Sensor Checking
- Turn ignition switch "OFF". Disconnect coupler from ECM. Connect ohmmeter between terminal No. 4 (coolant thermal switch) of disconnected coupler and terminal No. 19 (ground). Measure resistance.
- Repeat resistance check with terminal Nos. 5 (idle micro switch), 6 (engine compartment thermal switch), 14 (high altitude compensator) and 15 (WOT micro switch). See Sensor Resistance Chart.
- If ohmmeter readings are not as specified, sensor or lead wire may be faulty. Reconnect coupler to ECM after sensor check is completed.
SENSOR RESISTANCE CHART
| Sensor | Pin | Ohms | Condition |
|---|---|---|---|
| Thermal Switch | 4 | 0 | Coolant Temperature low |
| " | " | Infinity | Coolant Temperature above 116°F (47°C) |
| Idle Micro Switch | 5 | 0 | With engine warm |
| " | " | Infinity | Accelerator slightly depressed |
| High Alt. Compensator | 6 | Infinity | Altitude below 4000 ft |
| " | " | 0 | Altitude above 4000 ft |
| Engine Compartment Thermal Switch | 14 | 0 | Engine compartment temperature low |
| " | " | Infinity | Engine compartment temp. above 68°F (20° C) |
| WOT Micro Switch | 15 | Infinity | Accelerator not depressed |
| " | " | 0 | Accelerator fully depressed |