Automatic Transmission - 4l80-e/4l85-e (Introduction, Service & Replacement) Chevrolet Chevy Express G3500

Transmission Fluid Temperature (TFT) Sensor Specifications

Transmission Fluid Temperature (TFT) Sensor Specifications

Fastener Tightening Specifications

Fastener Tightening Specifications

Transmission General Specifications

Transmission General Specifications

Fluid Capacity Specifications

Fluid Capacity Specifications

Range Reference

Range Reference

Shift Solenoid Valve State and Gear Ratio

Shift Solenoid Valve State and Gear Ratio; 4L80-E

Shift Speed

Shift Speed

Transmission Range Switch Logic

Transmission Range Switch Logic

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic

Transmission Fluid Pressure (TFP) Manual Valve Position Switch Logic

Line Pressure

Line Pressure

Component Resistance

Component Resistance

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

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Automatic Transmission Inline 20-Way Connector End View

Inline Harness Connector End - Engine Side Connector Part Information 12160493 14F Micro-Pack 100W Series (GY) Pin Wire Color Circuit No. Function A L-GN 1222 1-2 Shift Solenoid Valve Control B YE/BK 1223 2-3 Shift Solenoid Valve Control C RD/BK - Early Production OG/BK - Late Production 1228 Pressure Control (PC) Solenoid Valve Controlled Power D L-BU/WH 1229 PC Solenoid Valve Controlled Ground E PK 1020 Transmission Solenoid Power F-K - - Not Used L YE/BK 1227 Transmission Fluid Temperature (TFT) Sensor Signal M BK - Early Production TN - Late Production 2762 TFT Sensor Ground N PK 1224 TFP Switch Signal A P RD - Early Production OG - Late Production 1226 TFP Switch Signal C R D-BU 1225 TFP Switch Signal B S BN 418 Torque Converter Clutch (TCC) Solenoid Valve Control T-W - - Not Used

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Inline Harness Connector End - Transmission Side Connector Part Information 12160782 14M Micro-Pack 100W Series (GY) Pin Wire Color Circuit No. Function A L-GN 1222 1-2 Shift Solenoid Valve Control B YE 1223 2-3 Shift Solenoid Valve Control C PU 1228 Pressure Control (PC) Solenoid Valve Controlled Power D L-BU 1229 PC Solenoid Valve Controlled Ground E RD 839 Transmission Solenoid Power F-K - - Not Used L BN 1227 Transmission Fluid Temperature (TFT) Sensor Signal M GY 452 TFT Sensor Ground N PK 1224 TFP Switch Signal A P OG 1226 TFP Switch Signal C R D-BU 1225 TFP Switch Signal B S BK 418 Torque Converter Clutch (TCC) Solenoid Valve Control T-W - - Not Used

Automatic Transmission Internal Connector End Views

Automatic Transmission Fluid Pressure Manual Valve Position Switch Connector End , Wiring Harness Side Connector Part Information 12162200 Conn 3F M/P 150.2 P2S (RD) Pin Wire Color Circuit No. Function A PK 1224 Transmission Range Switch Signal A Input B D-BU 1225 Transmission Range Switch Signal B Input C OG 1226 Transmission Range Switch Signal C Input

1-2 Shift Solenoid Valve Connector End , Wiring Harness Side Connector Part Information 12162201 Conn 2F M/P 150.2 P2S (NA) Pin Wire Color Circuit No. Function A L-GN 1222 1-2 Shift Solenoid Valve Control B RD 839B Transmission Solenoid Power

2-3 Shift Solenoid Valve Connector End , Wiring Harness Side Connector Part Information 12162205 Conn 2F M/P 150.2 P2S (M-GY) Pin Wire Color Circuit No. Function A RD 839A Transmission Solenoid Power B YE 1223 2-3 Shift Solenoid Valve Control

Torque Converter Clutch Pulse Width Modulated (TCC PWM) Solenoid Valve Connector End , Wiring Harness Side Connector Part Information 12162205 Conn 2F M/P 150.2 P2S (M-GY) Pin Wire Color Circuit No. Function A RD 839C Transmission Solenoid Power B BK 418 Torque Converter Clutch Pulse Width Modulated (TCC PWM) Solenoid Valve

Pressure Control Solenoid Valve Connector End , Wiring Harness Side Connector Part Information 12146800 Conn 2F M/P 480 SPL (NA) Pin Wire Color Circuit No. Function A PU 1228 Pressure Control (PC) Solenoid Valve HIGH Control B L-BU 1229 PC Solenoid Valve LOW Control

Transmission Fluid Temperature (TFT) Sensor Connector End , Wiring Harness Side Connector Part Information 12047662 CONN 2F M/P 150 (BK) Pin Wire Color Circuit No. Function A BN 1227 Transmission Fluid Temperature (TFT) Sensor Signal B GY 452 TFT Sensor Ground

Automatic Transmission Related Connector End Views

Automatic Transmission Input Shaft Speed (AT ISS) Sensor Connector End Connector Part Information 15359366 ASM 2F M/P 150.2 P2S SLD (BK) Pin Wire Color Circuit No. Function A RD/BK - Early Production OG/BK - Late Production 1230 Transmission Input Speed Sensor Signal High B D-BU/WH 1231 Transmission Input Speed Sensor Signal Low

Vehicle Speed Sensor (VSS) Connector End Connector Part Information 15359366 ASM 2F M/P 150.2 P2S SLD (BK) Pin Wire Color Circuit No. Function A YE 400 Transmission Output Speed Sensor Signal High B PU 401 Transmission Output Speed Sensor Signal Low

Tow/Haul Switch Connector End , Dash Mounted Wiring Harness Side Connector Part Information 12047785 4-Way Conn 4F M/P 150 (BK) Pin Wire Color Circuit No. Function A BK 350 Ground B BN/WH 230 Instrument Panel Lamps Dimming Control C - - Not Used D L-BU 1788 Tow/Haul Switch Signal

Park/Neutral Position (PNP) Switch Connector End Connector Part Information 15416722 BLK ASM Conn 12 F GT Pin Wire Color Circuit No. Function 1 D-GN 1433 PNP/Clutch Start Switch Signal 2-3 - - Not Used 4 YE 772 Transmission Range Switch Signal B 5 BK/WH - Early Production TN/WH - Late Production 771 Transmission Range Switch Signal A 6 GY 773 Transmission Range Switch Signal C 7 BK 1250 Ground 8 WH 776 Transmission Range Switch Signal P 9 L-GN 275 P/N Position Switch Signal 10 L-GN 1324 Back-up Lamp Supply Voltage 11 PK 339 IGN 1 Voltage 12 PK 139 IGN 1 Voltage

Removal Procedure

1. Apply the parking brake.
2. Position the steering column shift lever to park.
3. Remove the knee bolster trim panel. Refer to «Knee Bolster Replacement - Left»(/chevrolet/chevy-express-g3500/1996-2012/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
4. Remove the knee bolster bracket. Refer to «Knee Bolster Bracket Replacement - Left»(/chevrolet/chevy-express-g3500/1996-2012/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
5. Remove the clip securing the shift cable to the steering column bracket.
6. Remove the shift cable from the steering column shift control.
7. Remove the rubber grommet from the floor panel.
8. Remove the air cleaner assembly.
9. Remove the shift cable clips from the left front of the engine compartment.
10. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
11. Remove the shift cable clips from the left rear engine bracket.
12. Remove the shift cable from the stud ball.
13. Remove the locking clip from the cable at the bracket.
14. Lower the vehicle.
15. Remove the shift cable from the vehicle.

