E043

Code E043 - Electronic Spark Control System Failure:

Wiring Diagram for Code E043 - Electronic Spark Control System Failure:

CODE E043 - ELECTRONIC SPARK CONTROL SYSTEM FAILURE

Circuit Description:

The ESC system is comprised of a detonation sensor and an ESC module.

As long as the ESC module is sending a voltage signal (8 to 10 volts) to the ECM (no detonation detected by the ESC sensor) the calculated spark advance (EST) remains unaffected by the ESC input.

When the sensor detects detonation, the module turns "OFF" the circuit to the ECM and the voltage at ECM terminal "B7" drops to 0 volts. The ECM then retards EST as much as 20° in one (1) degree increments, to reduce detonation. This happens fast and frequently enough that if looking at this signal with a DVM, you won't see 0 volts, but an average voltage somewhat less than what is normal with no detonation.

A loss of the Detonation sensor signal or a loss of ground at ESC module would cause the signal at the ECM to remain high. This condition would result in the ECM controlling EST as if no detonation were occuring. The EST would not be retarded, and detonation could become severe enough under heavy engine load conditions to result in pre-ignition and potential engine damage.

Loss of the ESC signal to the ECM would cause the ECM to constantly retard the EST to its max retard of 20° from the spark table. This could result in sluggish performance and cause a Code E043 to set.

Code E043 will set when:

a. Engine Running.
b. ESC input signal has been low more than 2.2 seconds.




Test Description: The following numbered steps correspond with the step numbers on the diagnostic chart.

1. If the ECM Data ED17 (Knock Signal) display is fluctuating widely, the ECM is monitoring a low voltage signal on circuit (457) at ECM terminal "B7".

2. Probing ESC harness terminal "C" with a test light connected to 12 volts should result in the "OLD PA3" (knock signal) display holding a steady reading due to over 8 volts having been applied to ECM terminal "B7" through CKT 457.

3. If over 6 volts is measured at ECM terminal "B7", CKT 457 is OK and the fault is due to a poor connection at the ECM or the ECM is faulty.




Diagnostic Aids:

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

Check For:

a. Poor Connection or Damaged Harness - Inspect ECM harness connectors for backed out terminal "B7", improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection and damaged harness.

b. Intermittent Test - If connections and harness checks out ok, monitor ED17 (OLD PA3/Knock Signal) display while moving related connectors and wiring harness. If the failure is induced, the "OLD PA3" display will abruptly change. This will help to isolate the location of the malfunction.