Diagnostic Aids
The CMP is located inside distributor housing. CMP sensor has a rotor plate with 360 slots at 1 degree intervals to signal engine speed to PCM. CMP sensor rotor plate has 6 slots at 60 degree intervals to signal crankshaft position to PCM.
Perform this test when directed by QUICK TEST or another test procedure. This CIRCUIT TEST is intended to diagnose:
- CMP sensor.
- Wiring harness circuits (CMP, CMPREF, VPWR and GND).
| Circuit | PCM Pin No. | (1) BOB Pin No. | Wire Color | ||||
|---|---|---|---|---|---|---|---|
| CMP | 31 & 40 | 56 | Red/Blue | ||||
| CMPREF | 22 & 30 | 43 | Red/White | ||||
| VPWR | 38, 47 & 109 | 6, 37 & 57 | Red/Black | ||||
| GND | ***** | ***** | (2) Black/Red | ||||
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1) Check Power To CMP Turn ignition off. Disconnect CMP sensor wiring harness connector. Turn ignition on. Measure voltage between CMP sensor wiring harness connector VPWR terminal and ground. If voltage is less than 10 volts, go to step 4). If voltage is 10 volts or more, go to next step.
2) Check Ground At CMP Turn ignition off. Leave CMP sensor disconnected. Measure resistance between CMP sensor wiring harness connector GND terminal and ground. If resistance is 5 ohms or more, repair GND circuit. If resistance is less than 5 ohms, go to next step.
3) Check CMP Sensor Turn ignition off. Remove distributor from engine, leaving CMP sensor connected. Turn ignition on. While slowly rotating distributor, measure voltage between CMPREF terminal at sensor connector and ground. Also measure voltage between CMP terminal at sensor connector and ground. If voltage does not fluctuate 0.0-5.0 volts, replace distributor and CMP sensor. If voltage fluctuates 0.0-5.0 volts, check CMP signal plate for damage and dust. If plate is okay, go to step 5).
4) Check Continuity Between CMP & Engine Cont Relay Turn ignition off. Disconnect CMP sensor. Disconnect engine cont relay wiring harness connector, located in left engine compartment fuse panel. Check for continuity between VPWR terminal of relay connector and VPWR terminal of CMP sensor connector. See Fig 2 . If continuity is not present, repair VPWR circuit. If continuity is present, go to CIRCUIT TEST VPWR.
5) Check Continuity Between CMP & PCM Turn ignition off. Leave CMP disconnected. Install Breakout Box (007-00033), leaving PCM disconnected. Check for continuity between breakout box test pin No. 56 and CMP terminal of CMP wiring harness connector. Also check for continuity between breakout box test pin No. 43 and CMPREF terminal of CMP harness connector. If continuity is not present, repair circuit as necessary. If continuity is present, replace PCM.