Installation Procedure

1. Install the shift cable to the vehicle.
2. Raise the vehicle.
3. Remove the black shipping tab from the transmission end of the shift cable and discard the tab.
4. Install the ball stud on the transmission.
5. Install the shift cable to the transmission bracket.
6. Install the cable clip.
7. Install the shift cable end to the transmission shift control lever by pushing the cable end onto the transmission shift control lever stud ball.
8. Lock the primary lock.
9. Lock the secondary lock.
10. Install the shift cable clips to the engine brackets.
11. Lower the vehicle.
12. Install the rubber grommet to the floor panel.
13. Install the shift cable to the steering column shift control.
14. Install the clip securing the shift cable to the steering column bracket.
15. Install the cable to the shift lever ball stud.
16. Adjust the shift cable. Refer to «Automatic Transmission Range Selector Cable Adjustment»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement__automatic-transmission-range-selector-cable-adjustment) .
17. Install the knee bolster bracket. Refer to «Knee Bolster Bracket Replacement - Left»(/chevrolet/chevy-express-g3500/1996-2012/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.
18. Install the knee bolster trim panel. Refer to «Knee Bolster Replacement - Left»(/chevrolet/chevy-express-g3500/1996-2012/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages and Console.

1. Apply the parking brake.
2. Shift the transmission into neutral.
3. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
4. Disconnect the transmission range selector cable from the shift lever and the bracket (2). Refer to «Automatic Transmission Range Selector Cable Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) .
5. Remove the bolts (1) securing the transmission range selector cable bracket (2) to the transmission.
6. Remove the transmission range selector cable bracket from the vehicle.

1. Install the transmission range selector cable bracket to the vehicle.
2. Install the transmission range selector cable bracket bolts (1). Tighten: Tighten the bolts to 25 N.m (18 lb ft).
3. Install the transmission range selector cable to the bracket (2) and the lever. Refer to «Automatic Transmission Range Selector Cable Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) .
4. Lower the vehicle.
5. Check the vehicle for proper operation. If adjustment of the cable is necessary, refer to «Automatic Transmission Range Selector Cable Adjustment»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement__automatic-transmission-range-selector-cable-adjustment) .

Automatic Transmission Range Selector Cable Adjustment

1. Position the transmission shift control lever into park.
2. Apply the park brake.
3. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
4. Remove the end of the range selector cable from the range selector lever ball stud.
5. Position the transmission range selector lever to park. Rotate the range select lever clockwise until it reaches the full mechanical stop position.
6. Slide the locking tab retainer to the side.
7. Release the locking tab.
8. Install the end of the range selector cable to the range selector lever ball stud.
9. Engage the locking tab without disturbing the cable. This sets the adjustment.
10. Slide the locking tab retainer over the locking tab.
11. Lower the vehicle.
12. Check the transmission for proper operation.
13. Release the parking brake.

Tools Required

J 41364-A Neutral Position Adjustment Tool

1. Apply the parking brake.
2. Shift the transmission into neutral.
3. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
4. Remove the nut securing the transmission control lever to the manual shaft.
5. Remove the transmission control lever from the manual shaft.
6. Disconnect the electrical connectors from the switch.
7. Remove the bolts securing the park/neutral position switch to the transmission.
8. Remove the park/neutral position switch from the manual shaft. If the park/neutral position switch did not slide off the manual shaft, file the outer edge of the manual shaft in order to remove any burrs.

1. Install the switch to the transmission manual shaft by aligning the switch hub flats with the manual shaft flats.
2. Slide the switch onto the transmission manual shaft until the switch mounting bracket contacts the mounting bosses on the transmission.
3. Install the switch to the transmission with two bolts finger tight.
4. Position the tool J 41364-A onto the park/neutral position switch. Ensure that the two slots on the switch where the manual shaft is inserted are lined up with the lower two tabs on the tool.
5. Rotate the tool until the upper locator pin on the tool is lined up with the slot on the top of the switch. Tighten: Tighten the bolts securing the switch to 25 N.m (18 lb ft).
6. Remove the J 41364-A from the switch. If installing a new switch, remove the positive assurance bracket at this time.
7. Connect the electrical connectors to the switch.
8. Install the transmission control lever to the manual shaft with the nut. Tighten: Tighten the control lever nut to 25 N.m (18 lb ft).
9. Lower the vehicle.
10. Check the switch for proper operation. The engine must start in the P (Park) or N (Neutral) positions only. If proper operation of the switch can not be obtained, replace the switch.

Park/Neutral Position Switch Adjustment

1. Place the transmission range selector in the N (Neutral) position.
2. With an assistant in the drivers seat, raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
3. Loosen the park/neutral position switch mounting bolts.
4. With the vehicle in the N (Neutral) position, rotate the switch while the assistant attempts to start the engine.
5. Following a successful start, turn the engine off.
6. Tighten the bolts securing the switch to the transmission. Tighten: Tighten the bolts to 25 N.m (18 lb ft).
7. Lower the vehicle.
8. Check the switch for proper operation. The engine must start in the P (Park) or N (Neutral) positions only.
9. Replace the park/neutral position switch if proper operation can not be achieved. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-introduction-service-replacement) .

1. Remove the instrument panel trim plate bezel. Refer to «Trim Plate Bezel Replacement - Instrument Panel (I/P) Cluster»(/chevrolet/chevy-express-g3500/1996-2012/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages, and Console.
2. Disconnect the electrical connector from the tow/haul switch.
3. Push in clips (1) on both sides of the switch.
4. Push the switch rearward to remove the switch from the trim.

1. Install the switch into the trim plate bezel opening by pushing the switch in until the clip (1) snap into place.
2. Connect the electrical connector to the tow/haul switch.
3. Install the instrument panel trim plate bezel. Refer to «Trim Plate Bezel Replacement - Instrument Panel (I/P) Cluster»(/chevrolet/chevy-express-g3500/1996-2012/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges-and-console) in Instrument Panel, Gages, and Console.

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Place a drain pan under the transmission oil pan.
3. Remove the oil pan drain plug, if equipped.
4. Remove the oil pan bolts.
5. Remove the oil pan.
6. Remove the gasket.
7. Remove the magnet.
8. Remove the oil filter.
9. Remove the filter neck seal.
10. The transmission oil pan gasket is reusable. Inspect the gasket and replace as needed.
11. Clean the transmission case and the oil pan gasket surfaces with solvent.

1. Install the filter neck seal.
2. Install the oil filter.
3. Install the oil pan gasket to the pan.
4. Install the magnet into the bottom of the pan.
5. Install the oil pan to the transmission with seventeen bolts. Tighten: Tighten the oil pan bolts to 11 N.m (97 lb in).
6. Apply a small amount of sealant GM P/N 12346004 to the treads of the drain plug, if equipped.
7. Install the oil pan drain plug, if equipped. Tighten: Tighten the oil pan drain plug to 18 N.m (13 lb ft).
8. Lower the vehicle.
9. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

1. Remove the engine air cleaner. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L or to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls - 4.8L, 3.3L and 6.0L.
2. Remove the transmission fluid level indicator from the fluid fill tube.
3. Remove the bolt and the nut securing the transmission fluid fill tube to the engine.
4. Remove the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/exteriorinterior-trim/#interior-trim) in Interior Trim.
5. Remove the nut securing the transmission fluid fill tube to the transmission stud.
6. Remove the upper fill tube from the vehicle.
7. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
8. Support the vehicle with safety stands.
9. Remove any dirt from the transmission where the fluid fill tube enters the transmission case.
10. Remove the drain plug from the transmission. Drain the fluid into an approved container.
11. Remove the transmission fluid fill tube from the transmission. Pull the tube upward from the transmission.
12. Remove the transmission fill tube seal.
13. Clean the metal parts using solvent. Do not allow the solvent to enter the transmission.
14. Air dry the parts.

