Diagnostic Aids
Perform this test only when directed by QUICK TEST. Ambient air temperature must be at least 50°F (10°C) to receive valid input from IAT sensor. Engine coolant temperature must be more than 50°F (10°C) to pass KOEO SELF-TEST and more than 180°F (82°C) to pass KOER SELF-TEST. Voltage values in this test are based on a 5-volt VREF signal. Values may vary up to 15 percent due to sensor and VREF variations.
This test is intended to diagnose:
* Intake Air Temperature (IAT) sensor.
* Engine Coolant Temperature (ECT) sensor.
* Wiring harness circuits (IAT, ECT and SIG RTN).
* Powertrain Control Module (PCM).
To prevent replacing good components, ensure the following non-EEC areas or components are not cause of problem:
- Coolant level low.
- Cooling system, water pump or fan.
- Engine operating temperature.
- Engine oil level low.
- Thermostat.
- Air cleaner duct.
- Ambient temperature.
1) Code 116: Check Operation & Installation Code 116 (ECT) indicates corresponding sensor is out of self-test range. Correct range for measurement is .3-3.7 volts. Check for following possible causes:
- Ambient temperature less than 50°F (10°C).
- Low coolant level.
- Faulty harness connector.
- Faulty sensor.
Start engine and run until engine is at normal operating temperature. If vehicle cannot be started, go to step 3). If vehicle stalls, go to TEST S. Ensure upper radiator hose is hot and pressurized. Repeat QUICK TEST. If Code 116 is present, go to next step. If Code 116 is not present but other codes are, service other codes as necessary.
2) Check VREF Circuit Voltage At TP Sensor Turn ignition off. Disconnect Throttle Position (TP) sensor. Turn ignition on. Measure voltage at TP sensor wiring harness connector between VREF and SIG RTN. If voltage is 4-6 volts, reconnect TP sensor and go to next step. If voltage is not 4-6 volts, go to TEST C.
3) Check Temperature Sensor Resistance Turn ignition off. Disconnect ECT sensor. Measure resistance between sensor terminals. See ECT SENSOR SPECIFICATIONS table. If resistance is not within specification, replace ECT sensor and repeat QUICK TEST. If resistance is within specification, perform following step as applicable.
- For diagnosing vehicles with ECT sensor and a no-start condition, DO NOT service Code 116 at this time. Go to TEST AA.
- For diagnosing vehicles with ECT sensor without a no-start condition, go to next step.
4) Check Temperature Sensor Resistance Warm engine to normal operating temperature. Turn ignition off. Disconnect ECT sensor. Run engine at 2000 RPM for 2 minutes. Measure resistance between sensor terminals. See ECT SENSOR SPECIFICATIONS table. If resistance is within specification, replace PCM and repeat QUICK TEST. If resistance is not within specification, replace ECT sensor and repeat QUICK TEST.
| Temperature °F (°C) | (1) Volts | (1) Ohms | ||
|---|---|---|---|---|
| 50 (10) | 3.51 | 58,750 | ||
| 68 (20) | 3.07 | 27,300 | ||
| 86 (30) | 2.60 | 24,270 | ||
| 104 (40) | 2.13 | 16,150 | ||
| 122 (50) | 1.70 | 10,970 | ||
| 140 (60) | 1.33 | 7700 | ||
| 158 (70) | 1.02 | 5370 | ||
| 176 (80) | 0.78 | 3840 | ||
| 194 (90) | 0.60 | 2800 | ||
| 212 (100) | 0.46 | 2070 | ||
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10) KOEO Code 113 Or 118: Induce Opposite Code (Code 112 Or 117) Code 113 (IAT) or 118 (ECT) indicate corresponding sensor signal is more than self-test maximum. Maximum signal voltage for IAT and ECT sensors is 4.6 volts. Possible causes for excess voltage signals are:
- Open circuit in wiring harness (IAT or ECT).
- Faulty connection.
- Faulty sensor.
- Faulty PCM.
Turn ignition off. Disconnect suspect temperature sensor. Connect a jumper wire between SIG RTN terminal at sensor and SIG RTN terminal at sensor wiring harness connector. Repeat KOEO SELF-TEST. If Code 112 or 117 is displayed, replace suspect sensor, remove jumper wire and repeat QUICK TEST. If Code 112 or 117 is not displayed, remove jumper wire and go to next step.
