Riviera V6-231 3.8L VIN L SFI (1991)
Body Control Module: Initial Inspection and Diagnostic Overview
"Hot" Coolant Light
CTS Circuit
DESCRIPTION:
The PCM supplies and internally monitors voltage to the coolant temperature sensor circuit through pin 2A9. As the coolant temperature goes from cold
to hot, the sensor's resistance goes from high to low, and the voltage level the PCM detects at pin 2A9 goes from high to low. Every 1.0 second the BCM
checks the PCM for the coolant temperature. If the calculated coolant temperature reaches 126°C (i.e. the voltage at pin 2A9 of the PCM drops low
enough), and all other failure conditions have been met, the BCM will cause the "HOT" coolant light on the IPC to come "ON."
TEST CONDITIONS:
1.
Engine is running.
2.
Coolant temperature not failed.
3.
No data line codes set.
FAILURE CONDITIONS:
1.
Engine coolant temperature greater than 120°C.
2.
Engine overheat condition already present.
OR
3.
Coolant temperature is greater than 126°C.
ACTION TAKEN:
1.
Illuminate "HOT" telltale on IPC.
DIAGNOSIS:
Erroneous Message - Short to ground on circuit 410 or shorted switch.
No Message - Open in circuit 410 or open in switch.
