Tools Required
DT 46450 (DW240-010) Auto Transaxle Pressure Gage Set
The 4HP 16 A/T uses a trochoid type oil pump to produce hydraulic pressure, and a pressure control solenoid, solenoid 1, to control that pressure at the pressure regulator valve, after it leaves the pump. The transaxle pressure control solenoid is controlled by an electrical signal that ranges from 0-12 volts, corresponds to minimum line pressure approximately 89.9-124.7 psi (619-859 kPa) and 0 volt corresponds to a maximum line pressure approximately 221.9-252.4 psi (1529-1740 kPa) in all ranges.
Line pressures are calculated for 2 sets of gear ranges, Drive-Park-Neutral and Reverse. This allows the transaxle line pressure to be appropriate for different pressure needs in different gear ranges.
Gear Range | Solenoid 1 | RPM | Pressure |
|---|---|---|---|
Drive, Reverse | OFF | 2.500 | 221.9-252.4 psi (1530-1740 kPa) |
ON | 2,500 | 17.4-269 psi (117-1860 kPa) | |
Neutral, Park | OFF | 2,500 | 221.9-252.4 psi (1529-1740 kPa) |
ON | 2,500 | 89.9-269.8 psi (619-1860 kPa) |
Before performing a line pressure check, verify that the pressure control solenoid is receiving the correct electrical signal from the TCM:
- Install a scan tool.
- Start the engine and set the parking brake.
- Check for a stored pressure control solenoid DTC, and other DTCs.
- Repair the vehicle, if necessary.
- Inspect the fluid level and manual linkage.
- Install a scan tool and DT 46450 (1) at the line pressure port, clutch B (2) or E (3) ports on the transaxle case.
- Put the gear selector in Park and set the parking brake.
- Start the engine and allow it to warm up at idle.
- Access the solenoid 1 control mode on the scanner.
- Switching solenoid 1 ON/OFF, accelerating the engine to 2,500 RPM, and then read the line pressure at each gear.
- Compare data to the Drive-Park-Neutral line pressure chart.
Notice: The total test running time should not be longer than 2 minutes. Running the test longer than 2 minutes may damage the transaxle.
Important: Brake must be applied at all times to prevent unexpected vehicle motion.
If pressure readings differ greatly from the line pressure chart, refer to Symptoms - Automatic Transmission .
Important: Clutch damage may occur.
The scanner is only able to control the pressure control solenoid in Park and Neutral with the vehicle stopped. This protects the clutches from extremely high or low pressures in Drive or Reverse range.
Refer to Line Pressure .
