Automatic Transmission - 4L80-E/4L85-E (Introduction, Service & Replacement): Overview Chevrolet Silverado 3500

Automatic Transmission Schematic Icons

Automatic Transmission Schematic Icons Icon Icon Definition NOTE: The OBD II symbol is used on the circuit diagrams in order to alert the technician that the circuit is essential for proper OBD II emission control circuit operation. Any circuit which fails and causes the malfunction indicator lamp (MIL) to turn ON, or causes emissions-related component damage, is identified as an OBD II circuit. IMPORTANT: Twisted-pair wires provide an effective "shield" that helps protect sensitive electronic components from electrical interference. If the wires were covered with shielding, install new shielding. In order to prevent electrical interference from degrading the performance of the connected components, you must maintain the proper specification when making any repairs to the twisted-pair wires shown : The wires must be twisted a minimum of 10 turns per 31 cm (12 in) as measured anywhere along the length of the wires The outside diameter of the twisted wires must not exceed 6.0 mm

Scheme 366

Scheme 367

Scheme 368

Scheme 369

Scheme 370

Scheme 371

Scheme 372

Scheme 373

Scheme 374

Scheme 375

Scheme 376

Scheme 377

Scheme 378

Scheme 379

Scheme 380

Scheme 381

Scheme 382

Scheme 383

Scheme 384

Scheme 385

Scheme 386

Scheme 387

Scheme 388

Scheme 389

Scheme 390

Transmission General Description

The 4L80-E is a fully automatic rear wheel drive electronically controlled transmission. The 4L80-E provides four forward ranges, including overdrive and reverse. A gear type of oil pump controls shift points. The powertrain control module (PCM) and the pressure control (PC) solenoid, force motor, regulate these shift points. The PCM also controls shift schedules and TCC apply rates. Transmission temperature also influences shift schedules and TCC apply rates.

You can operate the transmission in any one of the following seven modes

1. P - PARK position prevents the vehicle from rolling either forward or backward on vehicles less than 15,000 G.V.W. For safety reasons, use the parking brake in addition to the park position.
2. R - REVERSE allows the vehicle to be operated in a rearward direction.
3. N - NEUTRAL allows the engine to be started and operated while driving the vehicle. If necessary, you may select this position in order to restart the engine with the vehicle moving.
4. OD - OVERDRIVE is used for all normal driving conditions. Overdrive provides four gear ratios plus a converter clutch operation. Depress the accelerator in order to downshift for safe passing.
5. D - DRIVE position is used for city traffic, and hilly terrain. Drive provides three gear ranges. Depress the accelerator in order to downshift.
6. 2 - Manual SECOND provides acceleration and engine braking or greater traction from a stop. When you choose manual SECOND, the vehicle will start out in first gear and upshift to second gear. You may select this gear at a vehicle speed of up to 22 km/h (35 mph).
7. 1 - Manual LOW provides maximum engine braking. You may select this gear at a vehicle speed of up to 13 km/h (20 mph).

Transmission Component and System Description

The mechanical components of this unit are as follows

1. A torque converter with a torque converter clutch (TCC)
2. A gear type oil pump
3. Five multiple disk clutches
4. Two band assemblies
5. Three planetary gear sets
6. One sprag clutch
7. Two roller clutches
8. A control valve body assembly

The electrical components of this unit are as follows

1. Two shift solenoid valves, 1-2 and 2-3
2. A torque converter clutch (TCC) solenoid valve
3. A transmission pressure control (PC) solenoid valve
4. An automatic transmission fluid temperature (TFT) sensor
5. An automatic transmission fluid pressure (TFP) manual valve position switch assembly
6. An output speed sensor (OSS)
7. An input speed sensor (ISS)

For more information refer to Electronic Component Description .