• | 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 |
---|---|---|---|---|
Coolant Level Switch Signal | Lamp ON | Lamp OFF | -- | -- |
Ground | -- | Lamp OFF | -- | -- |
The low engine coolant level indicator lamp on the instrument panel cluster (IPC) is controlled by the body control module (BCM) through the low speed GM LAN Serial Data line to the engine control module (ECM). When the engine coolant level switch is closed for 30 seconds or longer indicating low coolant, the BCM will signal the ECM to turn ON the coolant level lamp. The lamp will also illuminate for approximately 3 seconds during the display test at the start of each ignition cycle.
Cooling System Description and Operation
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Control Module References for scan tool information
Important: Circuit/System Verification must be performed before performing the Circuit/System Testing.
⇒ | If the low coolant level indicator does NOT turn OFF, test for poor connections at the IPC or a faulty IPC. |
⇒ | If the low coolant level indicator turns OFF with the switch disconnected, replace the coolant level switch. |
⇒ | If the low coolant level indicator does not turn OFF with the switch disconnected, test the signal circuit of the coolant level switch for a short to ground. |
⇒ | If the signal circuit tests normal, inspect for poor connections at the BCM or a faulty BCM. |
• | Control Module References for ECM replacement, setup, and programming |
Verify that the low coolant indicator is OFF with the engine coolant at the proper level.