11) Check Sensor Signal & SIG RTN Circuits Continuity Turn ignition off. Disconnect suspect temperature sensor. Disconnect PCM 60-pin connector and inspect for damaged wiring. Repair as necessary. Install Breakout Box (49-UN01-058), leaving PCM disconnected. Measure resistance between test pin No. 7 (ECT sensor), or test pin No. 25 (IAT sensor) at breakout box and SIG RTN terminal at sensor wiring harness connector. Also, measure resistance between test pin No. 46 at breakout box and SIG RTN circuit at sensor wiring harness connector. If both readings are less than 5 ohms, replace PCM. Remove breakout box, reconnect all components and repeat QUICK TEST. If either reading is 5 ohms or more, repair open circuit. Remove breakout box, reconnect all components and repeat QUICK TEST.
20) KOEO Code 112 or 117: Induce Opposite Code (113 or 118) Code 112 (IAT) or 117 (ECT) indicates sensor signal is less than self-test minimum. Minimum signal for IAT and ECT sensor is 0.2 volt. Possible causes for this fault are:
- Circuit grounded in wiring harness.
- Faulty sensor.
- Faulty PCM.
- Faulty connection.
Turn ignition off. Disconnect suspect temperature sensor. Inspect connector for damaged pins, corrosion and loose wires. Repair as necessary. Repeat KOEO SELF-TEST. If Code 113 or 118 is displayed, replace suspect sensor and reconnect harness. Repeat QUICK TEST. If Codes 113 or 118 is not displayed, go to next step.
21) Check VREF Circuit Voltage At TP Sensor Turn ignition off. Disconnect suspect temperature sensor. Disconnect TP sensor. Turn ignition on. Measure voltage between VREF and SIG RTN at TP sensor wiring harness connector. If voltage is not 4-6 volts, go to TEST C. If voltage is 4-6 volts, reconnect TP sensor and go to next step.
22) Check Temperature Sensor Signal For Shorts To Ground Turn ignition off. Disconnect suspect temperature sensor. Disconnect PCM 60-pin connector and inspect for damaged pins, corrosion and loose wires. Repair as necessary. Install Breakout Box (49-UN01-058), leaving PCM disconnected. Measure resistance between test pin No. 7 (ECT), or 25 (IAT) and test pins No. 40, 46 and 60 at breakout box. If any reading is less than 10,000 ohms, repair short circuit. Remove breakout box, reconnect all components and repeat QUICK TEST. If all readings are 10,000 ohms or more, replace PCM. Remove breakout box, reconnect all components and repeat QUICK TEST.
90) Continuous Memory Code 112, 113, 117 Or 118: Check Sensor A Continuous Memory Code 113 or 118 indicates sensor signal is more than self-test maximum of 4.6 volts. Code is set during normal driving conditions. Continuous Memory Code 112 or 117 indicates sensor signal is less than self-test minimum of 0.2 volt. Code is set during normal driving conditions. Possible causes for these faults are:
- Faulty sensor.
- Open or grounded circuit in harness.
- Faulty PCM.
| Sensor | Continuous Memory Code |
|---|---|
| IAT | 112 Or 113 |
| ECT | 117 Or 118 |
Enter KOEO wiggle test mode. See CONTINUOUS MONITOR MODE (WIGGLE TEST) under QUICK TEST. Observe analog voltmeter or scan tester for indication of fault while tapping sensor lightly and wiggling sensor connector. If fault is indicated, disconnect and inspect connector and terminals. If connector and terminals are okay, replace sensor, clear continuous memory and repeat QUICK TEST. If fault is not indicated, go to next step.
91) Check EEC-IV Wiring Harness While in CONTINUOUS MONITOR MODE (WIGGLE TEST), observe analog voltmeter or scan tester while wiggling and bending wiring harness, a small section at a time, from sensor to cowl. Also, check harness from cowl to PCM. If fault is indicated, isolate fault and repair as necessary. Clear continuous memory and repeat QUICK TEST. If no fault is found, go to next step.
92) Inspect PCM & Wiring Harness Connectors Turn ignition off. Disconnect PCM 60-pin connector and inspect for damaged pins, corrosion and loose wires. If connectors and terminals are damaged, repair as necessary and repeat QUICK TEST. If connectors and terminals are okay and fault cannot be duplicated at this time, see INTERMITTENTS in TESTS W/O CODES article.