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• | 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
5V Reference | P0530 03, P0532 00 | P0530 03, P0532 00 | -- | -- |
Refrigerant Pressure Sensor Signal | P0530 03, P0532 00 | P0530 03, P0532 00 | P0530 07, P0533 00 | - |
Low Reference | -- | P0530 03, P0532 00 | -- | -- |
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. 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 activation of the A/C compressor.
Engine is running.
The ECM detects a short to ground or open at the A/C pressure sensor signal circuit.
The ECM detects a short to voltage at the A/C pressure sensor signal circuit.
• | The A/C compressor is disabled. |
• | The ECM will illuminate the malfunction indicator lamp (MIL). |
The condition for setting the DTC is no longer present.
Automatic HVAC Description and Operation
Control Module References for scan tool information
If less than 4.8 V
2.1. | Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. |
2.2. | 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
2.3. | 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
2.1. | Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. |
2.2. | Ignition ON, test for less than 0.3 V between the 5 V reference circuit and ground. |
If greater than 0.3 V, repair the short to voltage on the circuit.
If less than 0.3 V, replace the K20 Engine Control Module.
If within 4.8-5.2 V
If less than 4.8 V
3.1. | Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. |
3.2. | 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 greater than 5.2 V
3.1. | Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. |
3.2. | Ignition ON, test for less than 0.3 V between the low reference circuit and ground. |
If greater than 0.3 V, repair the short to voltage on the circuit.
If less than 0.3 V, replace the K20 Engine Control Module.
If within 4.8-5.2 V
If greater than 0.3 V
4.1. | Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. |
4.2. | Ignition ON, test for less than 0.3 V between the signal circuit terminal 3 and ground. |
If greater than 0.3 V, repair the short to voltage on the circuit.
If less than 0.3 V, replace the K20 Engine Control Module.
If less than 0.3 V
If less than 4.8 V
5.1. | Ignition OFF, disconnect the harness connector at the K20 Engine Control Module. |
5.2. | 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
5.3. | 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
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for engine control module (ECM) replacement, setup, and programming |
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