Use this procedure to troubleshoot any suspect problems with the injection actuation pressure sensor (IAPS) .
This procedure covers the following diagnostic code:
- 164-02 Injector Actuation Pressure signal erratic
Note: This procedure can check the accuracy of the injection actuation pressure sensor against a pressure gauge.
The IAPS measures the pressure of the oil in the high pressure oil manifold. The high pressure oil in the manifold is used to actuate the injectors and the high pressure oil is used to control the fuel injection pressure. The ECM uses the reading from the IAPS in order to control the operation of the injection actuation pressure control valve.
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| Illustration 1 | g01095091 |
Schematic for the injection actuation pressure sensor | |
Test Step 1. Check for Active Diagnostic Codes
- Connect the Caterpillar Electronic Technician (ET) to the service tool connector. Refer to Troubleshooting, "Electronic Service Tools".
- Turn the keyswitch to the ON position.
- Observe the "Active Diagnostic" screen on Cat ET. Wait at least 15 seconds so that any codes may become active. Look for an active 164-02 diagnostic code.
Note: If one of the following diagnostic codes are active refer to Troubleshooting, "Engine Pressure Sensor Open or Short Circuit - Test":
- 164-03 Injector Actuation Pressure voltage high
- 164-04 Injector Actuation Pressure voltage low
- 164-03 Injector Actuation Pressure voltage high
Expected Result:
The 164-02 diagnostic code is active.
Results:
- Active code - The 164-02 diagnostic code is active. Proceed to Test Step 3.
- No active code - The 164-02 diagnostic code is not active. Proceed to Test Step 2.
Test Step 2. Try to Start the Engine
Try to start the engine.
Expected Result:
The engine starts.
Results:
- OK - The engine starts. There are no active codes for the IAPS and the engine starts.
Repair: There may be an intermittent problem in a harness that is causing the code to be logged. Refer to Troubleshooting, "Electrical Inspectors - Inspect".
STOP
- Not OK - The engine does not start.
Repair: Refer to Troubleshooting, "Engine Cranks but Will Not Start".
STOP
Test Step 3. Inspect the Electrical Connectors and the Wiring
- Turn the keyswitch to the OFF position.
- Thoroughly inspect connectors (1) and (2). Refer to Troubleshooting, "Electrical Connectors - Inspect".
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| Illustration 2 | g01192981 |
Typical left side view (1) J500/P500 connectors for the injection actuation pressure sensor (2) J2/P2 connectors | |
- Perform a 45 N (10 lb) pull test on each of the wires that are associated with the IAPS.
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| Illustration 3 | g01094031 |
P2 terminals that are associated with the injection actuation pressure sensor (P2-3) Return (P2-2) +5 VDC (P2-25) Injection Actuation pressure | |
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| Illustration 4 | g01123211 |
Connectors for the injection actuation pressure sensor (A) Supply (B) Return (C) Signal | |
- Check the torque of the allen head screws for the ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
- Check the harness and wiring for abrasion and for pinch points from the sensor back to the ECM.
Expected Result:
All connectors, pins, and sockets are completely coupled and/or inserted. The harness and wiring are free of corrosion, of abrasion, and of pinch points.
Results:
- OK - The connectors and wiring are OK. Proceed to Test Step 4.
- Not OK - There is a problem in the wiring and/or a connector.
Repair: Repair the wiring and/or the connector. Replace parts, if necessary. Ensure that all of the seals are properly in place and ensure that the connectors are completely coupled.Verify that the problem is resolved.
STOP
Test Step 4. Check the Status of the Sensor
- Turn the key switch to the ON position.
- Check the value of the "Injection Actuation Pressure" on Cat ET.
Note: The following codes will cause the value of the "Injection Actuation Pressure" to default to 17500 kPa (2538 psi).
- 164-03 Injector Actuation Pressure voltage high
- 164-04 Injector Actuation Pressure voltage low
- 164-03 Injector Actuation Pressure voltage high
Expected Result:
The value of the "Injection Actuation Pressure" is 0 kPa (0 psi).
Results:
- OK - The value of the "Injection Actuation Pressure" is 0 kPa (0 psi). Proceed to Test Step 6.
- Not OK - The value of the "Injection Actuation Pressure" is above 0 kPa (0 psi). Proceed to Test Step 5.
Test Step 5. Check the Voltage Supply to the Injection Actuation Pressure Sensor
- Turn the keyswitch to the OFF position.
- Disconnect the IAPS connector.
- Connect a 3-terminal breakout T to the harness side of the IAPS connector.
- Turn the keyswitch to the ON position.
- Measure the voltage between terminals A and B at the breakout T.
Expected Result:
The voltage reading is 5 ± 0.2 VDC.
Results:
- OK - The voltage is within the specified range. Proceed to Test Step 6.
- Not OK - The voltage is not within the specified range.
Repair: Refer to Troubleshooting, "Analog Sensor Supply Circuit - Test".
STOP
Test Step 6. Compare the Sensor's Output to a Pressure Gauge
- Turn the keyswitch to the OFF position.
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Hot oil and hot components can cause personal injury. Do not allow hot oil or hot components to contact the skin. |
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- Install a 8T-0852 Pressure Gauge to an oil port on the side of the cylinder head or to the port on the top of the fuel transfer pump.
- Start the engine.
- Go to the "Injection Actuation Pressure Test" on the diagnostic menu of Cat ET.
- Start the "Injection Actuation Pressure Test".
- Refer to Table 1. Observe the value of the "Injection Actuation Pressure" on Cat ET. Vary the engine speed in order to obtain each "Injection Actuation Pressure" value that is listed in the Table. For each pressure value, observe the reading on the pressure gauge.
Show/hide table
Table 1 Comparison of Pressure Readings "Injection Actuation Pressure" Values on Cat ET Range of Acceptable Pressure Values on the Pressure Gauge 6000 kPa (870 psi) 4000-7800 kPa (580-1130 psi) 10000 kPa (1450 psi) 8000-11800 kPa (1160-1710 psi) 15000 kPa (2175 psi) 13000-16800 kPa (1885-2435 psi) 23000 kPa (3336 psi) 21000-24800 kPa (3045-3595 psi)
Expected Result:
Each value on the pressure gauge is within the specification.
Results:
- OK - Each value on the pressure gauge is within the specification. The IAPS and the ECM are working properly.
Repair: The problem appears to be resolved. The original diagnostic code was probably caused by an intermittent problem in an electrical connector. If the code continues to be logged, refer to Troubleshooting, "Electrical Connectors - Inspect".
STOP
- Not OK - At least one of the values on the pressure gauge is not within the specification.
Repair: Install a new IAPS and repeat the test.If the new sensor corrects the problem, leave the new sensor in place.If the new sensor does not correct the problem, the pressure gauge is faulty. Obtain a new pressure gauge and repeat the test.
STOP