Low Coolant Lamp Inoperative - Hummer H1 Service Manual

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LOW COOLANT LAMP INOPERATIVE

The coolant level sensor is a solid-state semi-conductor device.
The sensor's resistance varies as a function of its temperature.
As voltage/current flows through the sensor, sensor tempera-
ture increases. In the presence of a liquid, in this case engine
coolant, the temperature of the sensor is controlled by transfer-
ring heat to the coolant. Should the coolant level drop below
the sensor, the heat and resistance of the sensor will rise. The
"Low Coolant" warning light will then illuminate in response
to the increased resistance at the sensor.
Step
1 Disconnect connector C35 from low coolant sen-
sor pigtail. Turn ignition switch to ON. Check ter-
minal A (pink wire) for voltage. Is voltage
present?
2 Disconnect connector C35 from low coolant sen-
sor pigtail. Turn ignition switch to ON. Connect a
fused jumper from terminal A (pink wire) to ter-
minal B (red wire) of the harness side of connec-
tor C35.
Does the low coolant lamp light?
3 Check/repair circuit 57 (black wire) from sensor
to engine ground.
Does the low coolant lamp light?
05745159
Action
Electrical System
Value(s) Yes
Approximate Go to step 2.
battery voltage.
Go to step 3.
Repair complete.
12-69
No
Repair circuit
291 from fuse
3B in exterior
fuse box.
Check/repair
signal circuit
794 and lamp in
status center.
Repair connec-
tion at connec-
tor C35 or
replace sensor
4-1-00