1. Install a new oil level indicator tube seal into the transmission case.
2. Install the bottom of oil level indicator tube into the seal.
3. Remove the safety stands.
4. Lower the vehicle.
5. Install the upper fill tube to the vehicle.
6. Install the bolt and the nut securing the oil level indicator tube brackets to the engine. Tighten: Tighten the bolt to 47 N.m (35 lb ft). Tighten the nut to 25 N.m (18 lb ft).
7. Install the nut securing the oil level indicator tube to the transmission stud. Tighten: Tighten the nut to 25 N.m (18 lb ft).
8. Install the air cleaner. Refer to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-43l-introduction) in Engine Controls - 4.3L or to or to «Air Cleaner Assembly Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/testing-diagnostics/#engine-control-system-48l-53l-60l-introduction) in Engine Controls - 4.8L, 3.3L and 6.0L.
9. Install the engine cover. Refer to «Engine Cover Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/exteriorinterior-trim/#interior-trim) in Interior Trim.
10. Fill the transmission fluid to the proper level. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Disconnect the input speed sensor (1) electrical connector.
3. Remove the input speed sensor bolt.
4. Remove the input speed sensor (1) and the bracket assembly from the case.
5. Inspect the vehicle speed sensor assembly (1) for any evidence of damage.

1. Lubricate the input speed sensor seal with automatic transmission fluid.
2. Install the input speed sensor (1) and the bracket assembly.
3. Install the bolt. Tighten: Tighten the bolt to 11 N.m (96 lb in).
4. Connect the input speed sensor electrical connector.
5. Lower the vehicle.

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Disconnect the output speed sensor (2) electrical connector.
3. Remove the output speed sensor bolt.
4. Remove the output speed sensor (2) and the bracket assembly from the case.
5. Inspect the output speed sensor assembly (2) for any evidence of damage.

1. Lubricate the output speed sensor seal with automatic transmission fluid.
2. Install the output speed sensor (2) and the bracket assembly.
3. Install the bolt. Tighten: Tighten the bolt to 11 N.m (96 lb in).
4. Connect the output speed sensor electrical connector.
5. Lower the vehicle.

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
3. Remove the park/neutral position switch. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
4. Remove the manual shaft nut and the pin.
5. Remove the detent lever and the actuator assembly.
6. Remove the bolts and the parking pawl bracket.
7. Remove the parking pawl return spring.
8. Use the modified screw extractor in order to remove the plug.
9. Remove the parking pawl shaft retainer, the shaft and the pawl.
10. Remove the manual shaft.
11. Remove the manual shaft seal.

1. Install the pawl shaft.
2. Install the parking pawl.
3. Install the plug using a 8 mm or (5/16 inch) rod with Loctite® or the equivalent.
4. Install the retainer.
5. Install the pawl return spring.
6. Install the detent lever to the actuator assembly.
7. Install actuator assembly over the parking pawl.
8. Install the manual shaft seal.
9. Lubricate the manual shaft with transmission oil and install the manual shaft into the case.
10. Install the nut on the shaft.
11. Install the roll pin.
12. Install the parking lock bracket with the two bolts. Tighten: Tighten the bolts to 24 N.m (18 lb ft).
13. Install the park/neutral position switch. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
14. Install the oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
15. Lower the vehicle.
16. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

J 36850 Transjel®

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the transmission oil pan and the filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
3. Remove the reverse boost valve bushing retainer ring (2).
4. Remove the following from the reverse boost valve cylinder: The reverse boost valve bushing The reverse boost valve The pressure regulator spring retainer The pressure regulator spring The pressure regulator valve The reverse boost valve bushing

1. Install the pressure regulator valve with J 36850 .
2. Pre-assemble the following parts: The reverse boost valve bushing A new reverse boost valve A new pressure regulator spring retainer The added isolator pressure regulator spring The pressure regulator spring
3. Install the pre-assembled parts into the pump bore.
4. Install the reverse boost valve bushing retainer ring while holding the reverse boost valve bushing in place. Ensure the retainer ring (2) is in the groove.
5. Install the transmission oil pan and the oil filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
6. Lower the vehicle.
7. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the transmission oil pan and the oil filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
3. Remove the valve bore plug retainer ring (1).
4. Remove the following parts: The valve bore plug The TCC valve The TCC valve spring

1. Install the following parts: The TCC valve spring The TCC valve The valve bore plug
2. Install the valve bore plug retainer ring (1).
3. Install the transmission oil pan and oil filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
4. Lower the vehicle.
5. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

J 25025 Guide Pins

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the control valve body assembly. Refer to «Valve Body and Pressure Switch Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement__valve-body-and-pressure-switch-replacement) .
3. Remove the 3rd and 4th clutch accumulator housing bolts (1).
4. Remove the 3rd and 4th clutch accumulator housing (8).
5. Remove the accumulator housing gasket (6). The accumulator housing gasket may be stuck to the spacer plate (5).
6. Remove the 3rd clutch accumulator piston spring (7).
7. Remove the 4th clutch accumulator piston spring (2).
8. Remove the control valve body spacer plate (5).
9. Remove the control valve assembly to spacer plate gasket (4) from the spacer plate (5).

Third and Fourth Clutch Accumulator Disassembly

1. Remove the 3rd clutch accumulator piston (2).
2. Remove the 3rd clutch accumulator piston seals (1, 3).
3. Remove the 4th clutch accumulator piston pin retainer ring (5).
4. Remove the 4th clutch accumulator piston (4) and pin (2) from the accumulator housing (1).
5. Remove the 4th clutch accumulator piston pin (2) from the accumulator housing (1).
6. Remove the 4th clutch accumulator piston seal (3) from the accumulator housing (1).

Third and Fourth Clutch Accumulator Assembly

1. Install the 3rd clutch accumulator piston inner (3) and outer (1) seals. Lubricate the 3rd clutch accumulator piston seals (1, 3) with DEXRON® III automatic transmission fluid.
2. Install the 3rd clutch accumulator piston (2).
3. Install the 4th clutch accumulator piston seal (3). Lubricate the 4th clutch accumulator piston seal (3) with DEXRON® III automatic transmission fluid.
4. Assemble the 4th clutch accumulator piston pin (2) with the 4th clutch accumulator piston (4).
5. Install the 4th clutch accumulator piston assembly into the accumulator housing (1).
6. Install the 4th clutch accumulator piston pin retainer ring (5) onto the 4th clutch accumulator piston pin (2).

1. Install the J 25025 into the control valve body bolt hole where the manual shaft detent roller and spring assembly is mounted.
2. Install the control valve body gasket (2) onto the accumulator housing (1).
3. Install the control valve body spacer plate (3) onto the valve body gasket (2).
4. Install the third and fourth clutch accumulator housing gasket (3).
5. Install the third clutch accumulator piston spring (1). This spring is the longer of the two springs.
6. Install the fourth clutch accumulator piston spring (4).
7. Install the third and fourth clutch accumulator housing assembly (5) onto the control valve body assembly (2).
8. Install the six accumulator housing bolts (6). Start the bolts finger tight and work towards the opposite end.
9. Tighten the accumulator housing bolts sequentially. Tighten: Tighten the accumulator housing bolts to 11 N.m (97 lb in).
10. Remove the J 25025 .
11. Install the control valve body assembly. Refer to «Valve Body and Pressure Switch Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement__valve-body-and-pressure-switch-replacement) .
12. Lower the vehicle.
13. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the transmission oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
3. Remove the rear servo assembly from the transmission case as follows: Cover bolts (6) Cover (5) Cover gasket (4) Bottom retaining clip (3) Servo piston (2) Outer ring oil seal (1) Inner ring oil seal (7) Accumulator piston (8) Piston seal (9) Washer (10) Servo spring (11) Servo spring retainer (12) Selective pin (13) Accumulator spring (14)

1. Install the rear servo assembly to the transmission case as follows: Accumulator spring (14) Selective pin (13) Servo spring retainer (12) Servo spring (11) Washer (10) Piston seal (9) Accumulator piston (8) Inner ring oil seal (7) Outer ring oil seal (1) Servo piston (2) Bottom retaining clip (3) Cover gasket (4) Cover (5) Cover Bolt (6)
2. Install the cover bolts (61). Tighten: Tighten the bolts to 24 N.m (18 lb ft).
3. Install the transmission oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
4. Lower the vehicle.
5. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

1. Pull the plastic cap back from the quick connect fitting and down along the cooler line about 5 cm (2 in).
2. Using a bent-tip screwdriver, pull on one of the open ends of the retaining ring in order to rotate the retaining ring around the quick connect fitting until the retaining ring is out of position and can be completely removed.
3. Remove the retaining ring from the quick connect fitting.
4. Discard the retaining ring.
5. Pull the cooler line straight out from the quick connect fitting.

