Symptom Checks

Check the following items:

• On A/T models, Torque Converter Clutch (TCC), TCC solenoid or TCC circuit may not be functioning properly. See appropriate OVERHAUL or ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.
• For low idle with A/C on, (Econoline 4.6L, 5.4L and 6.8L), check ACCS PID value. See appropriate PIN VOLTAGE/PID VALUE CHARTS article. With A/C clutch engaged, ACCS PID value should indicate ON. If PID value indicates OFF, see TEST KM , step 10)  under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check fuel delivery fuel system. See TEST HB (natural gas vehicles) or TEST HC (except natural gas vehicles) under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check air intake system. See TEST HU under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article.
• Check engine mechanical condition. Check compression, camshaft, valve train components, etc. and repair as necessary. See appropriate article in ENGINES. If mechanical condition is okay, return to SYMPTOM DIAGNOSIS  to identify any additional symptoms or see TEST Z under SYSTEM TESTS in SELF-DIAGNOSTICS - EEC-V (GASOLINE) article and check for intermittent faults.