The powertrain control module (PCM) enables an injector on the intake stroke of each cylinder. Individual cylinder fuel control is referred to as sequential multi-port fuel injection (SFI).
Ignition voltage is supplied directly to the fuel injectors. The PCM controls each injector by grounding the control circuit via an internal switch called a driver. The primary function of the driver is to supply the ground for the component being controlled. Each driver or control circuit is equipped with a fault line which is monitored by the PCM. When the PCM is commanding an injector ON, the voltage of the control circuit should be low. When the PCM is commanding the injector OFF, the voltage potential of the control circuit should be high. If the PCM detects the injector control circuit voltage other than what is expected, the PCM sets a diagnostic trouble code (DTC).
• | The engine speed is more than 400 RPM. |
• | The ignition voltage is more than 6.0 volts but less than 18.0 volts. |
The PCM detects the wrong voltage potential on any injector driver circuit for 5.0 seconds.
• | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails. |
• | The malfunction indicator lamp (MIL) will not illuminate. |
• | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records. |
• | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
• | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
• | Use a scan tool in order to clear the DTC. |
Important:
• Remove any debris from the PCM connector surfaces before servicing
the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the
PCM. Ensure that the gaskets are installed correctly. The gaskets prevent
contaminant intrusion into the PCM. • For any test that requires probing the PCM or component
harness connectors, use the J 35616
connector test adapter kit. Using this kit
prevents any damage to the harness connector terminals. Refer
to
Using Connector Test Adapters
in Wiring Systems for procedures.
• | A misfire may not be apparent at idle. The misfire may only occur above idle under a load. Road test the vehicle and monitor the misfire current counters. |
• | Observe, if more then one cylinder is mis-firing, the scan tool may only display one cylinder mis-firing. This will not be apparent until the repair is completed. Also, if an injector fuse is open, the scan tool may only display 2 or 3 cylinders mis-firing. |
• | When the injector driver is disabled, an engine misfire will be apparent and a misfire DTC sets. |
• | For an intermittent condition, refer to Symptoms . |
The numbers below refer to the step numbers on the diagnostic table.
This step determines if a malfunction is present.
The Misfire current counters will not increment if certain DTCs set at the same time or after DTC P0300 sets. Refer to the Conditions for Running in DTC P0300 for applicable DTC list.
If more than one cylinder is misfiring, the Misfire current counters may increment for only one cylinder. Example: Cylinders 1 and 8 are both misfiring, yet only cylinder 8 increments on the Misfire current counter.
There are two ways to isolate a malfunctioning injector circuit:
• | DTC P0300 indicates a misfire is present. Use the misfire current counters to locate the cylinder that is misfiring. |
• | If no misfire DTC is present, start and idle the engine while monitoring misfire current counters. If a misfire is present, the misfire current counters will increase for a cylinder that has a misfire. |
This step inspects for an open injector fuse which would cause DTC P0200 to set.
Inspect the injector connections before replacing the injector. A faulty connection causes an inoperative injector.
Disconnecting the PCM allows using the DMM to test continuity of the circuits. This aids in locating an open or shorted circuit. This step tests for an ignition feed circuit that is shorted to ground.
This step tests for an ignition feed circuit that is shorted to ground.
Step | Action | Values | Yes | No | ||||||
---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||||||||
Are any of the Misfire Current Counters incrementing? | -- | |||||||||
Monitor the Misfire History Counters on the Misfire Data List using a scan tool. There are a total of 8 counters. One counter per cylinder. Do any of the Misfire History Counters indicate a number other than 0.0 counts? | -- | Go to Diagnostic Aids | ||||||||
Is the injector fuse OK? | -- | |||||||||
5 |
Does the test lamp illuminate? | -- | ||||||||
6 |
Does the test lamp blink? | -- | ||||||||
Did you find and correct the condition? | -- | |||||||||
8 |
Does the test lamp illuminate? | -- | ||||||||
9 |
Important: Return to this diagnostic after performing the Fuel Injector Coil Test. Perform the Fuel Injector Coil Test. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) . Did any of the fuel injectors require replacement? | -- | ||||||||
10 | Repair the injector ignition feed circuit to the isolated injector. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||
Important: Disconnecting the PCM may eliminate the short to ground or short to voltage, if the circuit is shorted to another C1 circuit.
Is the injector driver circuit open, shorted to ground, or shorted to a voltage? | -- | |||||||||
12 | Repair the injector driver circuit for an open, short to ground, or a short to voltage. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||
Is the action complete? | -- | -- | ||||||||
14 | Repair intermittent short to ground in the injector ignition feed circuit. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||||
15 | Replace the faulty injectors that were isolated. Refer to Fuel Injector Replacement . Is the action complete? | -- | -- | |||||||
16 |
Did you find and correct the condition? | -- | ||||||||
17 |
Important:: The replacement PCM must be programmed. Replace the PCM. Refer to Powertrain Control Module Replacement/Programming . Is the action complete? | -- | -- | |||||||
18 |
Did you find and correct the condition? | -- | Go to Symptoms | |||||||
19 |
Does the scan tool indicate that this test ran and passed? | -- | ||||||||
20 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK |