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Circuit Test A - System Inoperative

  1. Verify condition. Check all electrical and vacuum connections. Service as necessary. If connections are okay, apply brakes and observe brakelights. If brakelights do not work, repair circuit. If brakelights are okay, go to next step.
  2. Check clutch switch for proper operation (manual transmission). Service as necessary. If clutch switch is okay, check throttle actuator cable. Adjust or service as necessary. If throttle actuator cable is okay, check throttle linkage for proper operation. Adjust or service as necessary. If throttle linkage is okay, go to next step. On all models except Continental, Cougar, Sable, Taurus and Thunderbird, go to step 5).
  3. On Continental, Cougar, Sable, Taurus, Tempo, Thunderbird and Topaz, check vacuum hoses and repair as necessary. On Continental, Cougar, Sable, Taurus and Thunderbird, test vacuum check valve by disconnecting hose between check valve and servo, at servo end. Apply 18 in. Hg vacuum to check valve. If vacuum does not hold, replace check valve. If check valve is okay, check vacuum dump valve. Adjust or replace vacuum dump valve as necessary. On all models except Cougar and Thunderbird 3.8L SC, if dump valve is okay, go to step 5).
  4. On Cougar and Thunderbird 3.8L SC, check aspirator check valve. Valve should hold 18 in. Hg vacuum. Replace aspirator check valve as necessary. If aspirator check valve is okay, check vacuum dump valve. Adjust or replace vacuum dump valve as necessary. If dump valve is okay, go to next step. On all models except Continental, Cougar and Thunderbird, check vacuum at servo. Normal servo operation requires a minimum of 2.5 in. Hg vacuum. If vacuum reading is correct, go to next step. If vacuum reading is not correct, check vacuum dump valve. Replace or adjust dump valve as necessary. If dump valve is okay, replace leaking vacuum hose.
  5. On all models, perform CONTROL SWITCHES  test under COMPONENT TESTS. Service or replace as required. If control switches are okay, perform appropriate SERVO ASSEMBLY  test under COMPONENT TESTS. Replace servo as necessary. If servo is okay, perform VEHICLE SPEED SENSOR (VSS) test under COMPONENT TESTS  . Replace VSS as necessary. If VSS is okay, go to next step.
  6. Perform AMPLIFIER TEST  under TESTING. If problem is corrected, replace amplifier. If problem is not corrected after AMPLIFIER TEST, inspect all connectors. Repair as necessary.
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