Riviera V6-231 3.8L VIN C SFI (1989)
Body Control Module: Initial Inspection and Diagnostic Overview
Engine Overheat - "Hot" Lamp
Coolant Sensor Circuit
DESCRIPTION:
The ECM provides and internally monitors voltage to the
coolant temperature sensor circuit through pin C10. As the coolant temperature goes from cold to hot, the sensor's resistance goes from high to low, and
the voltage level the ECM detects at pin C10 goes from high to low. Every 1.0 second, the BCM checks the ECM for the coolant temperature. If the
calculated coolant temperature reaches 126°C (i.e. the voltage at pin C10 of the ECM drops low enough), and all other failure conditions are met, the
BCM will cause the coolant temperature gauge bars to flash, activate the fast chime on the chime module, illuminate the "HOT" lamp and display the
"ENGINE OVERHEAT" message on the CRT.
TEST CONDITIONS:
1.
Engine is running.
2.
Coolant temperature not failed.
3.
A/C clutch disengaged.
FAILURE CONDITIONS:
1.
Engine coolant temperature greater than 126°C.
2.
Engine overheat condition already present.
3.
Engine coolant temperature greater than 120°C.
ACTION TAKEN:
1.
Flash the IPC coolant temperature gauge bars.
2.
Activate the fast chime.
3.
Illuminate the "HOT" telltale on the IPC.
4.
Display "ENGINE OVERHEATED" message on the CRT.
