Chevrolet Silverado / GMC Sierra. Service manual — part 1027

Any of the following bushing conditions require replacement of the bushing and/or housing:

Discoloration due to heat distress

Misalignment or displacement of bushing as a result of spinning in housing

Medium to heavy scoring that can be easily detected with fingernail. Light scoring is a
normal condition.

Debris embedded into the bushing lining material

Obvious damage, including excessive and uneven wear

Excessive polishing. Minor polishing of the bushing is an indication of normal wear and
does not require replacement.

Any of the following conditions require replacement of the bushing's mating shaft:

Discoloration due to heat distress

Rough surface finish that can be easily detected with finger

Obvious shaft abnormalities, including warping or uneven surfaces

Obvious damage or cracking

TRANSMISSION OVERHEATS

Transmission Overheats

OIL PRESSURE HIGH OR LOW

Checks

Causes

TCC Circuit

Blockage during apply or release

Pump Cover (215)

Cross channel leakage

Pressure Regulator Valve
(216)

The valve is stuck in a high demand position

Oil Cooler

The cooler or the cooler lines are blocked

Oil Pan Gasket (73)

The gasket is damaged

Turbine Shaft O-ring (618) The O-ring is damaged
Turbine Shaft Seals (619)

The seals are damaged

Stator Shaft Bushings
(234/241)

The bushing is worn or damaged

Fluid

The fluid level is low

Radiator

Air flow is restricted or internal blockage

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Oil Pressure High or Low

Checks

Causes

ECM Torque Related DTCs
are set

DTCs can cause the engine torque value used by the TCM to
become invalid. When the engine torque is invalid, the TCM
will command maximum line pressure to protect the
transmission.

Oil Pump Assembly (4)

Pressure regulator valve stuck

Pressure regulator valve spring

Rotor guide omitted or misassembled

Rotor cracked or broken

Reverse boost valve or sleeve stuck, damaged or
incorrectly assembled

Orifice hole in pressure regulator valve plugged

Sticking slide or excessive rotor clearance

Pressure relief ball not seated or damaged

Porosity in pump cover or body

Wrong pump cover

Pump faces not flat

Excessive rotor clearance

Oil Filter (72)

Intake pipe restricted by casting flash

Cracks in filter body or intake pipe

O-ring seal missing, cut or damaged

Wrong grease used on rebuild

Control Valve Body (60)

Manual valve scored or damaged

Spacer plate or gaskets incorrect, misassembled or
damaged

Face not flat

2-3 Shift valve stuck

Checkballs omitted or misassembled

Pressure Control Solenoid
(377)

Damage to electrical terminals

Transmission Fluid Pressure
Manual Valve Position
Switch (69)

Contamination

Damaged seals

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

HARSH SHIFTS

Harsh Shifts

INACCURATE SHIFT POINTS

Inaccurate Shift Points

Case (103)

Case to control valve body face not flat

System Voltage

12 volts not supplied to transmission

Electrical short (pinched solenoid wire)

Solenoid not grounded

Checks

Causes

Throttle Position Sensor

Open or shorted circuit

Vehicle Speed Sensor (36)
or Input Speed Sensor (250)

Open or shorted circuit

Automatic Transmission
Fluid Pressure (TFP) (69)

Contamination

Damaged seals

Trans Fluid Temperature
Sensor (Part of 69)

Open or shorted circuit

Engine Coolant Temperature
Sensor

Open or shorted circuit

Pressure Control Solenoid
(377)

Damage to electrical terminals

Contamination

Checks

Causes

Oil Pump Assembly (4)

Stuck pressure regulator valve

Sticking pump slide

Valve Body Assembly (60) Spacer plate or gaskets misassembled, damaged or incorrect
Case (103)

Porous or damaged valve body pad

2-4 Servo Assembly

2-4 accumulator porosity

Damaged servo piston seals

Apply pin damaged or improper length

2-4 Band Assembly

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

FIRST GEAR RANGE ONLY - NO UPSHIFT

1st Gear Range Only - No Upshift

SLIPS IN FIRST GEAR

Slips in 1st Gear

Burned

Anchor pin not engaged

Throttle Position Sensor

Disconnected

Damage

Vehicle Speed Sensor (36)
or Input Speed Sensor (250)

Disconnected

Damaged

Bolt not tightened

4WD Low Switch

Disconnected

Damaged

Checks

Causes

Control Valve Body (60)

The 1-2 Shift valve is sticking

The spacer plate or gaskets are mispositioned or
damaged

Case (103)

The case to valve body face is damaged or is not flat

Shift Solenoid Valves
(366/368)

Stuck or damaged

Faulty electrical connection

2-4 Servo Assembly (13-28)

The apply passage case is restricted or blocked

Nicks or burrs on the servo pin or on the pin bore in the
case

Fourth servo piston is installed backwards

2-4 Band Assembly (602)

The 2-4 band is worn or damaged

The band anchor pin is not engaged

Checks

Causes

Forward Clutch Assembly
(646-651)

Clutch plates worn

Porosity or damage in forward clutch piston

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado