Automatic Transaxle Overhaul & Testing - 4T80-E: Other Oldsmobile Aurora I

ON-VEHICLE SERVICE

The following components can be serviced without removing transaxle from vehicle

1. Case Side Cover Pan.
2. Converter-To-Flexplate Bolts.
3. Cooler Lines.
4. Drive Axles.
5. Final Drive Assembly.
6. Fluid Level Indicator.
7. Reverse Servo.
8. Scavenger Oil Scoop.
9. Manual Control Cable.
10. Output Shaft.
11. Solenoids "A" & "B".
12. Transaxle Input Speed Sensor.
13. Transaxle Temperature Switch.
14. Transaxle Pan.
15. Transaxle Filter.
16. Valve Body
17. Vehicle Speed Sensor.
18. Transaxle Wiring Harness.
19. 4th Servo.
20. 1-2, 3-4, Forward & Reverse Accumulator Assemblies.
21. Oil Pressure Switch Assembly.

VALVE BODY

See SIDE COVER, OIL PUMP & LOWER VALVE BODY under TRANSAXLE DISASSEMBLY.

DRIVE AXLE SHAFTS

See appropriate AXLE SHAFTS - FRONT article in the AXLE SHAFTS & TRANSFER CASES section.

QUICK CHECK

1. Check level and condition of transaxle fluid. Check PCM memory for stored codes. See «AUTO TRANS DIAGNOSIS - HYDRA-MATIC 4T80-E CONTROLS - 1995»(ref-56014) article or «AUTO TRANS DIAGNOSIS - HYDRA-MATIC 4T80-E CONTROLS - 1996»(ref-56015) article. If no codes are present, go to next step. If codes are present, diagnose and repair all PCM-related codes. Clear PCM code memory.
2. Perform road test. See «ROAD TEST»(ref-25525-S06646726932001011700000) under TESTING. Enter PCM data mode to monitor throttle angle. See appropriate 4T80-E ELECTRONIC CONTROLS article. During road test, record shift points. If shift point timing or shifting is incorrect, go to appropriate 4T80-E ELECTRONIC CONTROLS article.
3. If shift(s) is too harsh or too soft, see «HYDRAULIC PRESSURE TESTS»(ref-25525-S30180022112001011700000) under TESTING.
4. For specific complaints, see appropriate condition(s) listed under «SYMPTOMS»(ref-25525-S07230896742001011700000) in TROUBLE SHOOTING.

Oil Out Of Vent Or Foaming

Transaxle overfilled. Oil contaminated with antifreeze or engine overheating. Oil filter "O" ring damaged or missing. Scavenger oil pump screens blocked.

High Or Low Line Pressure

Incorrect oil level. Scavenge, primary or secondary oil pump assembly seals or gears damaged. Pressure regulator valve spring damaged or pressure regulator valve nicked, scored or seized. Pressure relief valve spring damaged or ball missing. Problem with transaxle pressure control solenoid oil feed or valve stuck. Pressure switch assembly loose. Check balls missing in control valve body. Pump or case cover leaking (bolts loose). Actuator feed limit valve stuck open.

Delayed Engagement

Low fluid level. Pressure regulator valve stuck in bore. Faulty pressure switch assembly, throttle position switch or vehicle speed sensor.

No Drive In "D"

1. Low oil level or pressure. Faulty torque converter. Manual linkage misadjusted or disconnected. Manual valve stuck. Blocked valve body channels or spacer plate. Damaged oil pump drive shaft or pump assemblies. Torque converter stator roller clutch damaged. Drive link assembly damaged, drive link chain broken or sprockets and bearings damaged.
2. Forward clutch assembly clutch plates burned, clutch plates missing, check ball capsule leaking or missing. Forward piston seals cut or damaged, or shaft feed passages blocked. Damaged or incorrectly assembled forward roller sprag or sun gear assembly.
3. Output shaft damaged or drive axles incorrectly assembled into differential. damaged or loose channel plates. Parking pawl spring broken. Damaged final drive assembly or final drive sun gear, side gears, pinion gears or internal ring gear.

Slips In "R"

Low fluid level. Low line pressure. Oil pump assemblies seals or gears damaged. Damaged reverse clutch assembly or leaking servo piston seal. Oil filter screen plugged. Leaking or damaged lo/reverse band servo seals. Damaged lo/reverse band.

