Hummer H1 (2002+). Manual - part 62

____________________________________________

 Transmission/Transfer Case  5-47

®

05745159

No Torque 
(Drive) In Sec-
ond

1.

Worn or damaged intermediate sprag clutch.

1.

Replace transmission.

No Overrun 
Braking In:

1.

Rear band or servo fault.

1.

Replace transmission.

2.

Main or output shaft damage.

2.

Replace transmission.

First (1)

3.

Lo roller or sprag clutch fault.

3.

Replace transmission.

-OR-
Second (2)

1.

Front band worn, wrong apply pin, or servo 
problem.

1.

Replace transmission.

2.

Direct clutch housing fault.

2.

Replace transmission.

3.

Overrun clutch fault.

3.

Replace transmission.

4.

Rear gear set problem.

4.

Replace transmission.

Second and 
Third Gear 
Only In D 
Range

1.

Shift solenoid A in off position:

• open voltage feed wire

• bad PCM ground

• solenoid seized

1.

Repair solenoid feed or PCM ground wire as 
needed. Replace solenoid if stuck closed.

2.

1-2 shift valve fault.

2.

Replace valve body if 1-2 valve is scored or
spring has collapsed.

Converter 
Clutch will Not 
Release or Will 
Not Apply

1.

PCM, or pulse width solenoid wiring fault 
(short, open, ground).

1.

Locate and repair wiring problem as needed.

2.

Fluid contamination.

2.

Drain-change fluid and filter. flush cooler and
lines. Replace converter.

3.

Converter clutch solenoid fault.

3.

Test with scan tool and replace if inoperative.

4.

Fault with converter clutch, enable, or limit 
valves.

4.

Remove oil pump and inspect valves (or pump
body) if damaged. Smooth minor burrs, nicks
with crocus cloth.

5.

PCM fault.

5.

Test with scan tool and replace if fault is
discovered.

6.

Converter clutch failure.

6.

Replace converter.

7.

Brake switch inoperative.

7.

Replace switch if open or shorted.

8.

Turbine shaft seal leak.

8.

Replace transmission.

Converter 
Clutch Slips or 
Soft Apply

1.

Low fluid level.

1.

Top off and check for leaks.

2.

Fluid contaminated or wrong fluid.

2.

Drain and change fluid and filter. Flush cooler
and lines.

3.

Turbine shaft seal leak.

3.

Replace seals.

4.

Oil pump bushing worn.

4.

Replace bushing.

5.

Low fluid pressure.

5.

Test pressure and replace transmission if
necessary.

6.

Converter clutch (pulse width) solenoid fault.

6.

Check  solenoid  wiring.  If  OK,  replace
solenoid.

 TRANSMISSION DIAGNOSIS GUIDE (Cont’d)

Problem

Potential Cause

Correction

5-48

Transmission/Transfer Case

_____________________________________________

®

Converter 
Clutch Apply 
Timing Incor-
rect

1.

Incorrect sensor input signal to PCM caused 
by inoperative sensor.

1.

Test operation of all sensors with scan tool. 
Replace failed sensors as needed.

2.

PCM problem.

2.

Test with scan tool. Repair wires or module as
required.

Harsh Shifts 
(All Drive 
Ranges)

1.

Pressure control solenoid stuck in off (de-
energized) position.

1.

Replace solenoid.

2.

Accumulator fault:

• piston spring broken

• piston seal damage

• piston spring missing

• cover bolts loose

• gasket damaged

2.

Overhaul accumulator.

3.

Valve body check ball missing or misposi-
tioned.

3.

Reposition check balls. Replace transmission
if any check balls are missing.

4.

Incorrect PCM calibration.

4.

Replace PCM.

Harsh Engage-
ment In Drive 
and Reverse

1.

High idle speed.

2.

Line pressure too high:
• pressure control solenoid failed
• reverse/boost, or pressure regulator valve stuck
• accumulator spring or seal failure
• shift sensor failure
• missing valve body check ball

1.

Adjust idle or check PCM with scan tool on 
turbo diesel.

2.

Test pressure control solenoid and sensors 
with scan tool and replace as needed. Repair 
accumulator spring, or pressure regulator 
valves as needed.

