"CHECK COOLANT LEVEL" Message

Circuit Description

This test checks for a low engine coolant condition. The pressurized coolant bottle is equipped with a level switch which opens when coolant level is low. The PCM monitors the state of this switch through CKT 1478 and measures the time that the switch is open. If the switch is open for longer than a calculated period of time, the PCM tells the IPC via the data link to turn on the 'CHECK COOLANT LEVEL' message.

The calculated period of time before a low coolant condition is based on vehicle speed and acceleration. The higher vehicle speed and acceleration, the longer the time before a low coolant condition will be recognized.

Test Condition(s)

1. Codes P024 and P075 not set.
2. Engine coolant temperature above 22°C.

Failure Condition(s)

1. Coolant level input high for between 2.1 and 26.3 seconds (based on vehicle speed and acceleration).

Action Taken

1. 'CHECK COOLANT LEVEL' message is displayed on the DIC for the entire ignition cycle.

Notes on Fault Tree

1. Physically checking if low coolant level is causing the message.
2. Checking for an open coolant level switch.
3. Checking CKT 1478 for an open or if the PCM is bad.