Scheme 56

4T80-E GEAR RATIOS

No 1st Gear

Misadjusted manual valve. Damaged lo roller clutch, forward sprag or forward clutch assembly. Leaking oil transfer sleeve. Check for codes P016, P029 and P094. Check solenoid circuits "A" and "B" for loose, open or shorted wires. Check PCM for loose grounds, loose or corroded connections. Leaking 3rd clutch housing check ball. Broken splines at 3rd clutch housing or forward clutch splined shaft.

No 1st Gear (In "2", "3", Or "D")

Missing check ball No. 6 or inoperative coast clutch. Damaged lo/reverse servo apply pin. Stuck 1-2 shift valve. Damaged or broken coast clutch splined shaft or broken support studs. Damaged or worn lo roller clutch or forward clutch piston. Leaking support housing seal rings. Forward sprag damaged. Check for DTC 94. Problem with solenoid circuit "A".

No 2nd Gear (In "2" Or "3")

Solenoid "A" stuck on. Dirt in solenoid, PCM signal to solenoid "A" grounded or signal return wire shorted to ground. Stuck 1-2 shift valve. Damaged 2nd clutch housing seals, piston or piston check ball. Burned 2nd clutch housing clutches. Mispositioned rollers or broken springs on 2nd sprag.

No 3rd Gear (In "3")

Check for codes P019, P094 or P117. Solenoid "A" or "B" stuck. Dirt in solenoid, PCM signal to solenoid "B" grounded or signal return wire shorted to ground. Leaking or missing 3rd clutch check ball. Damaged 3rd clutch housing seals, piston or piston check ball. Burned 3rd clutch housing clutches. Exhaust valve cup plug or valve improperly installed in driven sprocket support.

No 4th Gear

Check for code P094. Failed "A" solenoid ("A" solenoid off). Dirt in filter, PCM not grounded, leaking "O" ring, no supply voltage to "A" solenoid or wire disconnected. Burned or damaged 4th band. Damaged 4th band servo assembly. Misassembled 3-4 shift valve bore plug.

3rd & 4th Gear Only

Check for code P0117. Solenoid "B" stuck. Dirt in solenoid, PCM signal to solenoid "B" grounded or signal return wire shorted to ground.

No Reverse

1. Oil pressure low. Reverse servo incorrectly assembled, piston or seal damaged or apply pin incorrect. Damaged oil pump drive shaft or oil pump assemblies. Drive link assembly damaged or drive link chain broken. Burned, damaged or mispositioned reverse band. Reverse clutch assembly clutch plates burned, clutch plates missing or check ball capsule leaking or missing.
2. Reverse piston seals cut or damaged, or shaft feed passages blocked. Reverse carrier shell splines damaged. Parking pawl spring broken. Damaged final drive assembly or final drive sun gear, side gears, pinion gears or internal ring gear.

Vehicle Moves In Park

Manual linkage damaged or disconnected. Broken final drive park pawl spring, park pawl or park pawl gear in final drive internal gear assembly. Park actuator spring damaged.

Vehicle Moves In Neutral

Manual linkage damaged or disconnected. Disconnected shift linkage. Jammed forward clutch plates, piston assembly or blocked oil feed hole. Mispositioned sprocket support hub.

Harsh Neutral-To-Drive Engagement

Engine idle too high. Missing final drive internal gear snap ring. Actuator feed limit valve stuck open.

Vehicle Starts In 2nd Gear

Check for codes P016, P029 and P094. Failed "A" solenoid ("A" solenoid off). Dirt in filter, PCM not grounded, leaking "O" ring, no supply voltage to "A" solenoid or wire disconnected. Leaking or damaged pressure control solenoid. Missing check ball in driven sprocket support (high line pressure starts only).

Soft Shifts

Line pressure too low. Pressure control solenoid stuck on. Check for code P028. Leaking pressure switch assembly. Incorrect PROM.

Erratic Shifts

Leaking or damaged "O" rings at "A" or "B" solenoids.

No Engine Breaking

Misaligned oil transfer sleeve. Broken or slipping drive chain. Damaged sprockets or drive splines.

No Overrun Breaking In "3"

Oil level too low. Burned or damaged coast clutch assembly. Damaged or cracked forward clutch housing. Stuck 3-4 shift valve. Check for trouble code P094. Stuck "A" solenoid or dirt in filter.

No Overrun Breaking In "2"

Stuck, broken or burned 4th band. Damaged 4th band servo assembly. Burned or damaged coast clutch assembly. Damaged or missing coast clutch support seal rings. Check for code P028. Pressure switch assembly not working.

