The Powertrain Control Module (PCM) has four fuel injector driver circuits, each of which controls a fuel injector. The PCM monitors the current in each driver circuit and is able to control the driver circuit. The current through each driver can rise to a peak of 2 amps in order to quickly open the fuel injectors. The current can reduce to 1/2 amp to hold the fuel injectors open. This is called peak and hold. If the current cannot reach a 2-amp peak, a DTC is set. This DTC is also set if a fuel injector driver is shorted to voltage.
• | The engine is running. |
• | The battery voltage is more than 9 volts. |
• | The injector current is less than 1 amp. |
Or |
The injector current is continuously high. |
• | The above conditions are met for 7 seconds. |
• | The malfunction indicator lamp (MIL) illuminates. |
• | The PCM records the operating conditions at the time when the diagnostic fails. This information stores in the Freeze Frame and Failure Records buffers. |
• | A history DTC stores. |
• | The coolant fan turns ON. |
• | The MIL will turn OFF after three consecutive ignition cycles in which the diagnostic runs without a fault. |
• | A history DTC will clear after 40 consecutive warm-up cycles without a fault. |
• | Use a scan tool to clear the DTCs. |
An injector driver circuit that is open or shorted to voltage will cause a DTC P0201-204 to set and will also cause a misfire due to an inoperative injector. A misfire DTC should also be set, indicating which injector is inoperative.
Long-term and short-term fuel trims that are excessively high or low are a good indication that an injector is malfunctioning. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) to check for malfunctioning injectors.
A faulty electrical connection may be cleaned when you are disconnecting and reconnecting the electrical connector. If the malfunction is not present after the electrical connector is disconnected and reconnected, check the electrical terminal connection for the following conditions:
• | Corrosion |
• | Faulty terminal tension |
The numbers below refer to the step numbers on the diagnostic table.
The Powertrain On-Board Diagnostic (OBD) System Check prompts you to complete some of the basic checks and to store the Freeze Frame and Failure Records data on the scan tool if applicable. This creates an electronic copy of the data that was captured when the malfunction occurred. The scan tool stores this data on the scan tool for later reference.
This step tests the harness wiring and for the PCM control of the fuel injectors by using the fuel injector test lamp. If the test lamp blinks, this indicates that the PCM and the wiring to the fuel injectors are OK.
Whether the test lamp was ON steady or OFF while cranking the engine, this step narrows the malfunction down to just a few possibilities.
Because the test lamp was ON steady, the voltage to the fuel injector is OK, but the fuel injector driver circuit is grounded at all times. This step determines if the circuitry is shorted to ground or if the PCM is malfunctioning.
This step determines if the voltage is available to the fuel injector. The voltage is supplied through the fuel pump relay so that the engine must be cranked in order for you to see voltage at the fuel injector.
This step determines if the fuel injector driver circuit is open or shorted to voltage or if the PCM is malfunctioning.
Because the voltage is supplied to the fuel injector on a single circuit before the fuel injector harness, the malfunction could only be a faulty electrical connection or an open in the fuel injector harness. An open before the harness would result in a Cranks But Will Not Run complaint.
Check for faulty electrical connections and corroded terminals at the following connectors:
• | The fuel injector electrical connector |
• | The fuel injector harness connector |
Reprogram the replacement PCM and perform the crankshaft position system variation learn procedure. Refer to the latest Techline™ information for PCM programming.
Step | Action | Value(s) | Yes | No | ||||
---|---|---|---|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | |||||||
2 | Attempt to start the engine. Will the engine start? | -- | ||||||
Does the fuel injector test lamp blink on all of the tests? | -- | |||||||
Was the fuel injector test lamp ON steady in step 3 for the affected fuel injector electrical connector that did not blink? | -- | |||||||
Notice: Do not insert test equipment probes (DVOM etc.) into any connector or fuse block terminal. The diameter of the test probes will deform most terminals. A deformed terminal will cause a poor connection, which will result in a system failure. Always use the J-35616 GM-Approved Terminal Test Kit in order to front probe terminals. Do not use paper clips or other substitutes to probe terminals. When using the J-35616 GM-Approved Terminal Test Kit, ensure the terminal test adapter choice is the correct size for the connector terminal. Do not visually choose the terminal test adapter because some connector terminal cavities may appear larger than the actual terminal in the cavity. Using a larger terminal test adapter will damage the terminal. Refer to the J-35616 GM-Approved Terminal Test Kit label on the inside of the J-35616 GM-Approved Terminal Test Kit for the correct adapter along with the connector end view for terminal size.Does the test lamp illuminate? | -- | |||||||
6 | Repair the short to ground in the driver circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | -- | |||||
Notice: Do not insert test equipment probes (DVOM etc.) into any connector or fuse block terminal. The diameter of the test probes will deform most terminals. A deformed terminal will cause a poor connection, which will result in a system failure. Always use the J-35616 GM-Approved Terminal Test Kit in order to front probe terminals. Do not use paper clips or other substitutes to probe terminals. When using the J-35616 GM-Approved Terminal Test Kit, ensure the terminal test adapter choice is the correct size for the connector terminal. Do not visually choose the terminal test adapter because some connector terminal cavities may appear larger than the actual terminal in the cavity. Using a larger terminal test adapter will damage the terminal. Refer to the J-35616 GM-Approved Terminal Test Kit label on the inside of the J-35616 GM-Approved Terminal Test Kit for the correct adapter along with the connector end view for terminal size.Does the test lamp illuminate while cranking? | -- | |||||||
Notice: Do not insert test equipment probes (DVOM etc.) into any connector or fuse block terminal. The diameter of the test probes will deform most terminals. A deformed terminal will cause a poor connection, which will result in a system failure. Always use the J-35616 GM-Approved Terminal Test Kit in order to front probe terminals. Do not use paper clips or other substitutes to probe terminals. When using the J-35616 GM-Approved Terminal Test Kit, ensure the terminal test adapter choice is the correct size for the connector terminal. Do not visually choose the terminal test adapter because some connector terminal cavities may appear larger than the actual terminal in the cavity. Using a larger terminal test adapter will damage the terminal. Refer to the J-35616 GM-Approved Terminal Test Kit label on the inside of the J-35616 GM-Approved Terminal Test Kit for the correct adapter along with the connector end view for terminal size.Is the test lamp OFF while you crank the engine? | -- | |||||||
Is the action complete? | -- | -- | ||||||
Is a problem present? | -- | |||||||
11 |
Is the action complete? | -- | -- | |||||
12 | Repair the following conditions in the fuel injector driver circuit: Refer to Wiring Repairs in Wiring Systems.
Is the action complete? | -- | -- | |||||
Important: Refer to Powertrain Control Module Replacement/Programming . Replace the PCM. Refer to Powertrain Control Module Replacement . Did you complete the replacement? | -- | -- | ||||||
14 |
Does the scan tool indicate that this diagnostic has ran and passed? | -- | ||||||
15 | Check to see if any additional DTCs are set. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to applicable DTC | System OK |