Diagnostic Aids
Perform this test when directed by QUICK TEST procedure. This CIRCUIT TEST is intended to diagnose:
- Wiring harness circuit (IGNS, IGNC, GND and PWR).
| Circuit | PCM Pin No. | (1) BOB Pin No. | Wire Color | ||
|---|---|---|---|---|---|
| IGNS | 1 | 36 | Blue | ||
| IGNC | 3 | 4 | Red | ||
|
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1) Check Power To Resistor/Condenser Turn ignition off. Disconnect resistor/condenser harness connector. Turn ignition on. Measure voltage between PWR (White/Red wire) terminal of resistor/condenser wiring harness connector and ground. If voltage is less than 10 volts, repair PWR circuit. If voltage is 10 volts or more, go to next step.
2) Check Power To Ignition Coil Turn ignition off. Disconnect ignition coil wiring harness connector. Turn ignition on. Measure voltage between PWR terminal of ignition coil harness connector and ground. If voltage is less than 10 volts, repair PWR circuit. If voltage is 10 volts or more, go to next step.
3) Check PCM Input Signal Turn ignition off. Install Breakout Box (007-00033). Connect PCM to breakout box. Try to start engine and run at idle. Measure voltage between breakout box test pin No. 4 and ground. If vehicle starts and voltage is less than 10 volts, go to step 7). If vehicle does not start and voltage is less than 10 volts, go to step 5). If voltage is 10 volts or more, go to next step.
4) Check PCM Output Signal Turn ignition off. Leave PCM connected to breakout box. Measure voltage between test pin No. 36 and ground. With engine idling, voltage should be 0.4-0.6 volt. With engine speed at 2000 RPM, voltage should be 1.1-1.3 volts. If voltage is not as specified, replace PCM. If voltage is as specified, ignition signal is okay. Repeat QUICK TEST. If Code 21 is still present, replace PCM.
5) Check Power Transistor Turn ignition off. Disconnect power transistor wiring harness connector. Measure resistance between terminals "A" and "B". See Fig 2 . Reverse ohmmeter test leads and measure resistance again. Both measurements should be more than 1,000,000 ohms. Measure resistance between terminals "A" and "C". Reverse ohmmeter test leads and measure resistance again. Both measurements should be more than 1,000,000 ohms. If resistance is not as specified, replace power transistor. If resistance is as specified, go to next step.
6) Check IGNS Circuit Turn ignition off. Leave power transistor wiring harness connector disconnected. Install Breakout Box(007-00033), leaving PCM disconnected. Measure resistance between breakout box test pin No. 36 and IGNS terminal of power transistor harness connector. Resistance should be 5 ohms or less. Measure resistance between breakout box test pin No. 36 and ground. Resistance should be 10,000 ohms or more. If resistance is as specified, test ignition coil and service as necessary. If resistance is not as specified, repair IGNS circuit.
7) Check Resistor Turn ignition off. Disconnect resistor/condenser wiring harness connector. Measure resistance between terminals "R" and "GN" of wiring harness connector. See Fig 3 . Resistance should be about 2200 ohms. If resistance is not as specified, replace resistor/condenser. If resistance is as specified, go to next step.
8) Check IGNC Circuit Turn ignition off. Leave resistor/condenser harness connector disconnected. Install Breakout Box (007-00033), leaving PCM disconnected. Measure resistance between breakout box test pin No. 4 and IGNC (Red wire) terminal of resistor/condenser harness connector. Resistance should be 5 ohms or less. Measure resistance between breakout box test pin No. 4 and ground. Resistance should be 10,000 ohms or more. If resistance is not as specified, repair IGNC circuit. If resistance is as specified, go to next step.
9) Check Ground Circuit Turn ignition off. Leave resistor/condenser harness connector disconnected. Disconnect power transistor and ignition coil wiring harness connector. Measure resistance between following connector terminals:
- Green wire terminal of ignition coil and power transistor.
- Green wire terminal of ignition coil and resistor/condenser.
- Black wire terminal of power transistor and ground.
If resistance is 5 ohms or more, repair IGNC circuit. If resistance is 5 ohms or less, replace PCM.