Diagnostic Aids

WARNING: This page is about a different car, the 1995 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.

CID signal provides PCM information for fuel injector synchronization. The CID signal originates from Camshaft Position (CMP) sensor.

Enter this CIRCUIT TEST only when instructed during QUICK TEST. This test is only intended to diagnose the following:

* CID, PWR GND, SIG RTN and VPWR wiring harness circuits.

* Faulty Camshaft Position (CMP) sensor.

* Faulty Powertrain Control Module (PCM).

Fig 1: CID Wiring Harness Circuits

1) DTC P0340

This code indicates error has been detected in CMP sensor circuit. Possible causes for this fault are:

* CID circuit open or shorted wiring harness.

* PWR GND or VPWR circuit open.

* Faulty CMP sensor.

* Faulty ICM.

* Faulty PCM.

If engine starts, go to step 2). If engine does not start, go to PINPOINT TEST A: NO START in SYSTEM & COMPONENT TESTING - EEC-IV & EEC-V article.

2) Attempt To Generate DTC P0340

Clear PCM memory. Start engine. Raise engine speed to 1500 RPM for 10 seconds. Return to idle speed. Raise speed to 1500 RPM for 10 seconds again. Turn ignition off. Perform QUICK TEST. If DTC P0340 is not present, go to CIRCUIT TEST Z. If DTC P0340 is present, go to next step.

3) Check VPWR Circuit Voltage

Turn ignition off. Disconnect CMP wiring harness connector. Turn ignition on. Measure voltage between VPWR terminal at CMP sensor wiring harness connector and negative battery terminal. If voltage is 10.5 volts or more, go to next step. If voltage is less than 10.5 volts, repair open in VREF circuit. Clear PCM memory and repeat QUICK TEST.

4) Check PWR GND To CMP Sensor

Turn ignition off. Ensure CMP sensor is disconnected. Measure resistance between PWR GND circuit at CMP sensor wiring harness connector and negative battery terminal. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in PWR GND circuit. Clear PCM and repeat QUICK TEST.

5) Check Continuity Of CID Circuits

Leave ignition off. Disconnect PCM 104-pin connector. Inspect for damaged terminals and repair if necessary. Install EEC-V Breakout Box (014-000950), leaving PCM disconnected. Measure resistance between test pin No. 85 (CID) at breakout box and CID terminal at CMP sensor wiring harness connector. If each resistance is less than 5 ohms, go to next step. If either resistance is 5 ohms or more, repair open circuit. Clear PCM memory and repeat QUICK TEST.

6) Check CID Circuit For Short To Power

Leave CMP sensor disconnected. Turn ignition on. Measure voltage between test pin No. 85 and test pins No. 51 and 103 (PWR GND) at breakout box. If voltage is less than 1.0 volt, go to next step. If voltage is 1.0 volt or more, repair CID circuit short to power. Clear PCM memory and repeat QUICK TEST.

7) Check CID Circuit For Short To Ground

Turn ignition off. Leave CMP sensor disconnected. Measure resistance between test pin No. 85 and test pins No. 51, 91 and 103 at breakout box. If resistance is 10,000 ohms or more, go to next step. If any resistance measurement is less than 10,000 ohms, repair short to ground or SIG RTN in CID circuit. Clear PCM memory and repeat QUICK TEST.

8) Check For Short In PCM

Leave ignition off and CMP sensor disconnected. Connect PCM to breakout box. Measure resistance between test pin No. 85 and test pins No. 23, 51, 71, 91, 97 and 103 at breakout box. If each resistance measurement is 500 ohms or more, go to next step. If any resistance measurement is less than 500 ohms, replace PCM and repeat QUICK TEST.

9) Check CMP Sensor Output

Turn ignition off. Reconnect CMP sensor wiring harness connector. Set DVOM on AC scale to monitor less than 5 volts. Start engine. Measure voltage between test pins No. 85 and test pins No. 51 and 103 while varying engine speed. If voltage varies more than 0.1 volt, replace PCM and repeat QUICK TEST. If voltage does not vary more than 0.1 volt, replace CMP sensor and repeat QUICK TEST.