Cooling System Diagnosis - GMC G Service Manual

6B1-4 ENGINE COOLING
• If the lamp does not illuminate, check the bulb,
socket and wiring between the socket and the
module connector, as well as the connector on
the module. Replace or repair as required.
2. Turn the ignition switch to the "ON" position and dis­
connect the electrical lead at the coolant level sensor
on the radiator.
• If the lamp fails to illuminate, check the wiring
between the coolant level sensor connector and
the module for a short circuit to ground. If the
circuit is OK, replace the module.
INDICATOR LAMP REMAINS ILLUMINATED
1. Turn the ignition switch to ON.
• Check the coolant level. Add coolant if
necessary.
• If the lamp remains illuminated, go to Step 2.
2. Disconnect the electrical lead at the coolant level sen­
sor on the radiator (use a jumper wire and "G" type
electrical connector).
• If the lamp does not illuminate, replace the
sensor.
• If the lamp remains illuminated, connect the
electrical lead and go to Step 3.
3. Check for an open circuit between the sensor and the
module.
• If an open circuit is found, repair it.
• If no open circuit is found, replace the module.
A. Coolant Level Probe
B. Module
C. "Low Coolant" Indicator Lamp
D. Fuse
Figure 2 — Low Coolant Level Sensor Circuit

COOLING SYSTEM DIAGNOSIS

Refer to the cooling system diagnosis chart for detailed
cooling system diagnostic procedures (figures 3 and 4).
L00700