For 1990-2009 cars

## Fuel Injector Solenoid Coil Test w/LLT

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### Circuit/System Description

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. The ECM supplies a high voltage control circuit and a low control circuit to each of the fuel injectors. The control module controls each fuel injector control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect the engine driveability. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

### Diagnostic Aids

• | Monitoring the misfire current counters, or misfire graph, may help to isolate the fuel injector that is causing the condition.

• | If the condition is intermittent, move the related harnesses and connectors, with the engine operating, while monitoring the scan tool Fuel Injector Circuit Test Status parameter. The Fuel Injector Circuit Test Status parameter will change from OK or Not Run to Fault if there is a condition with the circuit or a connection.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

### Component Testing

Important:

• | The engine coolant must be within the specified range or mis-diagnosis will occur.

• | The resistance test must be performed at the fuel injector or mis-diagnosis will occur.

• | The DMM and test leads must be calibrated to 0 ohms in order to prevent mis-diagnosis.

1. Engine coolant between 10-32°C (50-90°F).
2. Test for 1.30-1.73 ohms between the terminals of the fuel injector. The resistance of each fuel injector should be 1.30-1.73 ohms.

⇒ | If not within the specified range, replace the fuel injector.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Injector Replacement

## Fuel Injector Solenoid Coil Test w/LY7

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category

### Circuit/System Description

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. The ignition voltage is supplied directly to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect the engine driveability. A fuel injector control circuit DTC may not set but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

### Diagnostic Aids

• | Monitoring the misfire current counters, or misfire graph, may help to isolate the fuel injector that is causing the condition

• | Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition

• | Perform the fuel injector coil test within the conditions of the customers concern. A fuel injector condition may only be apparent at a certain temperature or under certain conditions.

### Reference Information

#### Schematic Reference

Engine Controls Schematics

#### Connector End View Reference

Component Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

#### Scan Tool Reference

Control Module References for scan tool information

### Component Testing

Verify the resistance of each fuel injector with one of the following methods:

• | If the engine coolant temperature (ECT) sensor is between 10-32°C (50-90°F), the resistance of each fuel injector should be 11-14 Ω.

⇒ | If the resistance of any fuel injector is not 11-14 Ω, replace the fuel injector

• | If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each fuel injector with a DMM. Subtract the lowest resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3 Ω

⇒ | If the difference is equal to or less than 3 Ω, refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Balance Test with Tech 2

⇒ | If the difference is greater than 3 Ω, add all of the fuel injector resistance values to obtain a total resistance value. Divide the total resistance value by the number of fuel injectors to obtain an average resistance value. Subtract the lowest, and the highest, individual fuel injector resistance values from the average resistance value. Replace the fuel injector that displays the greatest resistance difference above or below the average.

### Repair Instructions

Perform the Diagnostic Repair Verification.

Fuel Injector and Fuel Rail Replacement.