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Test B13 - NDS & A/C

NOTE: Perform this test when Service Code 67 or 79 is displayed during QUICK TESTS or when directed here by other test procedures. This test is designed to diagnose the following:

  1. 1)

    Code 67 System Identification. Code 67 indicates that during engine cranking or KOEO SELF-TEST, signal voltage was greater than specification at test pin No. 10 (A/C input) or test pin No. 30 (NDS). Possible causes for this fault are: A/C circuit shorted to power, Neutral clutch/drive circuits open, Neutral clutch/drive switch open, or a faulty ECA. Go to step 9).
    Fig 1: Neutral Gear/Clutch Circuit Diagram
    G120728
    NOTE: There is a break in the test step sequence. No steps have been omitted.

  2. 9)

    Checking A/C Input Voltage. Ensure A/C is switched "OFF". If A/C was on, rerun QUICK TEST. If Code 67 or 79 is displayed, continue with this test. Install breakout box and leave ECA disconnected. With KOEO, set DVOM on 20-volt scale. Measure voltage at test pin No. 10 at the breakout box and chassis ground. If reading is greater than one volt, remove breakout box and repair short in A/C clutch power circuit. If voltage is less than one volt replace ECA, except on vehicles equipped with E4OD transmissions. Vehicles equipped with E4OD transmissions, go to TEST D25 - E4OD TRANS  , step 1). Reconnect all components and rerun QUICK TEST.

  3. 10)

    Checking A/C Input Circuit. A low idle with A/C switched "ON" could result in the ECA not receiving or recognizing A/C input on pin No. 10. Turn key off and wait 10 seconds. Disconnect ECA, inspect pins, and install breakout box. Leave ECA disconnected. Set DVOM on 20-volt scale. With KOEO, and A/C on, measure voltage between test pins No. 10 and 40. If voltage is greater than 10.5 volts, replace ECA. Reconnect all components and rerun QUICK TEST. If voltage is less than 10.5 volts, service open in A/C circuit and rerun QUICK TEST.
    Fig 2: A/C Clutch Circuit Diagram
    G120733

  4. 11)

    Checking Inoperative A/C With High Idle. A high idle condition with the A/C dash switch in the "ON" position may be the result of a lack of signal reaching the A/C clutch. Turn key off and wait 10 seconds. Disconnect ECA, inspect pins, and install breakout box. Leave ECA disconnected. Disconnect A/C clutch connector. Set DVOM on 20-volt scale. With KOEO, turn on A/C. Measure voltage between input pin on fan connector and test pin No. 40 at the breakout box. If voltage is greater than 10.5 volts, go to next step. If voltage is less than 10.5 volts, repair open circuit and rerun QUICK TEST.

  5. 12)

    Check Continuity of A/C Clutch. With KOEO, disconnect A/C clutch harness connector. Measure resistance across both pins of A/C clutch. If resistance is within normal specification of 2.14-3.34 ohms, fault was probably due to faulty connection. If resistance was not within specification repair or replace A/C clutch as necessary.

  6. 13)

    Checking Continuity of A/C Cycle Pressure Switch Circuit. Turn key off and wait 10 seconds. Disconnect ECA, inspect pins, and install breakout box. Leave ECA disconnected. Disconnect A/C cycle pressure switch. Turn on A/C switch. Set DVOM on 200-ohm scale. Measure resistance between test pin No. 43 at the breakout box and battery positive side of the A/C cycle pressure switch. Measure resistance between test pin No. 10 at the breakout box and negative side of the A/C cycle pressure switch connector. If both resistances are less than 5 ohms, EEC-IV system is not at fault. Repair or replace cycle pressure switch. If resistances are greater than 5 ohms, repair open circuit and rerun QUICK TEST.

  7. 14)

    Check A/C Demand and A/C Cycle Pressure Switch For Short to Power. Turn key off. Disconnect ECA, inspect pins, and install breakout box. Leave ECA disconnected. Ensure A/C switch is off. Set DVOM on 20-volt scale. With KOEO, measure voltage between test pin No. 43 and chassis ground. If voltage is greater than 1.0 volt, EEC-IV is not at fault. Repair or replace A/C switches or electrical circuit. If voltage is less than 1.0 volt, reconnect components and check switch operation. If switches are okay, repair short in circuit wiring and rerun QUICK TEST.

  8. 15)

    Checking NDS Circuit For Short to Ground or Closed NDS. Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector, inspect pins, and install breakout box. Place transmission in Drive. Set DVOM on 200K-scale. Measure resistance between test pin No. 30 and test pin No. 40 or 60 at breakout box. If resistance is greater than 10K ohms service high idle condition. If resistance is less than 10K ohms, service circuit short or closed NDS and retest.
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