No Engine Breaking In "1"

Check for code P028. Pressure switch assembly not working. Burned or damaged coast clutch assembly. Damaged or missing coast clutch support check ball. Stuck, broken or burned lo/reverse band. Damaged lo/reverse band servo assembly. Missing No. 6 check ball.

No TCC

Verify proper PCM operation and vehicle wiring. Check for possible codes P016, P029, P039, P088, P090 or P117. Check the following solenoids and switches for faulty operation, dirt or binding: TCC solenoid, brake switch, PRNDL ("P"/"N" switch) and coolant temperature sensor. Also check the same solenoid and switch circuits for open or shorted wires between voltage supply or PCM. Converter clutch shift valve of control valve assembly stuck. Converter clutch apply valve stuck. Solenoid "O" ring leaking or screen blocked. Turbine shaft seals damaged. Blocked oil pressure screen. Damaged or missing TCC "O" ring.

Converter Clutch Does Not Release

Check for code P039. TCC solenoid stuck on. TCC solenoid does not exhaust. Control valve assembly converter clutch apply valve stuck open. Turbine shaft splines damaged.

Converter Ballooning

Stuck converter feed valve.

Converter Clutch Apply With Cold Engine

Check for code P059. Transaxle temperature sensor shorted.

Converter Clutch Apply Too Soft

Fluid level too low. Converter clutch feed valve stuck. Turbine shaft seals damaged or missing. Faulty TCC solenoid. Seals damaged or missing. Defective converter clutch.

CLUTCH & BAND APPLICATION CHART (4T80-E)

Gear Selector Position "D" (Overdrive)

1. Enter PCM data mode to monitor throttle angle. See 4T80-E ELECTRONIC CONTROLS article. With gear selector in "D" (overdrive) position, steadily increase throttle pressure to accelerate vehicle. Note shift speed engagement points in 2nd gear, 3rd gear and overdrive gear. Use chart as a reference for proper shift speeds. (Scheme 57)- (Scheme 62). Also note Torque Converter Clutch (TCC) engagement point while in 3rd gear or Overdrive. NOTE: Ensure TCC engages in 3rd gear or overdrive during the following steps. If testing a Cadillac model and engagement point is hard to feel, use climate control panel to indicate TCC engagement and release points. See appropriate article in the ENGINE PERFORMANCE section: For 1995 vehicles, see «BASIC DIAGNOSTIC PROCEDURES»(ref-19979). For 1996 vehicles, see «BASIC DIAGNOSTIC PROCEDURES»(ref-20277).
2. At vehicle speeds of 40-50 MPH, quickly depress accelerator to half-open position (part throttle detent downshift). TCC should release, and transaxle should immediately downshift to 3rd gear. DEFOG on display changes from ON to OFF.
3. At vehicle speeds of 40-50 MPH, quickly depress accelerator to wide open position (full throttle detent downshift). TCC should release, and transaxle should immediately downshift to 2nd gear. DEFOG and ECON on display changes from on to off.
4. At vehicle speeds of 40-55 MPH, release accelerator pedal while moving gear selector to the "3" (third gear) position. The TCC should release, transaxle should downshift into 3rd gear.
5. Move gear selector to the "D" (overdrive) position, and accelerate to 40-45 MPH. Release accelerator pedal while moving gear selector to the "2" (2nd gear) position. The TCC should release, transaxle should downshift to 2nd gear immediately, and engine braking should slow vehicle.
6. Move gear selector to the "D" (overdrive) position, and accelerate to 30 MPH. Release accelerator pedal while moving gear selector to "1" (1st gear) position. TCC should release, transaxle should downshift to 1st gear and engine braking should slow vehicle.
7. With gear selector in the "D" (overdrive) position, accelerate vehicle to overdrive gear with TCC applied. Release accelerator pedal, and lightly apply brakes. The TCC should release. Note speeds at which vehicle downshifts. (Scheme 57)- (Scheme 62)

Scheme 57

Scheme 58

Scheme 59

Scheme 60

Scheme 61

Scheme 62

Gear Selector Position "3" (3rd Gear)

With vehicle stopped, move gear selector to "3" (3rd gear) position and steadily increase throttle pressure to accelerate vehicle. Note speeds at which vehicle goes into 2nd and 3rd gears. (Scheme 57)- (Scheme 62). Also note when TCC engages while in 3rd gear.

