Test B2 - Act Sensor

Fig 1: Air Charge Temperature (ACT) Sensor Circuit

To prevent replacement of good components, be aware that the following non-EEC related areas may be at fault: cooling system, improper engine oil level, or air cleaner duct problems. Ambient air temperature must be at least 50°F (10°C) for test results to be valid. Avoid performing test in unusually hot or cold conditions.

1. Service Code 24: Checking ACT Sensor. Code 24 indicates that the ACT is out of the Self-Test limit range. Correct range for Self-Test measurement is 0.3-3.7 volts. Possible causes for this code are: ACT resistance out of limits or a faulty ECA. For vehicles with ACT sensor mounted in intake manifold, go to next step. If sensor is properly mounted in air cleaner on all other models, go to next step. If sensor is not properly mounted, install ACT sensor properly and repeat QUICK TEST.
2. Checking VREF at TPS. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale and disconnect TPS. With KOEO, measure voltage between VREF and SIG RTN at TPS harness connector. If reading is less than 4 volts or more than 6 volts, go to TEST A3 - REF  . VOLTAGE, step 1). If reading is between 4 and 6 volts, connect TPS and go to next step.
3. Checking ACT With Engine Off. Start engine and ensure engine reaches normal operating temperature. Turn key off and wait 10 seconds. Disconnect ACT sensor, set DVOM on 200K-ohm scale and measure ACT sensor resistance. If reading is less than 1100 ohms or more than 58K ohms, check function of heat stove duct valve. If valve is operating correctly, replace ACT sensor. Connect ACT sensor, and repeat QUICK TEST. If reading is between 1100 and 58K ohms, go to next step.
4. Checking ACT With Engine Running. Turn key off. Disconnect ACT sensor harness. Set DVOM on 200K-ohm scale and run engine for 2 minutes. While engine is running, measure ACT sensor resistance. If reading is between 2400 and 29K ohms, replace ECA. Connect ACT harness, and repeat QUICK TEST. If reading is less than 2400 ohms or more than 29,000 ohms, check function of heat stove duct valve. If valve works properly, replace ACT sensor. Repeat QUICK TEST.
5. Code 54: Generate Code 64. Code 54 indicates the ACT signal is greater than the Self-Test maximum value of 4.6 volts, which could also indicate an open circuit. Possible causes for this code are, open in harness wiring, faulty ACT sensor or faulty ECA. Turn key off and wait 10 seconds. Disconnect ACT sensor harness. Inspect for and repair any damaged wiring. Install a jumper wire between ACT SIGNAL and SIGNAL RETURN at connector. Perform KOEO SELF-TEST. If code 64 is displayed, replace ACT sensor. Remove jumper wire, connect ACT sensor, and repeat QUICK TEST. If code 64 is not displayed, remove jumper wire and go to next step.
6. Continuity Check of ACT Signal and Signal Return. Turn key off and wait 10 seconds. Leave ACT sensor harness disconnected. Disconnect ECA 60-pin connector. Inspect for and repair any damaged wiring. Install breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 25 and ACT SIGNAL at ACT connector, and between test pin No. 46 and SIGNAL RETURN at ACT connector. If both readings are less than 5 ohms, replace ECA and remove breakout box. Connect ECA and ACT sensor, and repeat QUICK TEST. If either reading is 5 ohms or more, repair opens in circuit. Remove breakout box, and connect ECA and ACT sensor. Repeat QUICK TEST.
7. Code 64: Generate Code 54. Code 64 indicates that the ACT signal is less than the Self-Test minimum value of 0.2 volt (grounded circuit). Possible cause for this fault are, faulty ACT sensor, short to ground in harness, faulty ECA. Turn key off and wait 10 seconds. Disconnect ACT sensor. Inspect for and repair any damaged wiring. Perform KOEO SELF-TEST. If code 54 is displayed, replace ACT sensor. Connect harness, and repeat QUICK TEST. If code 54 is not displayed, go to next step.
8. Checking VREF at TPS. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale and disconnect TPS. Turn key on, leaving engine off. Measure voltage at TPS harness connector between VREF and SIGNAL RETURN at TPS connector (refer to wiring diagram for TEST B8 - TPS  . If reading is less than 4 volts or more than 6 volts, go to TEST A3 - REF  . VOLTAGE, step 1). If reading is between 4 and 6 volts, connect TPS and go to next step.
9. Checking ACT Signal for Ground Short. Turn key off and wait 10 seconds. Disconnect harness at ACT sensor. Disconnect ECA 60 pin connector. Inspect for and repair any damaged wiring. Install breakout box and set DVOM on 200K-ohm scale. Measure resistance between test pin No. 25 and test pins No. 40, 46, and 60. If any reading is less than 10K ohms, repair shorts. Remove breakout box, and connect ECA and ACT sensor. Repeat QUICK TEST. If all readings are 10K ohms or more, replace ECA. Remove breakout box, and connect ECA and ACT sensor. Repeat QUICK TEST.
10. Continuous Memory Code 54: Check ACT Sensor. Code 54 indicates that the ACT signal was greater then the Self-Test maximum value sometime during vehicle operation. Possible causes for this fault are; faulty ACT sensor, open in harness or faulty ECA. Using KOEO CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for indication of fault while tapping ACT sensor lightly and wiggling connector. If fault is indicated, inspect connector and terminals. If connector and terminals are good, replace ACT sensor and repeat QUICK TEST. If no fault is indicated, go to next step.
11. Wiggle Testing ACT Harness. While in CONTINUOUS MONITOR (WIGGLE) TEST, wiggle and bend small sections of harness from ACT sensor to firewall. Repeat action from firewall to ECA. If fault is indicated, isolate fault and repair as necessary. Clear continuous memory codes and repeat QUICK TEST. If no fault is indicated, go to next step.
12. Inspecting Connectors and Terminals. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect both connector and connector terminals for obvious damage. If connectors and terminals are not okay, repair as necessary, clear continuous memory code and repeat QUICK TEST. If connectors and terminals are okay, and you are unable to duplicate fault at this time, clear continuous memory and repeat QUICK TEST.
13. Continuous Memory Code 64: Check ACT Sensor. Code 64 indicates that the ACT sensor signal was less than the Self-Test minimum value of 0.2 volt sometime during vehicle operation. Possible causes of this fault are; faulty ACT sensor, open in harness or faulty ECA. Using KOEO CONTINUOUS MONITOR (WIGGLE) TEST, observe VOM or diagnostic tester for indication of fault while tapping ACT sensor lightly and wiggling connector. If fault is indicated, inspect connector and terminals. If connector and terminals are good, replace ACT sensor and repeat QUICK TEST. If no fault is indicated, repeat step 11).