1. Install a new retaining ring into the quick connect fitting using the following procedure
2. Hook one of the open ends of the retaining ring in one of the slots in the quick connect fitting.
3. Rotate the retaining ring around the fitting until the retaining ring is positioned with all three ears through the three slots on the fitting.
4. Do not install the new retaining ring onto the fitting by pushing the retaining ring.
5. Ensure that the three retaining ring ears are seen from inside the fitting and that the retaining ring moves freely in the fitting slots.
6. Install the cooler line into the quick connect fitting.
7. Insert the cooler line end into the quick connect fitting until a click is either heard or felt.
8. Do not use the plastic cap on the cooler line in order to install the cooler line into the fitting.
9. Pull back sharply on the cooler line in order to ensure that the cooler line is fastened into the quick connect fitting.
10. Position (snap) the plastic cap onto the fitting. Do not manually depress the retaining ring when installing the plastic cap onto the quick connect fitting.
11. Ensure that the plastic cap is fully seated against the fitting.
12. Ensure that no gap is present between the cap and the fitting.
13. Ensure that the yellow identification band on the tube is hidden within the quick connect fitting.
14. A hidden yellow identification band indicates proper joint seating.
15. Fill the transmission to the proper level with DEXRON® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l60-e4l65-e-troubleshooting__transmission-fluid-checking-procedure) .

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) .
2. Remove the oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
3. Remove the six forward servo cover bolts, cover, and gasket.
4. Remove the following parts: Forward servo piston pin (5) O-ring seal (4) Servo piston (3) Retainer (2) Piston spring (1)

1. Install the following parts: Piston spring (1) Retainer (2) Servo piston (3) O-ring seal (4) Forward servo piston pin (5)
2. Install the forward servo gasket, cover, and bolts. Tighten: Tighten the bolts to 24 N.m (18 lb ft).
3. Install the oil pan and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
4. Lower the vehicle.
5. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Support the vehicle with safety stands.
3. Remove the 2 oil cooler lines from the radiator.
4. If equipped with the auxiliary transmission oil cooler, remove the outlet pipe from the auxiliary cooler pipe.
5. Remove the 2 oil cooler lines from the transmission.
6. Remove the 2 oil cooler lines from the clips on the frame rail.
7. Pull the plastic cap back from the quick connect fitting and down along the cooler line about two inches.
8. Using a bent-tip screwdriver, pull on one of the open ends of the retaining ring in order to rotate the retaining ring around the quick connect fitting until the retaining ring is out of position and can be completely removed.
9. Remove the retaining ring from the quick connect fitting.
10. Discard the retaining ring.
11. Pull the cooler line straight out from the quick connect fitting.
12. Remove the retaining ring (E-clips) securing the cooler line to the quick connect in order to remove the remaining cooler lines from the remaining quick connect fittings.
13. Remove the cooler lines from the vehicle.
14. Lower the vehicle.

1. Raise the vehicle.
2. Install the transmission oil cooler line to the vehicle.
3. Install the new retaining ring (E-clip) into the quick connect fitting.
4. Install the 2 cooler lines to the radiator.
5. If equipped with the auxiliary oil cooler, install the inlet line to the radiator and the outlet to the auxiliary cooler line.
6. Install the 2 oil cooler lines to the transmission.
7. Hook one of the open ends of the retaining ring in one of the slots in the quick connect fitting.
8. Rotate the retaining ring around the fitting until the retaining ring is positioned with all three ears through the three slots on the fitting.
9. Do not install the new retaining ring onto the fitting by pushing the retaining ring down over the fitting.
10. Ensure that the three retaining ring ears are seen from inside the fitting and that the retaining ring moves freely in the fitting slots.
11. Install the new retaining ring (E-clip) into the remaining quick connect fittings.
12. Install the cooler line into the quick connect fitting.
13. Insert the cooler line end into the quick connect fitting until a click is either heard or felt.
14. Do not use the plastic cap on the cooler line in order to install the cooler line into the fitting.
15. Pull back sharply on the cooler line in order to ensure that the cooler line is fastened into the quick connect fitting.
16. Position (snap) the plastic cap onto the fitting. Do not manually depress the retaining ring when installing the plastic cap onto the quick connect fitting.
17. Ensure that the plastic cap is fully seated against the fitting.
18. Ensure that no gap is present between the cap and the fitting.
19. Ensure that the yellow identification band on the tube is hidden within the quick connect fitting. A hidden yellow identification band indicates proper joint seating.
20. Do not install the cooler line into the fitting incorrectly.
21. If you cannot position the plastic cap against the fitting, remove the retaining ring from the quick connect fitting per step 3 of the cooler line removal procedure. Check the retaining ring and the tube end in order to ensure neither is bent. Replace the cooler line or the retaining ring if necessary, and reinstall per Step 1 of the cooler line installation procedure.
22. Install the cooler line into the quick connect fitting again in order to install the remaining cooler lines into the remaining quick connect fittings.
23. Install the engine or transmission cooler lines to the frame.
24. Lower the vehicle.

1. Remove the grille assembly. Refer to «Grille Replacement (Uplevel)»(/chevrolet/chevy-express-g3500/1996-2012/remont/exteriorinterior-trim/#exterior-trim) or «Grille Replacement (Base)»(/chevrolet/chevy-express-g3500/1996-2012/remont/exteriorinterior-trim/#exterior-trim) .
2. Disconnect the 2 lines from the auxiliary cooler.
3. Remove the lines from the push clips on the auxiliary cooler mounting bracket.
4. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
5. Remove the lower bolts from the auxiliary cooler mounting bracket.
6. Lower the vehicle.
7. Remove the upper bolts.
8. Remove the auxiliary oil cooler from the vehicle.

1. Install the oil cooler into the vehicle.
2. Install the upper bolts into the oil cooler bracket. Tighten: Tighten the bolts to 10 N.m (89 lb in).
3. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
4. Install the lower bolts to the oil cooler bracket. Tighten: Tighten the bolts to 10 N.m (89 lb in).
5. Lower the vehicle.
6. Connect the oil cooler lines to the auxiliary oil cooler.
7. Attach the oil cooler lines to the push clips in the mounting bracket.
8. Reinstall the grille assembly. Refer to «Grille Replacement (Uplevel)»(/chevrolet/chevy-express-g3500/1996-2012/remont/exteriorinterior-trim/#exterior-trim) or «Grille Replacement (Base)»(/chevrolet/chevy-express-g3500/1996-2012/remont/exteriorinterior-trim/#exterior-trim) .

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Remove the two bolts securing the transmission heat shield to the cross member.
3. Remove the transmission heat shield from the cross member.

1. Install the transmission heat shield to the cross member.
2. Install the two bolts securing the transmission heat shield to the cross member. Tighten: Tighten the bolts to 17 N.m (13 lb ft).
3. Lower the vehicle.

1. Remove the vent hose clip.
2. Remove the vent hose from the transmission vent.

1. Install the vent hose to the transmission.
2. Install the vent hose to the clip.
3. Install the bolt and the clamp. Tighten: Tighten the bolt to 10 N.m (89 lb in).

1. J 43911 Selector Shaft Seal Remover
2. J 43909 Selector Shaft Seal Installer

1. Remove the Park/Neutral Position (PNP) Switch. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
2. Be sure that the jackscrew for J 43911 is backed off and will not interfere with installation of the removal tool. Slide the seal remover tool over the selector shaft (2) with the threaded end of the tool towards the seal.
3. Rotate the removal tool so that the threads on the end of the tool engage the steel shell (1) of the seal. Use a wrench to be sure that the removal tool is firmly attached to the seal shell.
4. Rotate the jackscrew in the clockwise direction to remove the seal from the bore. Discard the seal that was removed.

1. Carefully slide a new selector shaft seal (1) over the selector shaft (2) with the wide face of the steel case facing outward. Position the seal so that it is starting to enter the seal bore.
2. Obtain J 43909 and remove the inner sleeve so that the tool will slide over the selector shaft.
3. Slide the J 43909 into position so that the end of the tool contacts the seal being installed. Use a mallet to strike the J 43909 and drive the new seal into the seal bore until it is seated at the bottom of the bore.
4. Install the PNP Switch. Refer to «Park/Neutral Position Switch Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .

Valve Body and Pressure Switch Replacement

Tools Required

1. J 25025 Guide Pins
2. J 36850 Transjel®

1. Ensure that removal of the valve body is necessary before proceeding. IMPORTANT: The following components can be serviced without removing the valve body from the transmission: The 2-3 solenoid (1) The internal wiring harness (2) The 1-2 shift solenoid (3) The transmission fluid temperature sensor (4) The transmission fluid pressure manual valve position switch (5) The pressure control solenoid (6) The torque converter clutch pulse width modulation (TCC PWM) solenoid (7)
2. Remove the fluid level indicator.
3. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
4. Remove the oil pan, gasket, and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
5. Disconnect the internal wire harness from the transmission fluid pressure (TFP) manual valve position switch.
6. Remove the control valve body bolts (1) that retain the (TFP) manual valve position switch (2) to the control valve body.
7. Remove the TFP manual valve position switch.
8. Disconnect the internal wiring harness electrical connectors from the remaining valve body electrical components.
9. Remove the lube oil pipe bolt (6) and retainer (7).
10. Remove the lube oil pipe (5).
11. Remove the bolts and remove the manual shaft detent spring (3). IMPORTANT: Keep the control valve body level when lowering it from the vehicle. This will prevent the loss of checkballs located in the transmission case passages.
12. Remove the remaining control valve body bolts.
13. Carefully lower the valve body down from the transmission case. Use care not to drop the manual shaft valve.
14. Remove the control valve assembly (2) which includes the following: The accumulator housing assembly (1) The control valve assembly to the spacer plate gasket The spacer plate
15. Remove the manual valve (1) from the control valve body.
16. Inspect the manual valve for nicks and burrs.
17. Remove the spacer plate to case gasket (2) from the case. The gasket may stick to the spacer plate.
18. Remove the PWM screen (1) from the case passage.
19. Remove the manual 2-1 band servo assembly (1).
20. Remove the servo piston cushion spring (2).
21. Remove the manual 2-1 band servo piston pin retainer ring (4).
22. Remove the manual 2-1 band servo piston pin (1).
23. Remove the manual 2-1 band servo piston seal (2).
24. Remove the eight checkballs (nine checkballs for some models).

1. Install the 8 checkballs (9 checkballs for some models) into the control valve body. The checkball marked as number 2, is used on RCP, RDP, ZJP and ZLP models only To hold the checkballs in place, use the J 36850 .
2. Install the PWM screen into the control valve body.
3. Install a new manual 2-1 band servo piston seal (2) onto the manual 2-1 band servo piston (3).
4. Install the manual 2-1 band servo piston pin (1) into the manual 2-1 band servo piston (3).
5. Install the manual 2-1 band servo piston pin retainer ring (4).
6. Install the manual 2-1 band servo piston cushion spring (2).
7. Install the manual 2-1 band servo piston assembly (1).
8. Install the manual valve (1) into the control valve body.
9. To aid in alignment and assembly, install tool J 25025 .
10. Install the control valve body gasket (6).
11. Install the control valve body assembly (5). Attach the manual valve to the detent lever while installing the control valve body assembly.
12. Install the transmission fluid pressure manual valve position switch (2).
13. Install the transmission fluid pressure manual valve position switch bolts (1) finger tight.
14. Tighten the bolts in the order shown to 11 N.m (97 lb in).
15. Remove the J 25025 .
16. Install the manual shaft detent roller and spring assembly (3) and bolts.
17. Install the two wiring harness clips (1) and bolts (2).
18. Install the wiring harness clip (1) and bolts (2).
19. Install the lube oil pipe (5) with the short end into the control valve body.
20. Install the lube oil pipe retainer (7) and the bolt (6).
21. Install the control valve body bolts. Tighten: Tighten the bolts in the order shown to 11 N.m (97 lb in).
22. Install the remaining control valve body bolts. Tighten: Tighten the remaining bolts to 11 N.m (97 lb in).
23. Connect the internal wiring harness to the valve body electrical components.
24. Install the oil pan, gasket, and filter. Refer to «Automatic Transmission Fluid/Filter Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
25. Lower the vehicle.
26. Fill the transmission to the proper level using approved fluid.
27. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

Transmission Extension Housing Rear Oil Seal Replacement

Tools Required

1. J 38869 Rear Extension Seal Installer
2. J 6125-1B Slide Hammer Adapter. See «Special Tools and Equipment»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
3. J 23129 Universal Seal Remover. See «Special Tools and Equipment»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
4. J 36850 Transjel®. See «Special Tools and Equipment»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .

1. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Place a drain pan under the vehicle.
3. Remove the propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «Propeller Shaft Replacement - Two Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints__propeller-shaft-replacement-two-piece) in Propeller Shaft.
4. Using the J 6125-1B (1) and the J 23129 (2), remove the output shaft seal (3) from the extension housing (4). See «Special Tools and Equipment»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
5. Inspect the case extension housing for damage. Replace the extension housing if necessary. Refer to «Transmission Extension Housing Assembly Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .

1. Lubricate the inside diameter of the new seal with J 36850 . See «Special Tools and Equipment»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
2. Use the J 38869 (1) with a soft faced mallet to install the seal (2).
3. Install the seal (2) to the extension housing (3).
4. Install the propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «Propeller Shaft Replacement - Two Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints__propeller-shaft-replacement-two-piece) in Propeller Shaft.
5. Remove the drain pan and lower the vehicle.
6. Fill the transmission to the proper level with approved fluid.

1. Raise and suitably support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Support the transmission with a transmission jack.
3. Place a drain pan under the vehicle.
4. Remove the propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «Propeller Shaft Replacement - Two Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints__propeller-shaft-replacement-two-piece) in Propeller Shaft.
5. Remove the transmission support and the transmission mount. Refer to «Transmission Mount Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
6. Remove the case extension bolts (3).
7. Remove the case extension (1).
8. Remove and discard the case extension O ring seal (2).

1. Install a new case extension O ring seal (2).
2. Install the case extension (1). NOTE: Refer to Fastener Notice in Cautions and Notices.
3. Install the case extension bolts (3). Tighten: Tighten the case extension bolts (3) to 34 N.m (25 lb ft).
4. Install the transmission support and the transmission mount. Refer to «Transmission Mount Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
5. Install the propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «Propeller Shaft Replacement - Two Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints__propeller-shaft-replacement-two-piece) in Propeller Shaft.
6. Remove the drain pan and the transmission jack.
7. Lower the vehicle.
8. Fill the transmission to the proper level with Dexron® III transmission fluid. Refer to «Transmission Fluid Checking Procedure»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__transmission-fluid-checking-procedure) .

1. Raise and support the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
2. Support the transmission with a transmission jack.
3. Remove the transmission support. Refer to «Transmission Support Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) in Frame and Underbody.
4. Remove the transmission mount mounting bolts, for RWD vehicles.
5. Remove the transmission mount mounting bolts, for 4WD vehicles.
6. Remove the transmission mount from the vehicle.

1. Install the transmission mount to the vehicle.
2. Install the transmission mount mounting bolts, for 4WD vehicles. Tighten: Tighten the bolts to 50 N.m (37 lb ft).
3. Install the transmission mount mounting bolts, for RWD vehicles. Tighten: Tighten the bolts to 50 N.m (37 lb ft).
4. Install the transmission support. Refer to «Transmission Support Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) in Frame and Underbody.
5. Remove the transmission jack.
6. Lower the vehicle.

1. Disconnect the battery negative cable assembly from the battery negative terminal.
2. Raise the vehicle. Refer to «Lifting and Jacking the Vehicle»(/chevrolet/chevy-express-g3500/1996-2012/remont/hoistjack/#general-information__lifting-and-jacking-the-vehicle) in General Information.
3. Support the vehicle with safety stands.
4. If equipped with All Wheel Drive (AWD), remove the transfer case. Refer to «Transfer Case Assembly Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/transfer-case/#transfer-case-bw-4473-np3) in Driveline/Axle.
5. Disconnect the range selector cable from the transmission bracket and from the range selector lever.
6. Remove the rear propeller shaft. Refer to «Propeller Shaft Replacement - One Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints) or «Propeller Shaft Replacement - Two Piece»(/chevrolet/chevy-express-g3500/1996-2012/remont/driveshaft-universal-joints/#propeller-shaft-and-universal-joints__propeller-shaft-replacement-two-piece) in Driveline Axle.
7. Support the transmission with a transmission jack.
8. Remove the transmission support. Refer to «Transmission Support Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) in Frame and Underbody.
9. Remove the exhaust pipe from the exhaust manifolds and the muffler assembly from the exhaust pipe. Refer to «Catalytic Converter Replacement (4.3L)»(/chevrolet/chevy-express-g3500/1996-2012/remont/exhaust/#engine-exhaust-system) in Engine Exhaust.
10. Remove the starter motor. Refer to «Starter Motor Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-g3500/1996-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Starter Motor Replacement (4.3L)»(/chevrolet/chevy-express-g3500/1996-2012/remont/charging-system/#battery-charging-system-and-starting-system) in Engine Electrical.
11. Mark the flywheel and the torque converter alignment.
12. Remove the bolts that attach the torque converter to the engine flywheel.
13. Remove the transmission vent hose and the wiring harness from the transmission.
14. Remove the transmission fluid fill tube and the fill tube seal from the transmission. Refer to «Filler Tube and Seal Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement)
15. Plug the fluid fill tube opening in the transmission.
16. Disconnect the transmission oil cooler pipes from the transmission. Refer to «Transmission Fluid Cooler Hose/Pipe Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
17. Plug the transmission oil cooler pipe connectors in the transmission case.
18. Disconnect the wiring harness connectors from the transmission vehicle speed sensor and the park/neutral position switch.
19. Remove all vehicle harness wires, harness clips, tubes, brackets, and lines that may interfere with the removal of the transmission from the vehicle.
20. Remove the studs and the bolts securing the transmission to the engine.
21. Pull the transmission straight back.
22. Remove the transmission from the vehicle.
23. Inspect all the components for wear and damage.
24. Inspect all the seals and the fittings for signs of wear.
25. Inspect the torque converter for stripped or broken weld nuts.
26. Inspect the transmission case for cracks.
27. Perform the automatic transmission oil cooler flushing and flow test. Refer to «Automatic Transmission Oil Cooler Flushing and Flow Test (J 35944-A)»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__automatic-transmission-oil-cooler-flushing-and) or «Automatic Transmission Oil Cooler Flushing and Flow Test (J 45096)»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__automatic-transmission-oil-cooler-flushing-and) .

1. Support the transmission with a transmission jack.
2. Raise the transmission into place.
3. Slide the transmission straight onto the locating pins while lining up the marks on the flywheel and the torque converter.
4. Install the bolts that secure the transmission to the engine. Tighten: Tighten the studs and the bolts to 47 N.m (34 lb ft).
5. Install the bolts securing the torque converter to the engine flywheel. Tighten: First tighten all the bolts finger tight in order to insure proper converter seating. Tighten the bolts to 63 N.m (46 lb ft).
6. If equipped with All Wheel Drive (AWD), install the transfer case. Refer to «Transfer Case Assembly Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/transfer-case/#transfer-case-bw-4473-np3) in Driveline/Axle.
7. Install the wiring harness connectors to the vehicle speed sensor and the park neutral position switch.
8. Position and install all vehicle harness wires, harness clips, tubes, brackets, and lines that were removed or moved prior to the transmission removal.
9. Remove the two plugs from the transmission case cooling line connectors.
10. Install the transmission oil cooler pipes. Refer to «Transmission Fluid Cooler Hose/Pipe Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement) .
11. Install the transmission fluid fill tube and the fill tube seal. Refer to «Filler Tube and Seal Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-introduction-service-replacement)
12. Install the transmission vent hose and the wiring harness to the transmission.
13. Install the starter motor. Refer to «Starter Motor Replacement (4.8L, 5.3L, and 6.0L)»(/chevrolet/chevy-express-g3500/1996-2012/remont/charging-system/#battery-charging-system-and-starting-system) or «Starter Motor Replacement (4.3L)»(/chevrolet/chevy-express-g3500/1996-2012/remont/charging-system/#battery-charging-system-and-starting-system) in Engine Electrical.
14. Install the exhaust pipe to the exhaust manifolds and the muffler assembly to the exhaust pipe. Refer to «Catalytic Converter Replacement (4.3L)»(/chevrolet/chevy-express-g3500/1996-2012/remont/exhaust/#engine-exhaust-system) in Engine Exhaust. Install the transmission support. Refer to «Transmission Support Replacement»(/chevrolet/chevy-express-g3500/1996-2012/remont/frames-subframes-crossmembers/#frame-and-underbody) in Frame and Underbody.
15. Remove the transmission jack and the engine support stands.
16. Install the rear propeller shaft.
17. Install the transmission range select cable to the transmission range select lever and the bracket.
18. Flush the transmission oil cooler and the pipes whenever you remove the transmission for overhaul, or replacement of the torque converter, the pump, or the transmission case. Refer to «Automatic Transmission Oil Cooler Flushing and Flow Test (J 35944-A)»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__automatic-transmission-oil-cooler-flushing-and) or «Automatic Transmission Oil Cooler Flushing and Flow Test (J 45096)»(/chevrolet/chevy-express-g3500/1996-2012/remont/automatic-trans/#automatic-transmission-4l80-e4l85-e-troubleshooting__automatic-transmission-oil-cooler-flushing-and) .
19. Remove the safety stands.
20. Lower the vehicle.
21. Fill the transmission to the proper level with approved fluid.
22. Connect the battery negative cable assembly to the battery negative terminal. Tighten: Tighten the terminal bolt to 15 N.m (11 lb ft).

How to Use This Section

This section provides the following information

1. General diagnosis information on transmissions
2. Procedures for diagnosing the Hydra-Matic® transmission

When you diagnose any condition of the Hydra-Matic® transmission, begin with Diagnostic Starting Point. This procedure indicates the proper path of diagnosing the transmission by describing the basic checks. This procedure will then refer you to the locations of specific checks. After you have determined the cause of a condition, refer to Repair Instructions for repair procedures. If the faulty component is not serviceable without removing the transmission from the vehicle, refer to Unit Repair for repair information.

Basic Knowledge

Note. Do not, under any circumstances, attempt to diagnose a powertrain condition without basic knowledge of this powertrain. If you perform diagnostic procedures without this basic knowledge, you may incorrectly diagnose the condition or damage the powertrain components.

You must be familiar with some basic electronics in order to use this section of the service manual. You should also be able to use the following special tools

1. A Digital Multimeter (DMM)
2. A circuit tester
3. Jumper wires or leads
4. A line pressure gauge set

Diagnosis

Note. If you probe a wire with a sharp instrument and do not properly seal the wire afterward, the wire corrodes and an open circuit results.

Diagnostic test probes are now available that allow you to probe individual wires without leaving the wire open to the environment. These probe devices are inexpensive and easy to install, and they permanently seal the wire from corrosion.

Scheme 248

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 .

Transmission Adaptive Functions

The 4L80-E transmission uses a line pressure control system that has the ability to adapt line pressure to compensate for normal wear of the following parts

1. The clutch fiber plates
2. The springs and seals
3. The apply bands

This adaptive feature is similar to the fuel and idle control systems, where the PCM has the ability to learn and adjust for monitored system changes.

The PCM maintains information for the following transmission adaptive systems

1-2, 2-3, 3-4 Upshift Adapts - The PCM monitors the automatic transmission input shaft speed sensor (ISS) and the output speed sensor (OSS), to determine when the transmission has started, and completed an upshift. The PCM looks at the time from the beginning, until the completion of the upshift. If the time of the upshift was longer than a calibrated value, then the PCM will adjust the current to the transmission pressure control (PC) solenoid to increase line pressure for the next, same, upshift under identical conditions. If the time of the upshift was shorter than a calibrated value, then the PCM will adjust the current, to the transmission PC solenoid, to decrease line pressure for the next, same, upshift under identical conditions.

Steady State Adapts - Diesel only - The PCM monitors the automatic transmission input shaft speed sensor (ISS) and the output speed sensor (OSS) after a shift has occurred, to determine the amount of clutch slippage in the transmission. If to much slippage is detected, the PCM adjusts the current, to the transmission PC solenoid, to increase the line pressure and reduce clutch slip.

Clearing Transmission Adaptive Pressure (TAP)

Transmission adaptive pressure (TAP) information is displayed and may be reset using a scan tool. The adapt function is a feature of the PCM that either adds or subtracts line pressure from a calibrated base line pressure in order to compensate for normal transmission wear. The TAP information is divided into 13 units, called cells. The cells are numbered 4 through 16. Each cell represents a given torque range. TAP cell 4 is the lowest adaptable torque range and TAP cell 16 is the highest adaptable torque range. It is normal for TAP cell values to display zero or negative numbers. This indicates that the PCM has adjusted line pressure at or below the calibrated base line pressure.

Updating TAP information is a learning function of the PCM designed to maintain acceptable shift times. It is not recommended that TAP information be reset unless one of the following repairs has been made

1. Transmission overhaul or replacement
2. Repair or replacement of an apply or release component (clutch, band, piston, servo)
3. Repair or replacement of a component or assembly which directly affects line pressure

Resetting the TAP values using a scan tool will erase all learned values in all cells. As a result, the PCM will need to relearn TAP values. Transmission performance may be affected as new TAPs are learned. Learning can only take place when the PCM has determined that an acceptable shift has occurred. The PCM must also relearn TAP values if it is replaced.

Scheme 249

The powertrain control module (PCM) energizes the torque converter clutch pulse width modulated (TCC PWM) solenoid valve, which is located on the transmission valve body. The TCC PWM solenoid valve acts on the TCC apply valve in order to control the torque converter clutch application.

The TCC PWM solenoid valve is pulse width modulated by the PCM. This means that the PCM pulses the solenoid so that the hydraulic pressure against the torque converter clutch modulates. This modulated pressure allows the TCC to slip slightly, thus keeping the TCC balanced just at the point of engagement.

One diagnostic code is associated with the TCC PWM solenoid valve Code P2761, TCC solenoid circuit - electrical, detects a fault in the TCC circuit. While Code P2761 is set, both fourth gear in hot mode and the TCC are inhibited. Shift adapts do not update and the MIL illuminates. Recovery can occur on the next ignition cycle.

Scheme 250

The pressure control (PC) solenoid valve is attached to the valve body. The valve controls line pressure by moving a pressure regulator valve against spring pressure. The PC solenoid valve takes the place of the throttle valve or the vacuum modulator, which was used on past model transmissions.

The PCM varies line pressure based on engine load. Engine load is calculated from various inputs, especially the throttle position (TP) sensor switch. Line pressure is actually varied by changing the amperage applied to the PC solenoid valve from 0 amps, high pressure, to 1.1 amps, low pressure. The PC solenoid valve current is periodically pulsed in order to prevent contamination from sticking the pressure regulator valve.

One diagnostic code is associated with the PC solenoid valve. Code P0748 sets when the PCM detects a difference of 0.16 amp or greater between the amperage commanded and actual amperage. While the code is set, the PC solenoid valve turns OFF. Recovery can occur after the next ignition cycle. Code P0748 does not sense a hydraulic condition, such as a stuck valve.

Scheme 251

The 1-2 shift solenoid (SS) valve is a normally open exhaust valve that is attached to the valve body. The PCM controls the solenoid by grounding the solenoid through an internal quad driver. The 1-2 SS valve is ON in FIRST and FOURTH gear. When commanded ON, the 1-2 SS valve redirects fluid to act on the 1-2 shift valve.

There are two PCM related diagnostic trouble codes (DTCs) associated with the 1-2 SS valve: P0751 and P0753.

The PCM monitors the 1-2 SS circuit for an open or short to ground condition. If the PCM detects an open or short to ground condition, then DTC P0753 sets. If the PCM detects an incorrect gear ratio, then DTC P0751 sets. When DTC P0753 or P0751 sets, the PCM commands maximum line pressure, freezes shift adapts from being updated, and inhibits 3-2 downshifts.

Scheme 252

The 2-3 shift solenoid (SS) valve is a normally open exhaust valve that is attached to the valve body. The PCM controls the solenoid by grounding the solenoid through an internal quad driver. The 2-3 SS valve is ON in THIRD and FOURTH gear. When commanded ON, the 2-3 SS valve redirects fluid to act on the 2-3 shift valve.

There are two PCM related diagnostic trouble codes (DTCs) associated with the 2-3 SS valve: P0756 and P0758.

The PCM monitors the 2-3 SS circuit for an open or short to ground condition. If the PCM detects an open or short to ground condition, then DTC P0758 sets. If the PCM detects an incorrect gear ratio, then DTC P0756 sets. When DTC P0758 or P0756 sets, the PCM commands maximum line pressure, freezes shift adapts from being updated, and inhibits 3-2 downshifts.

Scheme 253

The automatic transmission fluid pressure (TFP) manual valve position switch assembly is a gear range sensing device used by the PCM in order to sense which gear range has been selected by the vehicle operator. The TFP manual valve position switch assembly is located on the valve body, and consists of five pressure switches combined into one unit. The PCM applies system voltage to the TFP manual valve position switch assembly on three separate wires. These three circuits are either grounded or open, depending on which gear range has been selected, and on which combination of the five switches gave pressure applied to them.

