Content .. 2348 2349 2350 2351 ..
Chevrolet Silverado / GMC Sierra. Manual - part 2350
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.
DTC Descriptors
DTC P0532
Air Conditioning A/C Refrigerant Pressure Sensor Circuit Low Voltage
DTC P0533
Air Conditioning A/C Refrigerant Pressure Sensor Circuit High Voltage
Diagnostic Fault Information
Circuit/System Description
The engine control module (ECM) monitors the high side refrigerant pressure through the A/C
refrigerant pressure sensor. The ECM supplies a 5-volt reference and a low reference to the
sensor. Changes in the A/C refrigerant pressure cause the sensor signal to the ECM to vary. When
the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low.
When pressure is high, the ECM commands the cooling fans on. When pressure is too high or too
low, the ECM will not allow the A/C compressor clutch to engage.
Conditions for Running the DTC
Engine is running.
Any of the conditions for setting the DTC are met for 15 seconds.
Battery voltage is between 11-18 volts.
Conditions for Setting the DTC
The ECM detects that the A/C pressure is less than 1 psi (0.01 volt) sets DTC P0532.
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Signal
Performance
5-Volt Reference
P0532
P0532
-
-
A/C Refrigerant Pressure Sensor
Signal
P0532
P0532
P0533
-
Low Reference
-
P0533
-
-
2008 Chevrolet Silverado 1500
2008 HVAC HVAC - Manual - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
The ECM detects that the A/C pressure is more than 428 psi (4.92 volts) sets DTC P0533.
Action Taken When the DTC Sets
The ECM will not illuminate the malfunction indicator lamp (MIL).
The ECM stores the Failure Records.
The A/C compressor clutch is disabled.
Conditions for Clearing the DTC
The history DTC will clear after 40 consecutive ignition cycles have occurred without a
malfunction.
The DTC will become history if the ECM no longer detects a failure.
Diagnostic Aids
A malfunction within the refrigerant system causing high pressure can cause this DTC to set.
Reference Information
Schematic Reference
HVAC Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Air Temperature Description and Operation
Air Delivery Description and Operation
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
2008 Chevrolet Silverado 1500
2008 HVAC HVAC - Manual - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Control Module References for scan tool information
Circuit/System Verification
Ignition ON, observe the scan tool A/C Pressure Sensor parameter. The reading should be
between 0.1 volts (1 psi) and 4.90 volts (425 psi) and change with A/C refrigerant pressure
changes.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the A/C refrigerant pressure sensor.
2. Ignition OFF, test for less than 10 ohms between the low reference circuit terminal 1 and
ground.
If greater than the specified range, test the low reference circuit for an open/high
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 A/C High Side Pressure Sensor parameter is less than 0.1 volts (1 psi).
If greater than the specified range, test the signal circuit terminal 3 for a short to
voltage. 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 A/C High Side Pressure Sensor parameter is greater
than 4.90 volts (425 psi).
If less than the specified range, test the signal circuit for 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 A/C refrigerant pressure sensor.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Air Conditioning (A/C) Refrigerant Pressure Sensor Replacement (Non-HP2)
Control Module References for the ECM replacement, setup, and programming
DTC P0645
2008 Chevrolet Silverado 1500
2008 HVAC HVAC - Manual - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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.
DTC Descriptor
DTC P0645
A/C Clutch Relay Control Circuit
Diagnostic Fault Information
Circuit System Description
Ignition voltage is supplied directly to the A/C compressor clutch relay. The engine control
module (ECM) controls the relay by grounding the A/C clutch relay control circuit. When the
ECM is commanding a component ON, the voltage of the control circuit should be near 0 volt.
When the ECM is commanding the control circuit to a component OFF, the voltage potential of
the circuit should be near battery voltage.
Conditions for Running the DTC
The ignition voltage is between 11-18 volts.
The engine speed is greater than 600 RPM.
An A/C request is made.
Conditions for Setting the DTCs
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Signal
Performance
B+
1
1
-
-
A/C Relay Coil Side Supply
Voltage
1
1
-
-
Ignition 1
1
1
-
-
A/C Compressor Clutch Relay
Control
P0645
P0645
P0645
-
A/C Relay Coil Side Ground
-
1
-
-
1. A/C Compressor Inoperative
2008 Chevrolet Silverado 1500
2008 HVAC HVAC - Manual - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Content .. 2348 2349 2350 2351 ..