Diagnostic Aids
Perform this test only if Code 11/111 is present in during QUICK TEST or when directed here from another test. This test is intended to diagnose following components or systems.
- Idle Speed Control/By-Pass Air (ISC/BPA) System
- MAF System
To prevent replacing good components, be aware that following non-EEC-IV areas may be at fault.
- Faulty Power Or Ground Connections
- Ignition System (Distributor Cap, Rotor, Wires, Coil And Plugs)
- Basic Engine Mechanical Condition (Cam Timing, Compression, Etc.)
1) ISC/BPA Check - Try to start engine at part throttle. If engine starts and runs smoothly at part throttle, go to TEST KE, step 4). If engine does not function as described, go to step 3).
2) Check For RPM Drop - Turn ignition off. Connect a tachometer. Start engine. Disconnect ISC solenoid. If RPM drops or engine stalls, reconnect ISC solenoid and go to next step. If RPM does not drop, go to step 4).
3) Power To BP Sensor - Turn ignition off. Disconnect BP sensor connector. Connect BP tester between vehicle harness and BP sensor. See Fig 1 . Connect plugs of BP tester to DVOM. Set DVOM on 20-volt scale. Turn ignition on (engine off). If Green light is on, go to next step. If Green light is not on, repair open in VREF circuit. Disconnect BP tester. Reconnect components. Retest for symptom.
4) BP Tester Output Reading - Connect BP tester and DVOM. Set DVOM on 20-volt scale. Turn ignition on. Measure BP SIG voltage. Compare measured voltage with voltage specified in BP VOLTAGE OUTPUT table. If voltage is within specification for specified elevation, go to TEST H . If voltage is not within specification, replace BP sensor.
| Approximate Elevation (Feet) | Volts |
|---|---|
| 0 | 1.55-1.63 |
| 1000 | 1.52-1.60 |
| 2000 | 1.49-1.57 |
| 3000 | 1.46-1.54 |
| 4000 | 1.43-1.51 |
| 5000 | 1.40-1.48 |
| 6000 | 1.37-1.45 |
| 7000 | 1.35-1.43 |