FixVault
Home › Ford › 1987 › Thunderbird Base, 2.3 W, Automatic › Repair and Diagnosis › Engine Performance › System › 2.3L EFI/EFI Turbo Tests › Circuit Tests › VAF Sensor Check

VAF Sensor Check

Fig 1: VAF Sensor Check (Turbo Models Only)
G4263
  1. Code 56 Displayed. Turn key off and wait 10 seconds. Disconnect harness from airflow meter. Inspect for and repair any damaged wiring. Perform KOEO SELF-TEST. If code 66 is not displayed, go to step 5). If code 66 is displayed, go to next step. Disconnecting airflow meter also disconnects VAT sensor. Code 54 should be displayed. Ignore all codes except VAF codes at this time.
  2. Turn key off and wait 10 seconds. Leave harness disconnected from airflow meter. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage at harness connector between VREF and signal return. If reading is between 4.0 and 6.0 volts, replace airflow meter. Connect harness and repeat QUICK TEST  . If reading is less than 4.0 or more than 6.0 volts, go to TEST C - REFERENCE VOLTAGE  , step 1).
  3. Turn key off and wait 10 seconds. Leave airflow meter disconnected. Disconnect 60-pin connector from ECA. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200,000-ohm scale. Measure resistance between test pin No. 43 (27 on 2.3L EFI/Turbo engine) and test pins No. 26 and 57. If either reading is less than 10,000 ohms, repair short in wiring. Remove breakout box. Connect ECA and airflow meter and then repeat QUICK TEST  . If both readings are 10,000 ohms or more, replace ECA. Remove breakout box. Connect ECA and airflow meter. Repeat QUICK TEST  .
  4. Code 66 Displayed. Turn key off and wait 10 seconds. Disconnect harness from airflow meter. Install jumper wire between VREF and VAF signal at connector. Perform KOEO SELF-TEST. Ignore all codes except VAF codes at this time. If no codes are displayed, immediately remove jumper wire and go directly to step 9). If code 56 is displayed, replace airflow meter. Remove jumper wire, connect airflow meter, and then repeat QUICK TEST  . If code 56 is not displayed, remove jumper wire and go to next step.
  5. Turn key off and wait 10 seconds. Leave airflow meter disconnected. Turn key on, leaving engine off. Set DVOM on 20-volt scale. Measure voltage between VREF and signal return at airflow meter harness connector. If reading is less than 4.0 volts or more than 6.0 volts, go to TEST C - REFERENCE VOLTAGE  , step 1). If reading is between 4.0 and 6.0 volts, go to next step.
  6. With key off and airflow meter disconnected, disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between VAF signal at airflow connector and test pin No. 43 (27 on 2.3L EFI/Turbo engine). If reading is 5 ohms or more, repair open circuit. Remove breakout box, connect ECA and airflow meter. Repeat QUICK TEST  . If reading is less than 5 ohms, go to next step.
  7. Turn key off and wait 10 seconds. Leave ECA and airflow meter disconnected. Set DVOM on 200,000-ohm scale. Measure resistance between VAF signal and signal return at harness connector. Also measure resistance between VAF signal and negative battery terminal. If either reading is less than 10,000 ohms, repair shorts. Connect airflow meter and repeat QUICK TEST  . If both readings are 10,000 ohms or more, replace ECA. Remove breakout box, and connect ECA and airflow meter. Repeat QUICK TEST  .
    NOTE: A sharp snap of the throttle may not be sufficient to pass step 10). Be sure to move throttle to WOT. Use DYNAMIC RESPONSE CHECK as specified. For additional information see QUICK TEST DIAGNOSTIC AIDS  , DYNAMIC RESPONSE CHECK in front of this article.
  8. Code 76 Displayed. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Install breakout box and connect ECA to box. Set DVOM on 20-volt scale. Connect DVOM to test pin No. 43 (27 on 2.3L EFI/Turbo engine) and 46. Perform KOER SELF-TEST while observing DVOM. As soon as DYNAMIC RESPONSE CHECK signal is displayed, perform WOT. Reading on DVOM should increase by more than 2.0 volts from reading before WOT. Observe service codes at end of test. If reading increased by more than 2.0 volts, go to next step. If not, check air cleaner duct for obstructions. If okay, replace vane airflow meter.
  9. Observe KOEO SELF-TEST service codes at end of step 10). If code 76 is still displayed, replace ECA. Remove breakout box and repeat QUICK TEST  . If code 76 is not displayed, vane airflow meter is okay. Service other codes as necessary.
  10. Continuous Code 56 or 66 Displayed. Using CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for indication of fault while lightly tapping VAF sensor and wiggling connector. If a fault is indicated, disconnect connector. Inspect connector and terminals for damage. If connector and terminals are okay, replace VAF sensor and repeat QUICK TEST  . If no fault is indicated, go to next step.
  11. While in CONTINUOUS MONITOR (WIGGLE) TEST, shake, bend and wiggle small sections of EEC-IV harness from VAF sensor connector to firewall and from firewall to ECA. If fault is indicated, isolate and repair damaged wiring. Repeat QUICK TEST  . If no fault is indicated, go to next step.
  12. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connectors and terminals for obvious damage. If connectors and terminals are damaged, repair as necessary and repeat QUICK TEST  . If connectors and terminals are okay, fault cannot be duplicated at this time. Continuous code 56 or 66 testing is complete.
Fig 2: VAF Sensor Circuits (Turbo Models Only)
G6028
About FixVault