Low Engine Coolant Indicator Always On

/ 9-5 (9650) / 2010 / 2. Engine / Cooling system / Fault diagnosis, fault symptoms / Low Engine Coolant Indicator Always On

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.

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage	Signal Performance
Coolant Level Switch Signal	Lamp ON	Lamp OFF	Lamp OFF	-
Low Reference	-	Lamp OFF	-	-

Circuit/System Description

The low engine coolant level indicator lamp is located in, and controlled by the instrument panel cluster (IPC). The engine coolant level switch is located in the engine coolant surge tank. The switch remains open when surrounded by coolant. When the engine coolant level switch is closed for greater than 10 seconds, indicating low coolant, the IPC will turn ON the Low Coolant Indicator lamp. The lamp will also illuminate for approximately 3 seconds during the display test at the start of each ignition cycle.

Reference Information

Schematic Reference

Engine Cooling Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cooling System Description and Operation

Electrical Information Reference

•	Circuit Testing

•	Connector Repairs

•	Testing for Intermittent Conditions and Poor Connections

•	Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1.	Ignition OFF, verify the radiator surge tank is filled to the correct level, with engine coolant.

2.	Ignition ON, observe the scan tool Coolant Level Switch parameter. The parameter should display OK.

3.	Command the instrument cluster indicators ON and OFF with a scan tool. The low coolant indicator lamp should turn ON and OFF as commanded. Refer to Cooling System Description and Operation .

4.	The low coolant indicator should be OFF with the engine coolant at the correct level.

Circuit/System Testing

Note

Circuit/System Verification must be performed before performing the Circuit/System Testing.

1.	Ignition OFF, disconnect the harness connector at the B33 coolant level switch.

2.	Test for less than 5Ω between the ground circuit terminal 1 and ground.

3.	If greater than the specified range, test the ground circuit for an open/high resistance.

4.	Ignition ON, observe the scan tool Coolant Level Switch parameter. The parameter should display OK.

5.	If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the P16 IPC.

6.	Install a 3 A fused jumper wire between the signal circuit terminal 2 and the ground circuit terminal 1. Verify the scan tool Coolant Level Switch parameter displays Low, and the low coolant lamp in the IPC is ON.

7.	If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the P16 IPC.

8.	If all circuits test normal, test or replace the B33 coolant level switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

•	Engine Coolant Level Indicator Module Replacement

•	Control Module References for ECM replacement, setup, and programming

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