Test K - Idle Speed Control (ISC Dc Motor)
- Code 12. If code 58 is also present, go to TEST H . If code 58 is not present, go to next step.
- If code 31 present, go to TEST DD . If code 41 present, go to TEST J . If no code 31 and/or 41, go to step 3).
- Check throttle plates and linkage for binding. Check speed control (if equipped) for binding. If okay, go to step 4). If not okay, service as required and repeat QUICK TEST .
- Turn ignition off and wait 10 seconds. Disconnect 60-pin connector at ECA and inspect. Connect breakout box and leave ECA disconnected. Disconnect harness at ISC motor. With DVOM on 200 ohm scale, check continuity from box pin 41 to negative ISC circuit and from box pin 21 to positive ISC circuit at ISC harness connector. If both are less than 5 ohms, go to step 5). If either 5 ohms or more, repair faulty circuit and repeat QUICK TEST .
- Turn ignition on. Breakout box connected and ECA and ISC disconnected. With DVOM on 20 volt scale, measure voltage from box pin 41 to pins 40 and 60. Then measure from box pin 21 to pins 40 and 60. If all less than one volt, go to step 6). If one volt or more, repair short circuit and repeat QUICK TEST . If code 12 still present, replace ECA.
- Turn ignition off and wait 10 seconds. Breakout box connected and ECA and ISC disconnected. With DVOM on 200K ohm scale, measure resistance from box pin 41 to pins 40, 46 and 60 in turn. Then measure resistance from box pin 21 to pins 40, 46 and 60 in turn. If all read infinity, go to next step. If any 10K ohms or less, repair faulty circuit and repeat QUICK TEST . If code 12 still present, replace ECA.
- Turn ignition off and wait 10 seconds. Breakout box connected and ECA and ISC disconnected. With DVOM on 20 volt scale, connect positive lead to box pin 1 and negative lead to ground. If 10.5 volts or more, go to step 8). If less than 10.5 volts, repair open in circuit No. 37 and repeat QUICK TEST . If code 12 still present, go to step 8).
- Turn ignition off and wait 10 seconds. Breakout box connected and ECA disconnected. Connect harness at ISC DC motor. Insert jumper wires between box pins 21 and 1 and between box pin 41 and ground. If ISC motor shaft extends 2" (51 mm), go to step 9). If not, replace DC motor and repeat QUICK TEST .
- Turn ignition off and wait 10 seconds. Breakout box connected and ECA disconnected. Insert jumper wires between box pins 41 and 1 and between box pin 21 and ground. If ISC motor shaft retracts, go to step 10). If not, replace DC motor and repeat QUICK TEST .
- Turn ignition off and wait 10 seconds. Breakout box connected and ECA disconnected. Insert jumper wires as outlined in step 8). If motor shaft extends, replace ECA and repeat QUICK TEST . If not, replace DC motor and repeat QUICK TEST .
- Code 13. Deactivate Self-Test and prepare vehicle for normal engine operation. Turn A/C on, if equipped. Start engine. Run for 3 minutes while alternating between idle for 30 seconds and part throttle for 5 seconds. If idle speed is erratic, check and repair vacuum leaks and service codes 22, 31, 41 and 58 before continuing. If idle speed is not erratic, go to next step.
- Connect test equipment and perform KEY ON-ENGINE RUNNING (KOER) SELF-TEST . If code 13, go to step 13). If no code 13, repair other codes as required.
- Check choke and throttle linkage for sticking or binding. Check to ensure throttle is not stuck on high step of cam. Repair as required and repeat QUICK TEST . If no binding or sticking, go to step 14).
- Perform KEY ON-ENGINE OFF (KOEO) SELF-TEST . Record On Demand codes. If code 68, go to TEST H , step 5). If no code 68, check anti-diesel speed adjustment.