• | 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
---|---|---|---|---|
Relay Coil B+ Terminal 85 | 1 | 1 | -- | -- |
Relay Switch B+ Terminal 30 | 1 | 1 | -- | -- |
ECM Park Neutral Signal | 2 | 1 | -- | -- |
Relay Coil Control Terminal 86 | 3 | 1 | 1 | -- |
Relay Control Output Terminal 87 | 1 | 1 | 3 | -- |
1. No crank 2. Cranks in any gear 3. Cranks all the time |
When the ignition mode switch is placed in the START position, a discrete signal is supplied to the body control module (BCM) notifying it that the ignition is in the START position. The BCM then sends a message to the engine control module (ECM) that crank has been requested. The ECM then verifies that the transmission is in Park or Neutral. If it is, the ECM then supplies a ground to the control circuit of the CRANK relay. When this occurs, battery voltage is supplied through the switch of the CRANK relay to the starter solenoid.
Starting System Description and Operation
Control Module References for scan tool information
⇒ | If DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. |
⇒ | If not the specified value, refer to Power Mode Description and Operation. |
⇒ | If the TCM IMS parameter does not indicate Park/Neutral, refer to Transmission Internal Mode Switch Logic. |
⇒ | If the ECM Park/Neutral parameter does not indicate Park/Neutral, refer to ECM Park Switch Circuit Malfunction. |
⇒ | If the starter relay does not click or the engine does not crank, refer to Crank Relay Circuit Malfunction. |
⇒ | If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
⇒ | If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the ECM. |
⇒ | If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the ECM. |
⇒ | If the solenoid does not engage, test the control output circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the starter motor. |
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
• | Control Module References for ECM replacement, setup and programming |