DTC 41

Chart - Code 41 Cam Sensor Signal:

Wiring Diagram for Cam Sensor Signal:

CODE 41 - CAM SENSOR CIRCUIT



Circuit Description:
For timing spark plug firing, a cam sensor "hall effect" switch is used. The cam sensor sends a signal (Sync-Pulse) to the ignition module, when cylinder #1 is 25 degrees after top dead center on the compression stroke. This signal is used to start the correct coil firing sequence, and to enable sequential fuel injection. The engine will continue to run if the cam signal is lost while running, however, will not restart after shut down. If the failure is in the cam signal output portion of the C-3 I module (terminal "J") or the "SFI" cam signal CKT 630 to Electronic Control Module (ECM) terminal "All", the ECM will switch to the simultaneous fuel injection mode and continue to run. The engine can be re-started but will continue to run in the simultaneous mode as long as the fault is present. In either failure mode a Code 41 will be stored. Code 41 is set when the engine is running and a Cam sensor signal is not received by the ECM for 1 second.



Test Description: Numbers below refer to circled numbers on the diagnostic chart.
1. Checks to see if ECM recognizes a problem, and sets Code 41. If the engine cranks, but will not start and a Code 41 was displayed, the fault is in the ignition system portion of the Cam Sensor circuit and should be diagnosed using CHART A-3, "Cranks But Will Not Run". The voltage to ECM terminal "A 11" is supplied by the ignition module. If voltage reading is below 6 volts, the fault is in CKT 630, a poor connection at the C-3 I module, or a faulty C-3 I module.

Diagnostic Aids:
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation.


Check For:
Poor Connection or Damaged Harness Inspect, ECM harness connectors for backed out terminal "A 11", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

Intermittent Test If connections and harness check out OK, monitor A Digital Voltmeter connected from ECM terminal "A 11" to ground while moving related connectors and wiring harness. If the failure is induced, the voltage reading will change. This may help to isolate the location of the malfunction.