Code 33

INJECTOR DRIVE CIRCUIT - DTC 33

The ECM looks for a low electrical load on the fuel injector drive circuit when the injectors are switched ON.

The fuel injectors are supplied with 12 volts and are triggered on the ground side by the ECM. To reduce power consumption, the current drawn by the injectors is controlled by the ECM. The injectors are opened by a relatively large "turn on" electrical pulse and are held open for the required pulse duration by a series of smaller "hold on" pulses. All six injectors are connected in parallel and operate simultaneously.

Injector Wave Form:

The ECM will flag DTC 33 if the fuel injector drive circuit voltage is 1.2 volts or greater when the injectors are ON.

Conditions Required For DTC 33 Flagging
Injector drive ON - 1.2 volts or greater.
Response time - 600 milliseconds.

Limp Home Default
None

Possible Faults
- Poor connection at the fuel injectors or the ECM.
- Open circuit or short circuit in injector harness.
- Poor power ground connection to the ECM (blue pins 11 and 23).
- Defective (open circuit) fuel injector(s).

Diagnostic Notes
1. The two injector supply pins on the ECM, blue 12 and 17, are connected together with pins 10 and 22 to supply 12 volts to the injectors.
2. The two injector drive pins on the ECM, blue 13 and 25, are connected together to provide the pulsed ground.
3. If one or two injectors are not operating, the fault is likely to be located in the fuel rail area of the harness.
4. The individual injector coil resistance is 2.2-3 ohms.

Circuit Diagram

Circuit Diagram:

Circuit Diagram:

Flow Chart - DTC 33

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Flow Chart - DTC 33: