DTC 56

DTC 56 Injection Pump Calibration Resistor Error:

Injection Pump Calibration Resistor Error:

CIRCUIT DESCRIPTION
The Powertrain Control Module (PCM) uses a calibrated resistor mounted internally in the injection pump to determine fuel rates. The resistor value is stored in the PCM memory. If the PCM memory has been disturbed or the PCM has been replaced, the PCM will relearn the resistor value on the next ignition cycle.

DIAGNOSTIC TROUBLE CODE (DTC) 56 WILL SET WHEN
PCM has lost its memory and is unable to read a resistor value on CKT 985 on the next ignition cycle. Possible poor performance problem.

ACTION TAKEN (PCM will default to)
A current and history DTC will store and turn "ON" the Malfunction Indicator Lamp (MIL). The PCM will default to the lowest fuel table.

DTC 56 WILL CLEAR WHEN
The fault condition(s) no longer exist, and the ignition switch is cycled "OFF" then "ON."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This step will determine if DTC 56 is a hard failure.

DIAGNOSTIC AIDS
Check connection at fuel injector driver. Clear DTC, and cycle ignition. If DTC clears. treat condition as an intermittent.