XB135 - KOEO Code 524/543: Is Continuous Code 583 Present

Key On Engine Off Diagnostic Trouble Codes (DTC) 524/543 indicate that when the Powertrain Control Module (PCM) commanded the fuel pump on, voltage was not detected on Fuel Pump Monitor (FPM), (PCM Pin 8). Although DTC 524 refers to the low speed output (Variable Control Relay Module (VCRM) Pin 24) and DTC 543 refers to the high speed output, it is not possible to distinguish between circuits due to the vehicle wiring and fuel pump operating strategy.

Continuous Memory DTC 583 indicates that when the fuel pump was activated. the power-to-pump circuit exceeded the normal current draw. This could be due to a hard fault or an intermittent condition.

Possible causes are:

Without DTC 583:

- Open in power-to-pump circuit between VCRM and FPM splice.

- Open in B(+) supply to VCRM (Pins 4 and 5).

- Left Heated Oxygen Sensor (HO2S) short to power.

With DTC 583:

- Power-to-pump/FPM circuit short to ground.

- Is Continuous Memory DTC 583 present?

Yes -- Go to XB136. XB136 - Clear and Attempt to Regenerate Code 583

No -- Go to XB144. XB144 - Does Engine Start With HFP Relay Disconnected