Operation CHARM: Car repair manuals for everyone.
Hosted by mcallihan.com

Circuit Description and Diagnostic Chart



SYSTEM: Vacuum Switching Valve (VSV) For Fuel Pressure Control

WIRING DIAGRAM





CIRCUIT DESCRIPTION




The engine control module (ECM) turns on a vacuum switching valve (VSV) to draw the air into the diaphragm chamber of the pressure regulator if it detects that the temperature of the engine coolant is too high during engine starting. The air drawn into the chamber increases the fuel pressure to prevent fuel vapor lock at high engine temperature in order to help the engine start when it is warm.
Fuel pressure control ends approx. 90 seconds. after the engine is started.

DIAGNOSTIC CHART
1. Check VSV for fuel pressure control.
^ If OK proceed to step 2.
^ If not OK replace VSV.

2. Check voltage of VSV power source.
^ If OK Proceed to next circuit inspection shown in the matrix chart in Diagnosis by Symptom under "Powertrain Management Testing Procedures".
Testing and Inspection
^ If not OK proceed with step 3.

3. Check for open and short in harness and connector between EFI main relay and ECM.
^ If OK repair or replace harness or connector.
^ If not OK check and replace ECM.