P258B-ELECTRONIC VACUUM PUMP PERFORMANCE
P258B-ELECTRONIC VACUUM PUMP PERFORMANCE
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For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The Electric Vacuum Pump (EVP) system is installed to provide supplemental vacuum to the brake booster, when the engine vacuum supply is low. The pump is connected to the engine and the brake booster through a series of hoses and one-way flow check valves. A pressure sensor, mounted in the brake booster, provides information to the ABS/ESP Module. This information is then sent to the Powertrain Control Module (PCM) over the CAN C BUS. The PCM modulates the EVP operation to maintain the brake booster vacuum within a given range. This system ensures that the customer experiences a consistent brake pedal feel under all driving conditions.
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When Monitored:
With the ignition on and engine running.
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Set Condition:
Minimum Manifold Absolute Pressure (MAP) reading is 15 kpa (4.4 in Hg). EVP minimum vacuum is -35 kpa (-10 in Hg) and the EVP cannot create 3 kpa (1.0 i nHg) or the system cannot increase the vacuum from -35 kpa (-10 in Hg) to -38 kpa (-11 in Hg). Two trip fault. Three good trips to turn off the MIL.
Possible Causes |
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| FUSED B+ CIRCUIT OPEN |
| (T109) ELECTRIC VACUUM PUMP OUTPUT CIRCUIT OPEN |
| (T109) ELECTRIC VACUUM PUMP OUTPUT CIRCUIT SHORTED TO GROUND |
| GROUND CIRCUIT OPEN |
| PINCHED, CUT OR OPEN VACUUM SUPPLY LINE |
| VACUUM PRESSURE SENSOR |
| BRAKE VACUUM BOOSTER |
| ELECTRIC VACUUM PUMP |
| ANTI-LOCK BRAKE SYSTEM (ABS) MODULE |
Always perform the Pre-Diagnostic Troubleshooting procedure before proceeding. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
| NOTE: | Diagnose and repair any communication or low voltage DTCs before proceeding with this test. |
| 1. | Ignition on, engine not running. |
| 2. | With the scan tool, select View DTCs. |
| NOTE: | If DTC P258A is active along with this DTC, perform the diagnostic procedure for P258A before continuing with this DTC. |
Is the DTC Active or Pending at this time?
Yes
- Go To 2
No
- Perform the INTERMITTENT CONDITION diagnostic procedure. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
2. ENGINE WITH ELECTRIC VACUUM PUMP
| 1. | Verify vehicle is equipped with an Electric Vacuum Pump. |
Is the vehicle is equipped with an Electric Vacuum Pump?
Yes
- Go To 3
No
- Go To 13
| 1. | Turn the ignition on. |
| 2. | With the scan tool actuate the Electronic Vacuum Pump. |
Does the Electric Vacuum Pump run?
Yes
- Go To 8
No
- Go To 4
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| 1. | Turn the ignition off. |
| 2. | Remove the EVP Relay from the relay connector harness. |
| 3. | Ignition on, engine not running. |
| 4. | Using a 12-Volt test light connected to ground, probe the Fused B+ circuit in the EVP Relay harness connector. |
Does the test light illuminate brightly?
Yes
- Go To 5
No
- Repair the open or short to ground in the Fused B+ circuit. Inspect and replace the fuse if necessary.
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Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM)
- Standard Procedure).
5. (T109) ELECTRIC VACUUM PUMP OUTPUT CIRCUIT OPEN
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| 1. | Disconnect the Electric Vacuum Pump harness connector. |
| 2. | Measure the resistance of the (T109) Electric Vacuum Pump Output circuit from the EVP Relay socket to the Electric Vacuum Pump harness connector. |
Is the resistance below 5.0 Ohms?
Yes
- Go To 6
No
- Repair the open in the (T109) Electric Vacuum Pump Output circuit.
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Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM)
- Standard Procedure).
6. (T109) ELECTRIC VACUUM PUMP OUTPUT CIRCUIT SHORTED TO GROUND
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| 1. | Measure the resistance between ground and the (T109) Electric Vacuum Pump Output circuit at the EVP Relay socket. |
Is the resistance below 100 Ohms?
Yes
- Repair the short to ground in the (T109) Electric Vacuum Pump Output circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 7
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| 1. | Using a 12-Volt test light connected to 12 Volts, probe the Ground circuit at the Electric Vacuum Pump harness connector. |
Does the test light illuminate brightly?
Yes
- Repair the open in the Ground circuit.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Replace the Electric Vacuum Pump in accordance with the Service Information.
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Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM)
- Standard Procedure).
8. CHECK FOR PINCHED VACUUM SUPPLY LINE
| 1. | Turn the ignition off. |
| 2. | Check the vacuum supply line to brake booster for a pinched, cut or open hose. |
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Go To 9
| 1. | Start the engine. |
| 2. | With the scan tool, view and record the vacuum pressure signal with foot off the brake pedal. |
| 3. | With the scan tool, view the vacuum pressure signal while pressing the brake pedal several times. |
| 4. | Record the highest value. |
Without the brake pedal applied, was the vacuum pressure signal -40 kpa (-12 in Hg)?
Yes
- Go To 10
No
- Replace the Power Brake Booster in accordance with the Service Information. (Refer to 05 - Brakes/Hydraulic/Mechanical/BOOSTER, Power Brake - Removal) .
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
10. CHECK FOR VACUUM PRESSURE SIGNAL CHANGE
| 1. | Turn the ignition on. |
| 2. | Remove the Vacuum Pressure Sensor from the Booster. |
| 3. | Connect a vacuum pump to the Vacuum Pressure Sensor. |
| 4. | Apply vacuum to the Vacuum Pressure Sensor and watch for signal change. |
Is the voltage signal changing on the scan tool as vacuum is being applied?
Yes
- Go To 11
No
- Replace the Power Brake Booster in accordance with the Service Information. (Refer to 05 - Brakes/Hydraulic/Mechanical/BOOSTER, Power Brake - Removal) .
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
11. CHECK BRAKE BOOSTER CHECK VALVE
| 1. | Remove the Brake Booster Check Valve. |
| 2. | Apply vacuum to the booster side of the check valve. |
Is the Brake Booster Check Valve holding vacuum?
Yes
- Go To 12
No
- Replace the Power Brake Booster Check Valve in accordance with the Service Information. (Refer to 05 - Brakes/Hydraulic/Mechanical/BOOSTER, Power Brake - Removal) .
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
| 1. | Reinstall the Brake Booster Check Valve. |
| 2. | Apply vacuum to the Brake Booster. |
Is the Brake Booster holding vacuum?
Yes
- Go To 13
No
- Replace the Power Brake Booster in accordance with the Service Information. (Refer to 05 - Brakes/Hydraulic/Mechanical/BOOSTER, Power Brake - Removal) .
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
13. ANTI-LOCK BRAKE SYSTEM (ABS)
| 1. | Turn the ignition off to the lock position. |
| 2. | Perform any Technical Service Bulletins that may apply. |
| 3. | Inspect the related wiring harness. Look for any chafed, pierced, pinched or partially broken wires. |
| 4. | Inspect the related wire harness connectors. Look for broken, bent, pushed out or corroded terminals. |
Were any problems found?
Yes
- Repair as necessary.
- Perform the POWERTRAIN VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Powertrain Control (PCM) - Standard Procedure).
No
- Replace the Anti-lock Brake System (ABS) Module in accordance with the Service Information.
- Perform the ABS VERIFICATION TEST. (Refer to 28 - DTC-Based Diagnostics/MODULE, Antilock Brake (ABS) - Standard Procedure).