When the vehicle is in PARK, with the key ON and the engine OFF, the normal state of the TFP manual valve position switch assembly will be DRIVE 2. When the key is ON and the engine is running, the normal state of the TFP manual valve position switch assembly is in PARK/NEUTRAL.

There are two possible combinations of the switches within the pressure switch manifold that do not represent an actual gear range. If the PCM detects either of these combinations, then a diagnostic trouble code (DTC) sets.

The PCM TFP DTC P1810 sets when the TFP switch indicates the following

1. An illegal gear range
2. DRIVE4, DRIVE2 or REVERSE position before and after start-up
3. PARK/NEUTRAL with a ratio greater than 1.05
4. REVERSE with ratio indicating outside of REVERSE
5. DRIVE4, DRIVE3, DRIVE2 or DRIVE1 with ratio indicating REVERSE

While DTC P1810 is present, the PCM assumes DRIVE4 for shift pattern, sets line pressure to maximum, freezes shift adapts, and forces TCC ON with 4th gear commanded.

Oil Pressure and Circuit Combination Table

Scheme 254

Both of the automatic transmission input shaft speed (AT ISS) and the automatic transmission output shaft speed (AT OSS) sensors are magnetic induction sensors. The input and the output sensors are accessible from the left hand side of the transmission. The AT ISS sensor is located just forward of center and the AT OSS sensor is located near the rear. A voltage signal is induced in the AT ISS sensor by serrations, which are cut in the outside diameter of the forward clutch housing. Voltage is induced in the output sensor by gear teeth, which are pressed on the outside diameter of the rear carrier assembly.

Scheme 255

The PCM uses speed information from these sensors in order to determine the following

1. Whether the engine is running
2. Vehicle speed
3. Calculation of the gear ratio
4. Calculation of TCC slip
5. Calculation of turbine speed

Code P0502 and P0503 set if a fault exists in the AT OSS sensor circuit, and the PCM calculates a default value using the AT ISS sensor values. As long as the fault remains, and the code is set, the PCM also commands maximum line pressure, freeze shift adapts, and the MIL illuminates. If the fault is removed, normal operation resumes after the next ignition cycle.

Scheme 256

The automatic transmission fluid temperature (TFT) sensor assembly is a thermistor which is mounted in the wiring harness assembly. Low transmission temperature produces high resistance, while high temperature produces low resistance. The powertrain control module (PCM) supplies a 5-volt signal to the TFT sensor assembly through an internal resistor. Then the PCM measures the voltage drop in the circuit. Voltage is high when the transmission is cold and low when the transmission is hot.

The PCM uses the TFT sensor assembly in order to regulate torque converter clutch apply, as well as shift quality.

DTCs P0711, P0712 and P0713 indicate a fault in the TFT Sensor Assembly circuit. After the vehicle has been started, transmission temperature should rise steadily and stabilize between 90-115° C (194-239° F), depending on load. All 3 DTCs cause the PCM to use a default value of 140° C (284° F), thus reacting as if the transmission were hot in either case. When DTCs P0711, P0712 or P0713 are set, the PCM freezes the shift adapts from being updated, and the malfunction indicator lamp (MIL) illuminates. Some driveability symptoms will be noticed, especially when cold.

Scheme 257

The transmission range (TR) switch is part of the park/neutral position (PNP) and backup lamp switch assembly, which is externally mounted on the transmission manual shaft. The TR switch contains four internal switches that indicate the transmission gear range selector lever position. The powertrain control module (PCM) supplies ignition voltage to each switch circuit. As the gear range selector lever is moved, the state of each switch may change, causing the circuit to open or close. An open circuit or switch indicates a high voltage signal. A closed circuit or switch indicates a low voltage signal. The PCM detects the selected gear range by deciphering the combination of the voltage signals. The PCM compares the actual voltage combination of the switch signals to a TR switch combination chart stored in memory.

Scheme 258

The transmission electrical connector is an important part of the transmission operating system. Any interference with the electrical connection can cause the transmission to set diagnostic trouble codes or affect proper operation.

The following items can affect the electrical connection

1. Bent pins in the connector from rough handling during connection and disconnection
2. Wires backing away from the pins or coming uncrimped, in either the internal or the external wiring harness
3. Dirt contamination entering the connector when disconnected
4. Pins in the internal wiring connector backing out of the connector or pushed out of the connector during reconnection
5. Transmission fluid leaking into the connector, wicking up into the external wiring harness and degrading the wire insulation
6. Moisture intrusion in the connector
7. Low pin retention in the external connector from excessive connection and disconnection of the wiring connector assembly
8. Pin corrosion from contamination
9. Damaged connector assembly

Remember the following points

1. In order to remove the connector, squeeze the two tabs toward each other and pull straight up without pulling by the wires.
2. Limit twisting or wiggling the connector during removal. Bent pins can occur.
3. Do not pry the connector off with a screwdriver or other tool.
4. Visually inspect the seals to ensure that they are not damaged during handling.
5. In order to reinstall the external wiring connector, first orient the pins by lining up the arrows on each half of the connector. Push the connector straight down into the transmission without twisting or angling the mating parts.
6. The connector should click into place with a positive feel and/or noise.
7. Whenever the transmission external wiring connector is disconnected from the internal harness and the engine is operating, DTCs will set. Clear these DTCs after reconnecting the external connector.

Special Tools

Special Tools Illustration Tool Number/Description Scan Tool J 6125-1B Slide Hammer Adapter J 6125-B Slide Hammers J 21366 Converter Holding Strap J 21867 Pressure Gage J 23129 Universal Seal Remover J 25025 Guide Pins J 25025-5 Dial Indicator Mounting Post - M6x1.00 J 35616-B GM Terminal Test Kit J 35944-A Transmission Oil Cooler and Line Flusher J 35944-22 Transmission Oil Cooler Flushing Fluid J 35944-200 Cooler Flushing Adapter J 36850 Transjel Lubricant J 39200 Digital Multimeter (DMM) J 41364-A Park/Neutral Switch Aligner J 41505 Rear Lubricant Seal Installer J 43909 Selector Shaft Seal Installer J 43911 Selector Shaft Seal Remover J 44152 Jumper Harness (20 pins) J 44246 Solenoid Testing Kit J 45096 Transmission Oil Cooling System Flush and Flow Test Tool

Scheme 259

Scheme 260

Scheme 261

Scheme 262

Scheme 263

Scheme 264

Scheme 265

Scheme 266

Scheme 267

Scheme 268

Scheme 269

See also:
• Transmission Fluid Temperature (TFT) Sensor Specifications
• Knee Bolster Replacement - Left
• Lifting and Jacking the Vehicle
• Automatic Transmission Range Selector Cable Adjustment
• Automatic Transmission Range Selector Cable Replacement
• Transmission Fluid Checking Procedure
• Air Cleaner Assembly Replacement
• Air Cleaner Assembly Replacement
• Engine Cover Replacement
• Fastener Notice
• Transmission Fluid Checking Procedure
• Grille Replacement (Uplevel)
• Propeller Shaft Replacement - One Piece
• Propeller Shaft Replacement - Two Piece
• Transmission Support Replacement
• Battery Disconnect Caution
• Transfer Case Assembly Replacement
• Catalytic Converter Replacement (4.3L)
• Starter Motor Replacement (4.8L, 5.3L, and 6.0L)
• Automatic Transmission Oil Cooler Flushing and Flow Test (J 35944-A)
• Automatic Transmission Fluid/Filter Replacement
• Valve Body and Pressure Switch Replacement