Engine Temperature Gauge Inoperative - Hummer H1 Service Manual

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Step
1 Is gauge maxed out with ignition on?
2 Using a DVOM set to measure voltage, check for
voltage at the rear of the oil pressure gauge on the
grey wire(CKT39) connect negative meter lead to
ground on black wire(CKT59). With ignition on,
is voltage present?
3 Move the negative meter lead to a known good
ground. Is voltage present?
4 With the ignition on, momentarily ground the
dark green wire(CKT30) at the rear of the gauge.
Does the gauge go to maximum?
5 With the ignition on, momentarily ground the sig-
nal wire(CKT39) at the sending unit. Does the
gauge go to maximum?
05745159

Engine Temperature Gauge Inoperative

Action
Electrical System
Value(s) Yes
Repair short to
ground in CKT
39 or faulty
sending unit.
12v Go to step 4.
12v Repair open or
bad connection
in CKT59
between oil
pressure gauge
and G4.
Go to step 5.
Replace the
sending unit.
12-73
No
Go to step 2.
Go to step 3.
Repair open,
bad connection
or short in
CKT30 between
oil pressure
gauge and fuse
4B.
Replace the
temperature
gauge.
Repair open, or
bad connection
in CKT39
between gauge
and sending
unit.
4-1-00