Test Pin Identification - Mustang

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: excessive blow-by, PCV malfunction, vacuum leak, fuel pressure or throttle linkage sticking or binding.

1) Throttle Position Sensor Integrity  Code 121 indicates TPS is inconsistent with MAF value. Code 124 indicates TPS value is higher than expected. Code 125 indicates TPS value is lower than expected.

Turn ignition off. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Install breakout box and connect ECA. Set DVOM on 20-volt scale. Connect DVOM to test pins No. 47 and 46. Operate throttle slowly to WOT, and slowly release to closed position. See TEST DH for schematics and specific engine values. If there are any sudden voltage variations, ensure TPS is properly installed on throttle body. If TPS is properly installed, replace TPS; remove breakout box, reconnect all components and rerun QUICK TEST. If there are no sudden voltage variations, go to step 6) (for Continuous Memory Code 121), or go to next step (for all other codes).

2) Check Throttle Body  Check throttle and/or speed control linkage for binding and smooth operation. Inspect throttle body for contamination. Check engine vacuum hoses. Refer to VECI decal for proper vacuum hose routing. Check for air leak between ISC solenoid and MAF sensor. If all checks reveal no problems, go to next step. If problems are found, repair as necessary; remove breakout box, reconnect all components and rerun QUICK TEST.

3) Check MAP/BP Sensor Output  Refer to TEST DF for schematic. With MAP/BP tester connected and ignition on, measure sensor output voltage. If voltage output is within range at specific altitude, remove MAP/BP tester and go to next step. See MAP SENSOR VOLTAGE OUTPUT  for specification. If output reading is outside range, replace MAP/BP sensor; remove tester, reconnect all components and rerun QUICK TEST.