Gear Selector Position "2" (2nd Gear)

With vehicle stopped, move gear selector to the "2" (2nd gear) position. Accelerate vehicle and note speed at which vehicle shifts from 1st gear to 2nd gear. Accelerate vehicle to 25 MPH. Transaxle should not shift into 3rd gear, and TCC should not engage.

Gear Selector Position "1" (1st Gear)

With vehicle stopped, move gear selector to the "1" (1st gear) position. Accelerate vehicle to 15 MPH. Transaxle should not upshift, and TCC should not engage.

PCM DATA

Enter the following modes on climate control panel, if equipped and watch operation of sensors and transaxle. See ELECTRONIC SELF-DIAGNOSTICS & ELECTRONIC TESTING . Repeat the same test steps as during road test. See ROAD TEST under TESTING.

PD74 "A" Current

Line pressure should be low with over 1 amp current. Line pressure should be high with less than 1 amp current.

PD72 Turbine

Signal should be close to engine RPM.

PD73 Slip Speed

When TCC is release, numbers around 100 should be displayed. With TCC applied, numbers around 10 should be displayed.

PD76 Ratio

Should display transaxle ratios while in specific gear range (1st - 2.96, 2nd - 1.63, 3rd - 1.00, 4th - .68, "R" - 2.13).

PD77 Transaxle Temperature

Displays transaxle temperature in degrees centigrade.

PD82 Shift Time

Displays shift time. Shift time is usually about .25 second (except for first gear).

HYDRAULIC PRESSURE TESTS

Before performing hydraulic pressure tests, check fluid level and condition. Check manual control linkages for correct adjustment. Connect oil pressure gauge to line pressure test port. (Scheme 63)

Note. Hydraulic pressure is controlled by pump output and regulated by transaxle pressure control solenoid. Line pressure is boosted to 90-300 psi (6.2-20.7 kg/cm 2 ) in "R" position. Line pressure should increase when PCM commands less duty cycle (less current) to transaxle pressure control solenoid.

1. Enter PCM data mode to monitor throttle angle. See appropriate AUTO TRANS DIAGNOSIS - 4T80-E ELECTRONIC CONTROLS article. Check for stored trouble code P076. Repair vehicle as necessary.
2. Start engine and set parking brake. Select PCM OUTPUT OVERRIDE level on display panel. Access transaxle pressure control solenoid override (PS20). Increase PCM pressure signal to transaxle pressure control solenoid. Record line pressure readings.
3. Line pressure should gradually increase after each increase in command signal. Line pressure should be 50 psi (3.4 kg/cm 2 ) at zero percent command and about 240 psi (16.5 kg/cm 2 ) at 100 percent command. (Scheme 64) If recorded pressure is incorrect, see «HIGH OR LOW LINE PRESSURE»(ref-25525-S16052060112001011700000) under TROUBLE SHOOTING.

Scheme 63

Scheme 64

INPUT SHAFT END PLAY CHECK

Install Input Shaft End Play Fixture (J-39686) to front side of transaxle. Ensure "J" tab on fixture rests on input shaft. Mount Dial Indicator Post (J-25025-7A) and Dial Gauge (J-8001-3) to check end play. Push down on handle to raise input shaft. End play should be.004-.034" (.10-.85 mm). (Scheme 65) Record this measurement for reassembly.

Scheme 65

SIDE COVER, OIL PUMP & UPPER VALVE BODY

1. Remove side cover, filter and seals. Disconnect wiring harness from transaxle temperature sensor, transaxle pressure control and TCC solenoid and case connector. Remove wiring harness.
2. Remove oil pump assembly cover bolts and remove pump assemblies. Remove upper valve body and separate gasket and spacer plate.
3. Remove 2 check balls between spacer plate and transaxle case cover. Remove transaxle case cover and gaskets from transaxle case.

FORWARD & COAST CLUTCH HOUSING

1. Remove snap ring from forward/coast clutch housing. Remove backing plate, forward clutch, Belleville, coast clutch and apply plates from housing. Compress spring retainer and remove snap ring.
2. Remove coast piston, apply ring, forward clutch piston and seals. see scheme 20 Inspect clutches for wear and piston for cracks or damaged check ball.

LO/REVERSE SERVO & 4TH SERVO

For lo/reverse servo information, see VALVE BODIES under COMPONENT DISASSEMBLY & REASSEMBLY. see scheme 27 For 4th servo information, see CASE ASSEMBLY under TRANSAXLE DISASSEMBLY.