DTC 41

Code 41 Chart:

Code 41 Wiring Diagram:

CIRCUIT DESCRIPTION:


The ignition module sends a reference signal to the ECM once per revolution to indicate crankshaft position so that the ECM can determine when to pulse the injectors for cylinders 2 and 3 in the ASDF fuel control mode. This signal may be described as a synchronization signal called the 1X reference because it occurs 1 time per revolution. The ignition module applies 5 volts from terminal "G" through circuit 969 to ECM terminal "BC5" and in effect, switches this circuit to ground for a very short period of time, 125 degrees before TDC of cylinders 2 and 3. Code 41 is set if the ECM receives (8) 2X reference pulses with no 1X reference pulses. When Code 41 is present, the ECM pulses the injectors in the SSDF (simultaneous) mode.

NOTE: Because of all the possible color code combinations used on electrical wiring diagrams, always refer to ECM CONNECTOR IDENTIFICATION under ELECTRICAL AND ELECTRONIC WIRING DIAGRAMS for correct color code identification of circuit.



TEST DESCRIPTION: Numbers below refer to circled numbers on the diagnostic chart.

1. This test determines if the ECM recognizes a problem. If it doesn't set a code 41 at this point the problem is intermittent and could be due to a loose connection


2. This step simulates the 1X signal. The ECM should recognize the drop in voltage as the test light is removed, if the circuit and the ECM are OK. This step will give accurate results only if the chart sequence is used - ignition "OFF", ignition "ON", "Scan" tool set to 1X reference and terminal "G" touched with the test light probe.


3. If the ECM did not recognize the simulation of the 1X signal, circuit 969 may be open or shorted to ground or voltage. If circuit 969 is OK, the ECM is faulty.

4. Step 2 indicated that circuit 969 is OK and the ECM is capable of recognizing the simulated 1X reference pulse. This indicates either a poor connection at ignition module terminal "G" or a faulty ignition module caused the Code 41.




DIAGNOSTIC AIDS:

An intermittent may be caused by a poor connection, rubbed through wire insulation, or a wire broken inside the insulation. Inspect ECM harness connectors terminals "BC5" and the ignition module terminal "G" for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.