Hummer H1 Service Manual page 1105

38.2 PCM/Tech 1 Scan Tool
• A history DTC will clear after forty consecutive warm
up cycles, if no failures are reported by this and any
other emission related diagnostic.
• PCM battery voltage is interrupted.
• Using a scan tool.
Diagnostic Aids
• Using "Freeze Frame" and/or "Failure Records" data
may aid in locating an intermittent condition. If the DTC
cannot be duplicated, the information included in the
"Freeze Frame" and/or "Failure Records" data can be
useful in determining how many miles since the DTC
set. The Fail Counter and Pass Counter can also be used
to determine how many ignition cycles the diagnostic
reported a pass and/or a fail. Operate the vehicle within
the same freeze frame conditions (RPM, load, vehicle
speed, temperature etc.). that were noted. This will iso-
late when the DTC failed.
• If other DTCs are set that share the same ground and/or
5.0 volt reference circuit, check for faulty connections
and for faulty wiring.
3-1-01
___________________________________________________
Temperature VS Resistance.
˚C
100
90
80
70
60
50
45
40
35
30
25
20
15
10
5
0
-5
-10
-15
-20
-30
-40
Values are Approximate
• If the engine has been allowed to sit overnight, the en-
gine coolant temperature and intake air temperature val-
ues should display within a few degrees of each other.
• If the engine coolant temperature exceeds 60˚C (140˚F),
this indicates that the engine is capable of reaching the
proper temperature, but not necessarily in the correct
amount of time. This diagnostic table must be repeated
on a cold engine, engine coolant and intake air tempera-
ture less than 50˚C (122˚F) and within 3˚C (5˚F) of each
other. The time required to reach the temperature thresh-
old must be measured. When starting a cold engine,
measure the amount of time it takes the engine to reach
the specified temperature. The engine should reach the
specified temperature within 8 minutes. If the specified
temperature is not reached within 7 minutes, check the
following:
Coolant level.
Thermostat operation.
Cooling fan.
˚F OHMS
212 177
194 241
176 332
158 467
140 667
122 973
113 1188
104 1459
95 1802
86 2238
77 2796
68 3520
59 4450
50 5670
41 7280
32 9420
23 12300
14 16180
5 21450
-4 28680
-22 52700
-40 100700
®