When the ignition switch is placed in the START position, a discrete signal is supplied to the steering column control module (SCCM) notifying it that the ignition is in the START position. The SCCM then sends a serial data message to engine control module (ECM) and the underhood electrical center (UEC), that CRANK has been requested. The UEC then supplies 12  volts to the coil side of the STARTER relay, when the ignition is in the start position. The ECM then supplies a ground to the control circuit of the starter relay. When this occurs, battery voltage is supplied through the switch of the starter relay through the closed PNP switch to the starter solenoid. On manual transmissions the clutch start switch interrupts the control circuit from the ECM to prevent the engine from cranking unless the clutch pedal is fully pressed.

The UEC detects improper voltage on the control circuit of the starter relay.

DTC B1428 sets as current in the UEC

The DTC clears when the relay B+ or relay control circuit has repaired or a faulty starter relay has been replaced.

Schematic Reference

Starting and Charging Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Starting System Description and Operation

Electrical Information Reference

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, verify that no power mode , clutch pedal, automatic transmission, serial data, or related UEC, SCCM , ECM DTCs are set.

⇒	If other DTCs are set diagnosis those first.

1. Verify that DTCs P0616 or P0617 are not set
2. Ignition ON, verify DTC B1428 is set as current.
3. Ignition OFF, disconnect the starter relay, test for 60-180  ohms between relay terminals 85 and 86.

⇒	If not within the specified range, replace the starter relay.

4. Ignition ON, verify a test lamp illuminates between the relay coil supply voltage circuit terminal 86 and ground.

⇒	If the test lamp did not illuminate , test the relay coil supply voltage circuit for a short to ground or an open/high resistance.

5. Ignition OFF, connect a test lamp between the relay coil supply voltage circuit terminal 86 and the relay control circuit terminal  85.
6. Fully depress clutch pedal on manual transmissions or PARK/Neutral on automatic transmissions.
7. Place the ignition to the start position.
8. The test lamp should only illuminate when the ignition is held in the start position.

⇒	If the test lamp is always ON, test the control circuit for short to ground.

⇒	If the test lamp is always OFF, test the control circuit for a short to voltage or an open/ high resistance.

9. If the circuits test normal, replace the ECM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.