DTC P0091 Without RPO CTF
Circuit Description
The pressure control (PC) valve is used to adjust supply pump discharge amount so as to adjust common rail pressure. Discharge amount from the supply pump to the common rail is determined by PC valve current timing.
Conditions for Setting the DTC
Abnormally low driving voltage with PC valve OFF, pump normal mode, battery voltage higher than 10 volts and no crankshaft position (CKP) sensor faults with the ignition ON.
Action Taken When the DTC Sets
| • | The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. |
| • | The ECM limits fuel delivery. |
Conditions for Clearing the MIL/DTC
| • | The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. |
| • | Clear the MIL and the DTC with a scan tool. |
Diagnostic Aids
Inspect for the following conditions:
| • | Poor connections at the ECM |
| Inspect the harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection. |
| • | Damaged harness |
| Inspect the wiring harness for damage, shorts to ground, shorts to battery, and open circuits. If the harness appears to be OK, observe the PC valve display on the scan tool while moving connectors and wiring harnesses related to the PC valve sensor. A change in the PC valve sensor scan tool display will indicate the location of the fault. |
Step | Action | Value | Yes | No |
|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||
1 | Does the DTC set with the engine is running? | -- | Go to Step 2 | Go to Diagnostic Aids |
2 |
Does the voltage measure within the specified range? | 10-14 V | Go to Step 8 | Go to Step 3 |
3 |
Important : If DTC P1298 is also present, test for voltage before measuring the resistance.
Does the resistance measure more than the specified value? | 10 M ohms | Go to Step 5 | Go to Step 4 |
4 |
Does the resistance measure less than the specified value? | 10 ohms | Go to Step 15 | Go to Step 5 |
5 | Measure the resistance on the PC valve harness between pin number C5-1 at the ECM and PC valve 1 and pin number 2. Does each resistance measure less than the specified value? | 0.5 ohms | Go to Step 6 | Go to Step 14 |
6 | Measure the resistance from pin number 1 at the PC valve relay and pin number 2 at the PC valve relay. Does the resistance measure more than the specified value? | 10 M ohms | Go to Step 7 | Go to Step 15 |
7 | Measure resistance between pin number 1 at the PC valve 1 connector and pin number 1 at the PC valve relay. Does the resistance measure less than the specified value? | 2 ohms | Go to Step 8 | Go to Step 10 |
8 | Measure the PC valve coil resistance. Does the resistance measure within the specified range? | 0.9-1.3 ohms | Go to Step 9 | Go to Step 11 |
9 |
Does the voltage measure within the specified range? | 10-14 V | Go to Step 13 | Go to Step 12 |
10 | Repair/replace the PC valve harness. Did you complete the action? | -- | Go to Step 17 | -- |
11 | Replace the PC valve. Did you complete the replacement? | -- | Go to Step 17 | -- |
12 | Repair the wiring harness in between the power supply and the PC valve relay. Did you complete the repair? | -- | Go to Step 17 | -- |
13 | Repair the poor connection at the PC valve harness connector. Did you complete the repair? | -- | Go to Step 17 | Go to Step 16 |
14 | Repair or replace the wiring harness between the ECM and the PC valve. Did you complete the action? | -- | Go to Step 17 | -- |
15 | Repair or replace the wiring harness between the PC valve and the PC valve relay. Did you complete the action? | -- | Go to Step 17 | -- |
16 | Replace the ECM. Did you complete the replacement? | -- | Go to Step 17 | -- |
17 | Clear all DTCs. Does the DTC reset? | -- | Go to Step 1 | Go to Step 18 |
18 | Operate the vehicle. Do any other DTCs set? | -- | System OK | |
DTC P0091 With RPO CTF
Circuit Description
The suction control valve (SCV) is on the fuel supply pump and controls the suction fuel quantity to the fuel rail. The SCV is fully opened in normal state and increased drive current results in closing the orifice. The engine control module (ECM) calculates desired fuel rail pressure and fuel flow rate, and compares the desired fuel rail pressure to the actual rail pressure to determine the SCV position. When the actual fuel rail pressure is higher than the desired value, the SCV is closed to decrease the flow rate. If the ECM detects an excessively low SCV solenoid drive current, this DTC will set.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | The battery voltage is between 10-16 volts. |
| • | The fuel supply pump is normal. |
| • | The SCV operating duty is between 20-50 percent. |
| • | The deviation of the SCV cycle duty is less than 10 percent. |
Conditions for Setting the DTC
The SCV solenoid operating current is less than 400 mA.
Action Taken When the DTC Sets
| • | The ECM illuminates the malfunction indicator lamp (MIL) and reduced engine power indicator lamp, if equipped, when the diagnostic runs and fails. |
| • | The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records. |
| • | The ECM limits accelerator operating range. |
| • | The ECM limits fuel injection quantity. |
| • | The ECM limits fuel rail pressure. |
| • | The ECM closes the exhaust gas recirculation (EGR) valve and holds to the closed position. |
| • | The ECM inhibits cruise control. |
| • | The ECM inhibits PTO control. |
Conditions for Clearing the DTC
| • | The MIL resets when the ignition is turned OFF. |
| • | A current DTC, Last Test Failed, clears when the diagnostic runs and passes. |
| • | Clear the MIL and the DTC with a scan tool. |
Step | Action | Values | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
Schematic Reference: Engine Controls Schematics | ||||||||||
1 | Did you perform the Diagnostic System Check - Engine Controls? | -- | Go to Step 2 | |||||||
2 |
Does the DTC fail this ignition? | -- | Go to Step 3 | Go to Intermittent Conditions | ||||||
3 |
Did you find and correct the condition? | -- | Go to Step 11 | Go to Step 4 | ||||||
4 |
Is the resistance within the specified range? | 1.9-2.3 ohms at 20°C (68°F) | Go to Step 5 | Go to Step 8 | ||||||
5 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 6 | ||||||
6 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 7 | ||||||
7 |
Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 | ||||||
8 |
Important: The SCV is part of the fuel supply pump. Replace the fuel supply pump. Refer to Fuel Injection Pump Replacement . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||
9 |
Important: The new ECM must be programmed. Replace the ECM. Refer to Engine Control Module Replacement/Restore Fuel Rate Data . Did you complete the replacement? | -- | Go to Step 10 | -- | ||||||
10 |
Did the DTC fail this ignition? | -- | Go to Step 2 | Go to Step 11 | ||||||
11 | Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed? | -- | System OK | |||||||