 TRANSMISSION DIAGNOSIS GUIDE (Cont’d)

Problem

Potential Cause

Correction

 

____________________________________________

 

 Transmission/Transfer Case  5-49

 

 

®

 

05745159

 

DTC P0218 Transmission Fluid Over temperature

 

Circuit Description

 

The flow of transmission fluid starts in the transmission pan. It
is then drawn through the filter and transmission case into the
oil pump assembly. The oil pump assembly pressurizes the
fluid, which becomes the main supply line of fluid. This fluid
is directed to various components and hydraulic circuits within
the transmission. The pressure regulator valve receives this
fluid and directs it to the converter clutch shift valve. The con-
verter clutch shift valve directs hot fluid leaving the torque
converter or regulated converter feed fluid, through the cooler
line to the transmission oil cooler. The transmission oil cooler
is located above the radiator. The cooled fluid (center lube) is
returned to the transmission through the return cooler line and
into center lube port of the transmission. The Automatic Trans-
mission Fluid Temperature (TFT) Sensor, detects the fluid
temperature in the transmission pan.

If the Powertrain Control Module (PCM) detects a high TFT
for a long period of time, then DTC P0218 sets. DTC P0218 is
a type D DTC.

 

Conditions for Setting the DTC

 

• No TFT Sensor DTCs P0712 or P0713

• The TFT is greater than 130°C (266°F)

• All conditions are met for 410 seconds

 

Action Taken When the DTC Sets

 

• The PCM does not illuminate the Malfunction Indicator 

Lamp (MIL).

• The PCM freezes shift adapts from being updated.

• DTC P0218 is stored in the PCM history.

 

Conditions for Clearing the DTC

 

• A scan tool can clear the DTC from the PCM history. 

The PCM clears the DTC from the PCM history if the 
vehicle completes 40 warm-up cycles without a failure 
reported.

• The PCM cancels the DTC default actions when the 

fault no longer exists and the ignition is off long enough 
in order to power down the PCM.

 

Diagnostic Aids

 

• Inspect the cooling system fluid level and condition.

• Verify the customer’s driving habits, such as trailer tow-

ing, etc.....

• The scan tool Trans. Fluid Temp. (TFT) should rise 

steadily during warm-up cycles then stabilize.

• DTC P0218 may set approximately 600 seconds after 

DTC P0711 has set. Follow the diagnostic table for the 
DTC P0711. Repairing the condition that set DTC 
P0711 will likely eliminate DTC P0218.

• First diagnose and clear any engine DTCs or APP codes 

that are present. Then inspect for any transmission 
DTCs that may have reset.

 

Test Description

 

The numbers below refer to the step numbers on the diagnostic
table.

3. DTC P0711 may also set a DTC P0218. Go to the DTC
P0711 table for diagnosis.

4. This step inspects for air restrictions and loss of transmission
fluid flow, causing an extremely high TFT.

 

3-1-01

5-50

Transmission/Transfer Case

_____________________________________________

®

.

 DTC P0218 Transmission Fluid Overtemperature 

Step

Action

Value(s)

Yes

No

1

Was the Powertrain On-Board Diagnostic (OBD) 
System Check performed?

Go to step 2

Go to Power-

train OBD Sys-

tem Check

2

Install the scan tool.
WIth the engine off, turn the ignition switch to the 
run positon.
Impotant:

 Before clearing the DTCs, use the 

scan tool to record teh Freeze Frame and Failure 
Records for reference. Using the Clear Info func-
tion erases the stored Failure Records from the 
PCM.
Record the DTC Failure Records then clear the 
DTC.
Perform the Transmission Fluid Checking Proce-
dure.
Was the Transmission Fluid Checking Proceedure 
performed?

Go to step 3

Go to transmis-

sion fluid check-

ing procedure

3

Is DTC P0711 also set?

Go to diagnostic 

aids

Go to step 4

4

Inspect the cooling system for the following con-
ditions:
• Air flow restrictions
• Air flow blockage
Inspect the transmission cooling system for the 
following conditions:
• Air flow restrictions
• Air flow blockage
• Damaged cooler lines or hoses
• Low A/T fluid cooler flow. Refer to A/T cooler 

flow test.

Was the condition found?

Go to step 7

Go to step 5

5

Perform the line pressure check procedure. Refer 
to 4L80-E Line Pressure Check Procedure.
Was the condition found?

Go to step 7

Go to step 6

6

Inspect the torque converter stator for damage. 
Refer to Torque Converter Clutch Diagnosis.
Was the condition found?

Go to step 7

Go to system 

diagnosis table 

“Transmission 

Overheating”

7

In order to verify your repair, perform the follow-
ing procedure:
1.

Select DTC.

2.

Select Clear Info.

3.

Operate the vehicle under the following con-
ditons.

• Turn the ignition switch to the RUN position.
• The TFT must be less than 129°C (264°F) for at 

least 5 seconds.

4.

Select Specific DTC. Enter P0218.

5.

Has the test run and passed?

System OK

Begin the diag-
nosis again. Go 

to step 1