Hummer H1 Service Manual page 293

5-94 Transmission/Transfer Case
Diagnostic Aids
• Inspect the wiring for poor electrical connections at the
PCM and at the transmission 20-way connector. Look
for possible bent, backed out, deformed or damaged ter-
minals. Check for weak terminal tension as well. Also
check for a chafed wire that could short to bare metal or
other wiring. Inspect for a broken wire inside the insula-
tion.
• When diagnosing for a possible intermittent short or
open condition, move or massage the wiring harness
while observing test equipment for a change.
• An open ignition feed circuit can cause multiple DTCs
to set.
• If any engine DTCs or TPS codes are present diagnose
and clear these DTCs first. Then check to see if the
transmission DTCs have reset.
Step
1 1. Connect scan tool.
2. Turn ignition switch to the "Run" position.
NOTE: Important: Before clearing DTC(s), use the
scan tool to record "Freeze Frame" and "Failure
Records" for reference, as data will be lost when the
"Clear Info" function is used.
3. Record DTC "Freeze Frame" and "Failure
Records."
Were DTCs P0753, P0758, P1860, P1864, and P1886
set?
2 1. Inspect applicable fuse.
2. If fuse was blown, Inspect/Repair circuit to sole-
noid, and internal wiring harness for short to
ground.
Was problem found and corrected?
3 Using the transmission output control function on the
scan tool, command the 1-2 shift solenoid "ON" and
"OFF" three times while listening to transmission pan
with stethoscope.
Does solenoid click when commanded?
3-1-01
_____________________________________________
DTC P0753 1-2 Shift Solenoid Valve Electrical
Action
4L80-E CHART
1-2 Shift
Gear
Solenoid
1 ON
2 OFF
3 OFF
4 ON
Test Description
The numbers below refer to the step numbers on the diagnostic
chart.
3. This test checks the function of the 1-2 shift solenoid
and the internal wiring harness.
5. This test checks for power to the 1-2 shift solenoid
from the ignition through the fuse.
13. This test measures the resistance of the component.
Value
—
—
—
2-3 Shift
Solenoid
OFF
OFF
ON
ON
Yes No
Go to step 2. Go to step 3.
Go to Step 15. Go to step 4.
Go to diagnos- Go to step 4.
tic aids.
®