Hummer H1 (2002+). Instruction - page 61

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Transmission/Transfer Case 5-43

®

05745159

NOTE:

Some corrections indicated in the table below may not be allowed on vehicles covered under the provisions of the war-

ranty policy. The proper correction may be transmission replacement. Contact the AMG warranty department for direction in such
cases.

TRANSMISSION DIAGNOSIS GUIDE

Problem

Potential Cause

Correction

Fluid Leaking
Out of Vent
and/or Foaming

1.

Transmission overfilled.

1.

Drain Excess Fluid off through fill tube. Use
suction gun and small diameter plastic or
teflon tubing.

2.

Wrong or contaminated fluid.

2.

Drain and change fluid and filter. May also be
necessary to remove and drain converter.

3.

Air entering fluid due to cross leakage at
improperly seated pump cover or filter.

3.

Reseat filter. Remove transmission and reseat
pump if necessary.

4.

Transmission overheat. Caused by:

• low fluid level

• blocked oil cooler

• full load hot climate temperature operation

• converter clutch valve or spring failure

• converter stator locked (seized) and will not

free wheel at coupling speed

4.

Correct low fluid level and check for leaks.
Reduce engine/transmission load. Replace
transmission if clutch valve or spring
condition exists. Replace plugged, damaged
cooler.

Transmission
Overheat

1.

Low fluid level.

1.

Add fluid and check for leaks.

2.

Oil cooler problem:

• Fins blocked with dirt, debris

• cooler partially plugged

• cooler (or lines) leaking

2.

Clean dirt/debris with water spray. Replace
leaking or plugged cooler. Replace leaking
cooler lines or fittings.

3.

Converter clutch stuck in applied position.

3.

Replace converter.

4.

Converter clutch valve, limit valve, or enable
valve or spring failure.

4.

Replace transmission.

5.

Oil pump or body seal not seated causing
cross leakage. May be accompanied by fluid
foaming and leakage out vent.

5.

Remove pump and replace seal. Be sure pump
body is properly seated.

6.

Pressure regulator valve stuck in high demand
position.

6.

Remove oil pump and free up valve.

7.

Converter stator clutch seized (locked).
Engine overheat may also occur.

7.

Replace converter.

Line Pressure
Too High or
Too Low

1.

Oil pump problem:

• loose PCM connection

• seals failed

• gears damaged

• bushing worn, scored

• pressure regulator valve or spring fault

• reverse/boost valve fault

• pressure relief spring collapsed, broken

• loose pump bolts

1.

Repair loose connection. Replace transmission
if pump is damaged.

2.

Pressure control solenoid failed OFF or ON.

2.

Replace solenoid

3.

TCM/PCM fault.

3.

Replace TCM/PCM.

5-44

Transmission/Transfer Case

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®

Vehicle Creeps
In Neutral

1.

Manual valve mispositioned or stuck.

1.

Remove valve body and repair as needed.

2.

Forward clutch fault.

2.

Replace transmission.

Vehicle Moves
In Park

1.

Manual linkage loose, damaged, misadjusted,
disconnected.

1.

Repair or adjust linkage as required

2.

Park pawl, spring, or gear damaged.

2.

Inspect and replace pawl, spring, or gear.

Vehicle Won’t
Move In Drive
Range

1.

Low fluid level.

1.

Top off fluid level. If transmission now oper-
ates properly, locate and correct leaks.

2.

Shift linkage misadjusted, disconnected, loose.

2.

Correct as required.

3.

Pressure switch assembly fault.

3.

Replace switch assembly.

4.

Low fluid pressure caused by oil pump fault:
• worn bushing
• failed seal
• broken gears
• loose bolts

4.

Remove pump and replace seal. Replace
transmission if pump is damaged.

5.

Transmission case seal, or gasket failure.

5.

Locate and replace leaking gasket or seal.

6.

Input or turbine shaft damage (splines worn,
shaft broken)

6.

Replace transmission if either shaft is
damaged.

7.

Roller clutch failure.

7.

Replace transmission.

8.

Torque converter hub damage.

8.

Replace converter.

9.

Forward clutch problem:
• piston seal failure
• clutch plates burned, damaged, missing
• burned reaction plate
• worn teeth
• failed check ball

9.

Replace transmission.

10. Rear planetary gear set damage:

• broken pinions

• sun gear damage

10. Replace transmission.

11. Park pawl spring broken.

11. Replace spring.

12. Turbine shaft ball not seating.

12. Replace transmission.

13. Mainshaft splines damaged.

13. Replace transmission.

Vehicle Won’t
Back Up (No
Reverse)

1.

Low fluid level.

1.

Top off fluid. If vehicle now backs up, check
and correct fluid leaks.

2.

Shift linkage loose, misadjusted, damaged.

2.

Repair linkage.

3.

Reverse servo fault:

• misassembled

• piston or seal damage

3.

Overhaul servo.

4.

Rear band fault:
• wrong band apply pin
• band worn

4.

Check and replace apply pin.

5.

Direct clutch fault:
• worn, damaged clutch plates
• check ball leaking or missing

5.

Replace transmission.

TRANSMISSION DIAGNOSIS GUIDE (Cont’d)

Problem

Potential Cause

Correction

____________________________________________

Transmission/Transfer Case 5-45

®

05745159

6.

