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Tahoe / Yukon Service Manual

DTC P0532 or P0533

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 the 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 Short to Ground Open/High Resistance Short to Voltage Signal Performanc
5 V Reference P0532 P0532 P0533 —
Signal P0532 P0532 P0533 —
Low Reference — P0533 — —

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 V 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. The ECM may use this information to turn the cooling fans on as well as to monitor clutch engagement. The HVAC module will receive the A/C refrigerant pressure information from the ECM via serial data. Conditions for Running the DTC The ECM monitors the signal circuit voltage every 25 ms. Any of the conditions for setting the DTC are met for 80 out of 100 samples. Conditions for Setting the DTC P0532 The ECM detects that the A/C pressure signal is less than 0.15 V. P0533 The ECM detects that the A/C pressure signal is more than 4.75 V. Action Taken When the DTC Sets DTC Type C The A/C compressor is disabled. Conditions for Clearing the DTC DTC Type C 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 Master Electrical Component List Description and Operation Automatic HVAC Description and Operation 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 Control Module References for scan tool information Circuit/System Verification

  1. Install the appropriate Air Conditioning Service Center, ignition ON
  2. Verify the high side pressure on the gauge is within 10% of the scan tool A/C High Side Pressure Sensor parameter. ⇒ If the A/C High Side Pressure Sensor parameter is not within 10% Refer to Circuit/System Testing. ⇓ If the A/C High Side Pressure Sensor parameter is within 10%
  3. Verify the A/C High Side Pressure Sensor parameter is between 269−2929 kPa (39−425 PSI). ⇒ If the reading is not between 269−2929 kPa (39−425 PSI) Refer to Air Conditioning (A/C) System Performance Test ⇓ If the reading is between 269−2929 kPa (39−425 PSI)
  4. All OK Circuit/System Testing
  5. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the B1 Air Conditioning Refrigerant Pressure Sensor. It may take up to 10 min for all vehicle systems to power down.
  6. Test for less than 10 Ω between the low reference circuit terminal 3 and ground. ⇒ If 10 Ω or greater 2.1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. 2.2. Test for less than 2 Ω in the low reference circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K20 Engine Control Module. ⇓ If less than 10 Ω
  7. Ignition ON.
  8. Test for 4.8–5.2 V between the 5 V reference circuit terminal 1 and ground. ⇒ If less than 4.8 V 4.1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. 4.2. Test for infinite resistance between the 5 V reference circuit and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇓ If infinite resistance 4.3. Test for less than 2 Ω in the 5 V reference circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K20 Engine Control Module. ⇒ If greater than 5.2 V 4.1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON. 4.2. Test for less than 1 V between the 5 V reference circuit and ground. ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the K20 Engine Control Module. ⇓ If between 4.8–5.2 V
  9. Verify the scan tool A/C High Side Pressure Sensor parameter is less than .25 V. ⇒ If .25 V or greater 5.1. Ignition OFF, disconnect the harness connector at the K20 Engine Control Module, ignition ON. 5.2. Test for less than 1 V between the signal circuit terminal 2 and ground. ⇒ If 1 V or greater, repair the short to voltage on the circuit. ⇒ If less than 1 V, replace the K20 Engine Control Module. ⇓ If less than .25 V
  10. Install a 3 A fused jumper wire between the signal circuit terminal 2 and the 5 V reference circuit terminal 1.
  11. Verify the scan tool A/C High Side Pressure Sensor parameter is greater than 4.8 V. ⇒ If 4.8 V or less 7.1. Ignition OFF, remove the jumper wire, disconnect the harness connector at the K20  Engine Control Module. 7.2. Test for infinite resistance between the signal circuit and ground. ⇒ If less than infinite resistance, repair the short to ground on the circuit. ⇓ If infinite resistance 7.3. Test for less than 2 Ω in the signal circuit end to end. ⇒ If 2 Ω or greater, repair the open/high resistance in the circuit. ⇒ If less than 2 Ω, replace the K20 Engine Control Module. ⇓ If greater than 4.8 V
  12. Test or replace the B1 Air Conditioning Refrigerant Pressure Sensor. Repair Instructions Perform the Diagnostic Repair Verification after completing the repair. HVAC Component Replacement Reference Control Module References for control module replacement, programming and setup