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FAULT CODE 331

Injector Solenoid Driver Cylinder 2 Circuit - Current Below Normal, or Open Circuit

Overview

CODE	REASON	EFFECT
Fault Code: 331	Injector Solenoid Driver Cylinder 2 Circuit - Current Below Normal, or Open Circuit. High resistance	Engine can misfire or
PID:	detected on injector number 2 circuit or no current detected at number 2 injector driver or return pin	possibly operate
SPN: 652	when the voltage supply at the harness is on.	rough.
FMI: 5
LAMP: Amber
SRT:

Injector Solenoid Driver Cylinder 2 Circuit

Circuit Description

The injector solenoid valves control fueling quantity and injection timing. The engine control module (ECM) energizes the solenoid by closing a high-side and a low-side switch. There are two high-side switches and six low-side switches inside the ECM. The injectors for cylinders 1, 2, and 3 (front bank) share a single high-side switch that connects the injector circuit to the source of high voltage inside the ECM. Likewise, the injectors for cylinders 4, 5, and 6 (rear bank) also share a single high-side switch. Each injector circuit has a dedicated low-side switch that completes the circuit path to ground inside the ECM.

Component Location

The engine harness connects the ECM to each injector. The injector connectors are located on the injector, above the rocker cover.

Shop Talk

Fault activation: The ECM senses current as each injector is actuated. If the ECM detects a persistent circuit error on an injector circuit, this fault will become active. If a circuit error is determined to cause excessive current, the ECM will disable the injection event for the cylinder(s) that is faulty.
Fault deactivation: The ECM will attempt to enable any disabled injector circuit whenever the engine is started and approximately once per minute while the engine is operating. If an injector circuit fault is active and the faulty condition is repaired, the fault will become inactive once the engine is restarted or if the engine is permitted to idle for more than 1 minute.
If a fault condition is intermittent and especially if more than one injector fault code is in the ECM memory, look for a wire harness that can short to components inside the rocker housing or for a short circuit to ground in the injector solenoid.
If more than one injector fault code is occurring and the faults occur for injector circuits in the same bank, a short circuit exists.

Causes of a single injector fault are:
Open circuit in the engine harness(es) or injector solenoid
High resistance in a single injector or injector solenoid
Extremely low resistance in an injector solenoid (injector shorted internally but not to ground)
Damaged ECM.

Causes of multiple injector fault codes in the same bank of injectors are:
Short circuit in the engine harness(es) - either shorts to ground or to other wires in the engine harness
Short circuit in any of the three injectors in the bank - shorts to ground
Damaged ECM.