DTC 42

Diagnostic Chart:

Electrical Schematic:

CIRCUIT DESCRIPTION
When the distributor shaft rotates, a magnetic field is generated due to changes in the air gap between the Camshaft Position (CMP) sensor and the signal rotor. As a result, a reference voltage is induced in the CMP sensor. This reference voltage is monitored by the Engine Control Module (ECM) to determine the crank angle input. The ECM uses the crank angle input to determine when to ground the igniter, thus controlling the ignition coil and ignition timing.

Diagnostic Trouble Code (DTC) 42 will set if the following condition is met for 3 seconds:
- No CMP sensor signal at the ECM.

CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. The checks for an open, a short to ground or a short to voltage in WHT wire between ECM and distributor or for a faulty ECM.
2. This checks for an open in BLU/BLK wire between MAIN relay and distributor.
3. This checks for an open in BLK wire between distributor and ground G110.
4. This checks for a faulty CMP sensor.

DIAGNOSTIC AIDS
A loose or damaged CMP sensor could cause an intermittent DTC 42.

A misaligned CMP sensor or improper air gap could result in DTC 42 or intermittent "Engine Cranks But Will Not Run." Refer to Ignition System / Distributor / Testing and Inspection for diagnostic procedures. Testing and Inspection

INTERMITTENT MALFUNCTIONS
An intermittent malfunction may be caused by a poor connection, rubbed through wire insulation, or a wire broke inside the insulation. Inspect harness connectors for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals and poor terminal-to-wire connections before component replacement.