Line Pressure Test; Recommended Fluid - Hummer H1 Service Manual

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Line Pressure Test

1. Check and adjust fluid level if necessary.
2. Raise vehicle on hoist
3. Connect pressure gauge to transmission test port
(Figure 5-16). Gauge must have 325-350 psi (2240-2413
kPa) capacity.
4. Start engine and check pressures in Park, Neutral and both
Drive ranges. Pressure should be a minimum of 35 psi
(241 kPa) at idle and increase to a maximum of 171 psi
(1179 kPa) at greater throttle openings.
5. Shift transmission into reverse and note pressure. At idle,
pressure should be a minimum of 67 psi (462 kPa) and
increase to a maximum of 324 psi (2234 kPa) as throttle
opening increases.
6. Stop engine, remove gauge, and lower vehicle.
7. If pressures were low in all ranges, pump may need repair
or replacement. Problem may be worn, damaged gears,
blown out cup plug, cross leakage, or worn bushing. If
pressure is high, fault may be with pressure control
solenoid, reverse/boost or pressure regulator valves, bad
PCM ground or solenoid connection.
PRESSURE GAUGE
Figure 5-16: Pressure Gauge
Pressure Control Solenoid Test
1. Connect scan tool to diagnostic/data link connector.
2. Connect pressure test gauge to transmission.
3. Check fluid level and top off if necessary.
4. Shift into Park and apply parking brakes.
5. Start and operate engine at idle speed.
6. Access "override pressure control solenoid" test on scan
tool.
7. Increase current to pressure control solenoid in amp
increments shown in chart (Figure 5-17), and record
pressure gauge readings. Allow gauge readings to stabilize
for 3-5 seconds after each current change.
8. Stop engine and remove test tools.
9. Compare test pressure readings with charge readings.
Pressures should decrease as current to solenoid is
increased. Consistently high pressures indicate a fault in
the PCM, related wiring, or solenoid. Low pressures
indicate an oil pump fault, or hydraulic circuit fault.
05745159
TRANSMISSION
TEST PORT

RECOMMENDED FLUID

The recommended and preferred fluid for 4L80-E transmis-
sions is Dexron III.
In cases where Dexron III is not readily available, Dexron IIE
can be used to top off the fluid level. It is not, however, recom-
mended for use as the primary fluid for a fluid change.
Fluid Capacity
Fluid capacity of the 4L80-E used in Hummer vehicles is:
NOTE: Always fill transmission using the dipstick level as a
guide. Residual fluid left in the transmission during service
could result in an overfilled condition.
Transmission/Transfer Case
Amp Feed To Pressure
Control Solenoid (From
PCM)
0.0-0.02
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
0.98-1.1
Figure 5-17: Pressure Control Solenoid Test
Specifications
• Transmission refill capacity (after filter change) is ap-
proximately 7.7 qts. (7.3 L).
• Dry fill capacity (after overhaul) is approximately 13.5
qts (12.8 L)
• Cooler and line capacity is approximately 1-2 pts (.47-
.95 L)
5-15
Line Pressure - PSI (kPa)
157-177 (1083-1220)
151-176 (1041-1214)
140-172 (965-1186)
137-162 (945-1117)
121-147 (834-1014)
102-131 (703-903)
88-113 (607-779)
63-93 (434-641)
43-73 (296-503)
37-61 (255-421)
35-55 (241-379)