Hummer H1 Service Manual page 851

12-78 Electrical System
Step
4 With ignition on, using a DVOM set to measure
voltage and using J–35616-92 test adapters probe
the GN wire (CKT 399) with the positive lead.
Place the negative lead on a known good ground.
Is voltage present?
5 With the ignition off, and using a DVOM set to
measure ohms, check for resistance between the
BK wire (CKT 58) of the temperature blend door,
and a good ground. Does resistance exceed speci-
fications?
6 Using a DVOM set to read volts, the ignition
switch on the run position, and using J–35616-92
test adapters, probe the blue wire (CKT 402) with
the positive lead, and the BK wire (CKT 58) with
the negative lead. Rotate temperature control dial
on the HVAC control head from cold to hot and
back. Is voltage present at the cold setting and 0v
on the hot setting?
7 Disconnect the 8 wire connector at the HVAC
control head. Using a DVOM set to measure
ohms, check resistance between pin F (CKT 402)
of the 8 wire connector and the blue wire (CKT
402) of the temperature blend door connector.
Does resistance exceed specifications?
8 Check for open or bad connection between the
HVAC control head 8 wire connection and the
temperature blend door motor connection. Check
for loose terminals at the control head. Was a bad
connection found?
9 Using a DVOM set to measure voltage, probe pin
E (CKT 399) of the 8 wire connector on the
HVAC control head with the positive lead, and
pin B (CKT 58) of the three wire HVAC control
head connector with the negative lead. With igni-
tion on, is voltage present?
10 Using a DVOM set to measure voltage, probe pin
E (CKT 399) of the HVAC control head eight
wire connector with the positive lead. Attach the
negative lead to a known good ground. With the
ignition switch in the run position, is voltage
present?
4-1-00
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HVAC Temperature Door Inoperative (Continued)
Action Value(s) Yes
12v Go to step 5.
<.2 Ω
Locate open or
bad connection
between tem-
perature blend
door motor and
G4.
Cold = 12v Replace the
Hot = 0v temperature
Cold = 12v blend door
motor.
62K Ω
Go to step 9.
Repair or
replace harness
as necessary.
12v Replace faulty
HVAC control
head.
12v Go to step 11.
®
No
Repair open or
short to ground
between tem-
perature blend
door motor and
fuse 7C.
Go to step 6.
Go to step 7.
Go to step 8.
Go to step 9.
Go to step 10.
Locate short or
open between
the HVAC con-
trol head and
fuse 7C.