Tools Required
DT 46450 (DW 240-010) Auto Transaxle Pressure Gage Set
The 4HP 16 A/T uses a trochoid type oil pump to produce hydraulic pressure, and pressure control solenoid 1 to control that pressure at the pressure regulator valve after the oil leaves the pump. Solenoid 1 is controlled by an electrical signal that ranges from 0-12 volts. A 12-volt reading corresponds to minimum line pressure of 89.9-124.7 psi (619-859 kPa) (6.2-8.6 bar). Zero volts corresponds to a maximum line pressure of 221.9-252.4 psi (1529-1740 kPa) (15.3-17.4 bar)
Line pressures are calculated for 2 sets of gear ranges, which 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 | 2500 | 221.9-252.4 psi (1529-1740 kPa) (1503-17.4 bar) |
ON | 2500 | 17.4-269.8 psi (119-1860 kPa) (1.2-18.6 bar) | |
Neutral, Park | OFF | 2500 | 221.9-252.4 psi (1529-1740 kPa) (1503-17.4 bar) |
ON | 2500 | 89.9-269.8 psi (619-1860 kPa) (6.2-18.6 bar) |
Before performing a line pressure check, verify that the pressure control solenoid is receiving the correct electrical signal from the transmission control module (TCM):
- Install a scan tool.
- Start the engine and set the park brake.
- Test for diagnostic trouble codes, including the code for a stored pressure control solenoid.
- Repair the vehicle if necessary.
- Inspect the fluid level and manual linkage.
- Install a scan tool and DT 46450 (1) a the line pressure port, clutch B (2) or E (3) ports on the transaxle case.
- Put the gear selector in Park and set the park brake.
- Start the engine and allow the engine to warm up in idle.
- Access "Solenoid 1 Control Mode" on the scan tool.
- Switch solenoid 1 ON/OFF and accelerate the engine to 2,500 RPM. Read the line pressure at each gear.
- Compare the data to the Line Pressure Chart. Refer to Line Pressure .
Notice: The total test running time should not be longer than 2 minutes. Running the test longer than 2 minutes may damage the transaxle.
Caution: Keep the brakes applied at all times in order to prevent unexpected vehicle motion. Personal injury may result if the vehicle moves unexpectedly.
If pressure readings differ greatly from the line pressure chart, refer to the appropriate diagnostic charts contained in this section.
Important: Clutch damage may occur. The scan tool 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.