Overdrive roller clutch failure.

6.

Replace transmission.

7.

Valve body fault:
• manual valve stuck, damaged
• Pressure switch failure

7.

Remove and free-up binding valves. Replace
switch assembly if failed. Replace trans-
mission if valve body bores are damaged.

Engine Stalls
When Trans-
mission Is
Shifted Into
Gear

1.

Idle speed incorrect (too low).

1.

Check PCM operation with scan tool on turbo
diesel.

2.

Torque converter clutch stuck in applied posi-
tion, or clutch is dragging.

2.

Check converter clutch valve and solenoid
operation. If OK, replace converter.

3.

Forward clutch seized.

3.

Replace transmission.

4.

Fourth clutch seized or dragging.

4.

Replace transmission.

Slips In Drive/
Reverse

1.

Low fluid level.

1.

Top off fluid level and check for leaks.

2.

Low fluid pressure.

2.

Check line pressure and overhaul pump if low.

3.

Reverse servo seal failure (reverse range only).

3.

Overhaul servo.

No First Gear
In Either D
Range

1.

Low roller clutch failure (not attached or bro-
ken).

1.

Replace transmission.

2.

Center support race, splines, or snap ring fail-
ure.

2.

Replace transmission.

3.

Forward clutch problem.

3.

Replace transmission.

4.

Overdrive roller clutch problem.

4.

Replace transmission.

5.

Shift solenoid fault (either solenoid).

5.

Check with scan tool and replace as needed.

No First Gear in
1 Range (Man-
ual Low)

1.

Low roller clutch failure.

1.

Replace transmission.

2.

Center support fault:

• race broken

• splines damaged

• snap ring not seated

• case damaged

2.

Replace transmission.

3.

Forward clutch fault.

3.

Replace transmission.

4.

Overdrive roller clutch failure.

4.

Replace transmission.

5.

Rear band fault:

• band worn

• servo failure

• incorrect apply pin

5.

Replace transmission.

6.

Shift solenoid fault.

6.

Check A and B solenoids with scan tool and
repair as needed.

No Second
Gear

1.

Overdrive roller or intermediate sprag clutch
damage.

1.

Replace transmission.

2.

Center support problem:

• snap ring not seated

• splines or race damaged

• support bolt missing, damaged

2.

Replace transmission.

TRANSMISSION DIAGNOSIS GUIDE (Cont’d)

Problem

Potential Cause

Correction

5-46

Transmission/Transfer Case

_____________________________________________

®

3.

Intermediate clutch air bleed cup plug leaking
or missing.

3.

Replace transmission.

4.

Overrun clutch fault.

4.

Replace transmission.

5.

Forward clutch fault.

5.

Replace transmission.

6.

Intermediate clutch fault.

6.

Replace transmission.

7.

Shift solenoid fault.

7.

Check with scan tool (both solenoids should
be off.)

No Third Gear

1.

PCM ground wire fault.

1.

Repair bad connection.

2.

No feed voltage to shift solenoid B (2-3).

2.

Locate and repair open in wire harness.

3.

Shift solenoid fault.

3.

Test with scan tool (B should be on and A
should be off). Replace failed solenoid.

4.

Direct clutch check ball stuck closed (partial
apply and drag)

4.

Replace transmission.

5.

Intermediate sprag clutch fault.

5.

Replace transmission.

6.

Center support fault:

• snap ring not seated

• bolt missing or broken

• support worn or damaged

6.

Replace transmission.

7.

Forward or direct clutch pack problem.

7.

Replace transmission.

No Overdrive
Fourth Gear

1.

Shift solenoid A or B problem:

• loss of supply voltage

• shorted/open solenoid

• bad ground

• leaking O-ring

1.

Check and repair solenoid feed wiring.
Replace either solenoid if open or shorted. Use
scan tool to check (both solenoids should be
on).

2.

Pressure switch fault.

2.

Replace switch.

3.

PCM ground fault.

3.

Repair bad ground connection.

4.

Fourth clutch or overrun clutch failure.

4.

Replace transmission.

5.

Forward and clutch or direct clutch failure.

5.

Replace transmission.

First and Fourth
Gear Only - or -
Manual Second
and Third Only

1.

Shift solenoid A stuck in off position.

1.

Replace solenoid.

2.

Voltage supply wire to solenoid a is loose,
shorted, or open.

2.

Locate and repair wire problem.

3.

Fault in PCM ground.

3.

Locate and repair bad connection.

4.

Filter

plugged.

4.

Change fluid and replace filter. Replace
transmission if filter is full of clutch material.
Dented oil pan can obstruct filter and cause
this problem

5.

2-3 shift valve stuck.

5.

Replace valve, spring, or valve body if valve
bore is damaged.

First and Sec-
ond Gear Only

1.

Shift solenoid B stuck in off position, or not
connected to PCM.

1.

Replace solenoid if seized. Repair wire con-
nections to PCM if necessary.

2.

Feed wire to shift solenoid B open/shorted.

2.

Repair wire or replace harness as required.

TRANSMISSION DIAGNOSIS GUIDE (Cont’d)

Problem

Potential Cause

Correction

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