Line Pressure Check. Chevrolet Joy 2008

For 1990-2009 cars

Table 1: | Line Pressure Test Results
Table 2: | Line Pressure Test Diagnosis

### Time Lag Test

Important:

• | In this test, be sure to wait for at least one minute after moving the select lever back to "N" range before starting the next measurement.

• | Be sure to take the measurement when the engine is fully warmed up.

1. After checking the automatic transmission/transaxle (AT) level, block the front and rear wheels securely and depress the floor brake.
2. Start the engine and move the select lever from "N" to "D". Using a stop watch, measure the time it takes from this point until shift shock is felt.
3. Similarly, measure the time lag from "N" to "R" range.

Time Lag | Result | Probable Cause
--- | --- | ---

N - D Range = 0.8 Seconds

Time lag in shifting from "N" to "D" exceeds the specified level.

• | Low Clutch Slip

• | One-Way Clutch Slip

• | Damage of the Clutch Piston Oil Seal

• | Low Line Pressure

N - R Range = 0.8 Seconds

Time lag in shifting from "N" to "R" exceeds the specified level.

• | Low and Reverse Brake Slip

• | Reverse Clutch Slip

• | Damage of the Brake or Clutch Piston Oil Seal

• | Low Line Pressure

### Oil Pressure Test

1. Check the AT fluid level and condition. Refer to Transmission Fluid Check .
2. Attach the oil pressure gage to the oil pressure inspection hole in the transmission case.

Caution: Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly.

3. Block the front and rear wheels and apply the parking brake fully.

Important:

• | Ensure that the AT fluid does not leak after installing the oil pressure gage.

• | Do not hold the stall condition for longer than 5 seconds at a time. Be sure to cool the transmission, idling for at least 30 seconds before starting the next test.

4. Start the engine and depress the foot brake. Measure the oil pressure in "D" and "R" ranges when idling, and when the engine has stalled.
5. Compare the line pressure test results with the line pressure results in the following table. If the line pressure is not a specified, refer to the line pressure test diagnosis in this procedure for further evaluation.

#### Line Pressure Test Results

Engine Operation | "D" Range | "R" Range
--- | --- | ---
Idling | 470 kPa (68 psi) | 600 kPa (87 psi)
Stall | 1030 kPa (149 psi) | 1310 kPa (190 psi)

#### Line Pressure Test Diagnosis

Result | Probable Cause
--- | ---
"D" Range | "R" Range

• | Higher than the specified oil pressure when idling

• | Higher than the specified oil pressure when the engine has stalled

Faulty valve body

• | Lower than the specified oil pressure when idling

• | Lower than the specified oil pressure when the engine has stalled

• | Faulty oil pump

• | Damaged low clutch piston oil seal

• | Damaged reverse clutch piston oil seal

• | Damaged low and reverse brake piston oil seal