Powertrain Controls - ECM/PCM

Diagnostic Trouble Code 41:

Ignition Circuit:

CIRCUIT DESCRIPTION
When the system is running on the distributor ignition control module, that is, no voltage on the bypass line, the Distributor Ignition (DI) control module grounds the Ignition Control (IC) signal. The Engine Control Module (ECM) expects to sense no voltage on the IC line during this condition.

When the RPM for IC is reached (about 400 RPM), and bypass voltage applied, the IC should no longer be grounded in the ignition module so the IC voltage should be varying.

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

1. Diagnostic Trouble Code (DTC) 41 means the ECM has sensed an open IC circuit. This test confirms DTC 41 and that the fault causing the DTC is present.

2. Checks for a normal IC path through the ignition control module.

DIAGNOSTIC AIDS
If a DTC 41 was stored and the customer complaints of a "Hard Start," the problem is most likely an open IC line (CKT 423).

If the distributor wiring harness is routed too close to secondary ignition wires, a DTC 41 can result.

Refer to Intermittents in Diagnosis By Symptom. Testing and Inspection