description and Operation
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
1. Engine running, observe the scan tool Engine Oil Pressure Sensor parameter. The reading
should be between 41-448 kPa (6-65 psi).
2. Verify the engine oil pressure, refer to Oil Pressure Diagnosis and Testing .
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the engine oil pressure (EOP) sensor.
2. Ignition OFF, test for less than 1.0 ohm between the low reference circuit terminal 1 and
ground.
If greater than the specified range, test the low reference circuit for an open/high
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
resistance. If the circuit tests normal, replace the ECM.
3. Ignition ON, test for 4.8-5.2 volts between the 5-volt reference circuit terminal 2 and
ground.
If less than the specified range, test the 5-volt reference circuit for a short to ground or
an open/high resistance. If the circuit tests normal, replace the ECM.
If greater than the specified range, test the 5-volt reference circuit for a short to
voltage. If the circuit tests normal, replace the ECM.
4. Verify the scan tool Engine Oil Pressure Sensor parameter is less than 8 kPa (1.2 psi).
If greater than the specified range, test the signal circuit terminal 3 for a short to
voltage or an open/high resistance. If the circuit tests normal, replace the ECM.
5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5-volt reference
circuit terminal 2. Verify the scan tool Engine Oil Pressure Sensor parameter is greater than
550 kPa (80 psi).
If less than the specified range, test the signal circuit for a short to ground or an
open/high resistance. If the circuit tests normal, replace the ECM.
6. If all circuits test normal, test or replace the EOP sensor.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Engine Oil Pressure Sensor and/or Switch Replacement for the 4.3L engine
Engine Oil Pressure Sensor and/or Switch Replacement for the 4.8L, 5.3L, 6.0L, and
6.2L engines
Engine Oil Pressure Sensor and/or Switch Replacement for the 6.6L engine
Control Module References for ECM replacement, setup, and programming
FUEL GAGE INACCURATE OR INOPERATIVE (SINGLE TANK)
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Short to
High
Short to
Signal
2008 Chevrolet Silverado 1500
2008 ACCESSORIES & EQUIPMENT Displays and Gages - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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