Service Information

Volt

DTC P151C or P2516-P2518

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 P151C: Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Not Plausible

DTC P2516: Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Performance

DTC P2517: Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Circuit Low Voltage

DTC P2518: Air Conditioning (A/C) Low Side Refrigerant Pressure Sensor Circuit High Voltage

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
5 V Reference	P2516 00 P2517 00	P2516 00 P2517 00	--	--
Signal	P2516 00 P2517 00	P2516 00 P2517 00	P2516 00 P2518 00	-
Low Reference	--	P2516 00 P2517 00	--	--

Circuit/System Description

The Hybrid Powertrain control module (HPCM2) monitors the low side refrigerant pressure through the A/C pressure sensor. The HPCM2 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 HPCM2 to vary. When the pressure is high, the signal voltage is high. When the pressure is low, the signal voltage is low.

Conditions for Running the DTC

P151C

•	12 V battery system voltage above 10.25 V.

•	HPCM2 is awake and communicating.

•	None of these DTCs may be active: P2517, P2518, P0073; P0072; P0071, P0119; P0118; P0117; P0116, P0531, P0532; P0533, P537,P538, P153B, P0606

•	Outside Air Temperature raw and corrected values must have had a chance to settle out. Once this occurs these variables are assigned a status of valid. May need to have some time driving in EV mode

•	Engine coolant temperature must be within 15 degrees of outside air temperature

•	Outside Air Temperature between 0°C (32°F) and 25°C (77°F).

•	AC compressor must have been off for an hour since the last time the AC compressor was on.

P2516

•	12 V battery system voltage above 10.25 V.

•	HPCM2 is awake and communicating.

•	None of these DTCs may be active: P2517, P2518, P0073; P0072; P0071, P0119; P0118; P0117; P0116, P0606

•	Engine coolant temperature must be within 15 degrees of outside air temperature

•	AC compressor must have been off for an hour since the last time the AC compressor was on.

•	AC compressor must be turned on for one minute. (This may the require the service technician to select an HVAC mode that causes the AC compressor to run).

P2517 or P2518

•	12 V battery system voltage above 10.25 V.

•	HPCM2 is awake and communicating.

Conditions for Setting the DTC

DTC P151C

The A/C low side Refrigerant Pressure reading and the A/C high side Refrigerant Pressure reading must be within 200 kPa (29 psi). and the A/C low side Refrigerant Pressure reading and the pressure derived from the A/C Refrigerant Temperature Sensor must be within 200 kPa (29 psi)

DTC P2516

The difference between the A/C low side pressure Sensor before compressor on and after compressor on changes less than 50 kPa (7 psi) over a 15 second period.

DTC P2517

The HPCM2 detects a short to ground or open at the A/C low side pressure sensor signal circuit.

DTC P2518

The HPCM2 detects a short to voltage at the A/C low side pressure sensor signal circuit.

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 Testing

Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the B1C A/C low side pressure sensor harness connector. It may take up to 2 minutes for all vehicle systems to power down.
Test for less than 10 Ω between the low reference circuit terminal 3 and ground.

⇒	*If 10 Ω or greater*

2.1.	Vehicle OFF, disconnect the harness connector at the K114B HPCM2.

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 K114B HPCM2.

⇓	*If less than 10 Ω*

Vehicle in Service Mode.
Test for 4.8-5.2 V between the 5 V reference circuit terminal 2 and ground.

⇒	*If less than 4.8 V*

4.1.	Vehicle OFF, disconnect the harness connector at the K114B HPCM2.

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 K114B HPCM2.

⇒	*If greater than 5.2 V*

4.1.	Vehicle OFF, disconnect the harness connector at the K114B HPCM2, vehicle in Service Mode.

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 K114B HPCM2.

⇓	*If between 4.8-5.2 V*

Verify the scan tool A/C Low Side Pressure Sensor parameter is less than 4.8-5.2 V.

⇒	*If 4.8-5.2 V or greater*

5.1.	Vehicle OFF, disconnect the harness connector at the K114B HPCM2, vehicle in Service Mode.

5.2.	Test for less than 1 V between the signal circuit terminal 3 and ground.

⇒	If 1 V or greater, repair the short to voltage on the circuit.

⇒	If less than 1 V, replace the K114B HPCM2.

⇓	*If less than 4.8-5.2 V*

Install a 3 A fused jumper wire between the signal circuit terminal 1 and the 5 V reference circuit terminal 2.
Verify the scan tool A/C Low Side Pressure Sensor parameter is greater than.02 V.

⇒	*If.02 V or less*

7.1.	Vehicle OFF, disconnect the harness connector at the K114B HPCM2.

7.2.	Test for infinite resistance between the signal circuit terminal 1 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 K114B HPCM2.

⇓	*If greater than.02 V*

Test or replace the B1C A/C refrigerant pressure sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	HVAC Component Replacement Reference

•	Control Module References for control module replacement, programming and setup