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Line Pressure Test

CAUTION: DO NOT perform following pressure tests for longer than 2 minutes or transmission damage may occur.
  1. Ensure fluid level is correct and engine is in good operating condition before performing line pressure test. Ensure shift linkage is properly adjusted. See appropriate AUTOMATIC TRANSMISSION SERVICING article in TRANSMISSION SERVICING.
  2. Install a scan tester to diagnostic connector. See Figure. Install pressure gauge on transmission line pressure tap. See Fig 1. Apply parking brake. Ensure engine is at normal operating temperature.
  3. Access PCS CONTROL test in scan tool. Place gear selector in "P" position. Increase DESIRED PCS in .1 amp increments. Note line pressure reading. Line pressure reading should be the same with gear selector to "D" or "N" position.
  4. Check line pressure. See LINE PRESSURE SPECIFICATIONS table. Line pressure readings must be within specification. If line pressure reading is not within specification, see TROUBLE SHOOTING.
Fig 1: Installing Line Pressure Gauge
G92J12566Courtesy of GENERAL MOTORS CORP.
LINE PRESSURE SPECIFICATIONS

Current (Amps) Line Pressure
.02 170-190 psi (11.7-13.1 kg/cm2 )
.10 165-185 psi (11.3-12.7 kg/cm2 )
.20 160-180 psi (11.0-12.4 kg/cm2 )
.30 155-175 psi (10.7-12.1 kg/cm2 )
.40 148-168 psi (10.4-11.7 kg/cm2 )
.50 140-160 psi (9.6-11.0 kg/cm2 )
.60 130-145 psi (8.9-10.0 kg/cm2 )
.70 110-130 psi (7.5-8.9 kg/cm2 )
.80 90-115 psi (6.2-7.9 kg/cm2 )
.90 65-90 psi (4.5-6.2 kg/cm2 )
.98 55-65 psi (3.8-4.5 kg/cm2 )