P0201

DTC P0201 Injector 1 Circuit Fault

Circuit Diagram:

Circuit Description
The Engine Control Module (ECM) has four individual injector driver circuits, each of which controls an injector. When a driver circuit is grounded by the ECM, the injector is activated. The ECM monitors the current in each driver circuit. The ECM measures a voltage drop through a fixed resistor and controls it. The voltage on each driver is monitored to detect a fault. If the voltage is not what the ECM expects to monitor on the circuit, a Diagnostic Trouble Code (DTC) is set. This DTC detects a short to ground and/or an open circuit and short to battery conditions for low-side drive injector outputs.

Conditions for Setting the DTC
- Monitor fault feedback signal from FETS.
- Engine is in run mode.
- Battery voltage is greater than 9 volts.
- Engine speed is greater than 700 rpm.
- Fault is present for more than 5 seconds.

Action Taken When the DTC Sets
- The ECM will illuminate the Malfunction Indicator Lamp (MIL) the first time the fault is Detected.
- The ECM will store conditions which were present when the DTC was set as Freeze Frame and in the Failure Records data.

Conditions for Clearing the MIL/DTC
- The ECM will turn off the MIL on the third consecutive trip cycle in which the diagnostic has been run and the fault is no longer present.
- A history will clear after 40 consecutive warm-up cycles without a fault.
- DTC can be cleared by using the scan tool Clear Info function.
- Disconnecting the ECM battery feed for more than 10 seconds.

Diagnostic Aids
An injector 1 driver circuit that is open or shorted to voltage will cause a DTC P0201 to set. It 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 trim's that are excessively high or low are a good indication that an injector is malfunctioning. Refer to Fuel Injector Balance Test to check for malfunctioning injectors.

The injector resistance tested at the ECM connection is slightly more than if tested directly at the injector because it includes resistance of the harness wires. The normal value is about 13.5 Ohm

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
1. The On-Board Diagnostic (OBD II) System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored on the scan tool for later reference.
3. This step determines if DTC P0201 is the result of a hard failure or an intermittent condition.
5. This step tests the wiring harness and the ECM control of the injectors using a test light.
7. This step determines if the circuitry is shorted to voltage or the ECM is faulty.
9. The replacement ECM must be reprogrammed. Refer to the latest Techline procedure for ECM reprogramming.

Step 1 - 3:

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