Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
SYS.OK|MANUAL.DB● LIVE
HOMESERVICE MANUALSCHEVROLET1983STEP VAN P20, 5.7 M, AUTOMATIC, 400/M40REPAIR AND DIAGNOSISTRANSMISSIONAUTOMATIC TRANSOVERHAUL - THM 400TESTINGCONTROL PRESSURE RESULTSLINE PRESSURE TOO HIGH
1983 Chevrolet Step Van P20, 5.7 M, Automatic, 400/M40
Line Pressure Too High
1983 Chevrolet Step Van P20, 5.7 M, Automatic, 400/M40SECTION Line Pressure Too High
- Vacuum system leak or improper engine vacuum. Water in vacuum modulator. Modulator valve not operating properly or defective. Defective EGR valve.
- Detent switch actuated or shorted, detent solenoid stuck open. Detent feed orifice in spacer plate blocked, detent solenoid loose. Detent valve bore plug damaged. Detent regulator valve pin too short.
- Pump pressure regulator and/or boost valve stuck. Incorrect pump pressure regulator spring. Pressure boost valve installed backward. Too many pressure regulator valve spacers. Pump casting defective. Aluminum bore plug has hole or not working. Pressure boost bushing broken or not working.
- Control valve assembly-to-spacer gasket out of proportion, control valve assembly gaskets switched.
RENDER: 1.0x
NO RELATED
Recommended Tools & Savings
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
Affiliate disclosure: We may earn a commission at no extra cost to you.
When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.