Transmission shifting

ARCTICPANDA

MEMBER
1999 SATURN SL1
1.9L
4 CYL
2WD
AUTOMATIC
137,295 MILES

When I first turn the car on, when I go from park to reverse it is a very hard clunk and no power. If I go to any other gear it also has no power and the car will not move. Occasionally if I restart the car and then go back into reverse or drive it will go in perfectly and then I can drive the vehicle around and it will have zero problems until I turn it off and restart it again. When it does go into the gears fine it shifts perfectly with no noise, smell, or hard shifts. Bought a few days ago from a dealer and they said it only had the issue once the vehicle was warmed up from driving so it never had issues in the morning. I checked the shift solenoids which were good and I made sure the fluid was at the proper level and not bad.

1 Reply

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

Hi and thanks for using 2CarPros. Com.

Based on your description, it sounds like an issue with transmission line pressure. This transmission has a pressure regulator valve which controls how much pressure is sent to the clutches/clutch packs. The pressure regulator valve controls line pressure to provide the correct pressure to apply clutches, supply lube and converter feed.

Here are the directions that require some special tooling to complete the line pressure test. Pictures 2 and 3 correlate with these directions.

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1999 Saturn SL1 L4-1.9L SOHC VIN 8
Line Pressure Test
Vehicle Transmission and Drivetrain Automatic Transmission/Transaxle Testing and Inspection Component Tests and General Diagnostics MP6/MP7 Saturn Automatic Transaxle Line Pressure Test
LINE PRESSURE TEST
1. Run engine to bring transaxle to running temperature of 70°C (158°F).
2. Turn engine off.
3. Remove transaxle fluid temperature sensor and install pressure gauge.
4. Reinstall temperature sensor in wire harness.
5. Connect the Scan tool.
6. Key On engine Off. On first menu selection, select "Special Test."
7. Select Line Pressure.
8. Transaxle in Park.
9. Scan tool will prompt you to start engine.
10. Select Run and the test will begin. The test will set engine speed to 1500 rpm and command line pressure up in steps from 396 - 1518 kPa (57 - 220 psi) in 100 kPa (15 psi) intervals.
11. As test is in progress, watch the gauge to assure the gauge readings follow the commanded pressures. Use a dry erase marker to mark the face of the gauge because it will be difficult to record the readings in time.
12. Oil pressure maximum and minimum values at idle should be checked using the following procedure:

IMPORTANT: For proper reverse operation, it is important to have at least 1206 kPa (175 psi) of system pressure in reverse at 70°C (158°F).

- With gauge connected and trans at operating temperature.
- With engine idling in Park (P), line pressure should be 400 - 600 kPa (58 - 72 psi).
- Remove line pressure fuse (10 amp TRS LP) UHJB.
- With engine idling in P, pressure should be 1206 - 1690 kPa (175 - 245 psi).

NOTE: High value may be slightly lower if transaxle temperature is greater than 110°C (230°F).

IMPORTANT: With engine in Park, and the 10 amp TRS LP line pressure fuse removed, minimum pressure should be 1206 kPa (175 psi).

13. Remove pressure gage, install temperature sensor, use Saturn P/N 21485278 sealant with Teflon on threads (or equivalent). After the sensor has been connected, clear Diagnostic Trouble Codes (DTCs) caused by having the sensor disconnected.

Torque: 8 Nm (71 inch lbs)
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Test line pressure when the problem would normally occur.

Let me know what you find.

Take care,
Joe

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