408 7 ELECTRONIC CONTROL SYSTEMS DIAGNOSTICS
DTC 372
EFP is below normal operating range
• DTC 372 is set by ECM when measured fuel
pressure is less than expected pressure by 103
kPa (15 psi) for more than 30 seconds.
• DTC 372 can be set due to d irty fue l filter element,
fuel inlet restriction, debris in fuel tank, debris in
fuel regulator valve, failed fuel regulator valve,
failed fuel pump, bias low circuit, or failed EFP
sensor. See “Fuel Pressure and Aerated Fuel” –
Section 6.
• When DTC 372 is active the amber FUEL FILTER
lamp is illuminated.
Tools
• EST with MasterDiagnostics® software
• EZ-Tech® interface cable
• Digital Multimeter (DMM)
• 3-Banana Plug Harness
• 500 Ohm Resistor Harness
• Breakout Box
• Breakout Harness
• Terminal Te st Adapter Kit
EFP Operational Diagnostics
WARNING: To avoid serious personal injury,
possible death, or damage to the engine or veh
icle
– comply with the following:
Be careful to avo id rotating parts (belt
s and fan)
and hot engine surfaces.
1. Using EST, open the D_ContinuousMonito
r.ssn.
Figure 439 Continuous Monitor Test
2. To monitor signal voltage, run KOEO Continuous
Monitor Test. For help, see “Continuous Monitor
Test” in Section 3 (page 68).
3. Monitor EFP signal voltage. Verify an active DTC
for the EFP circuit.
4. If code is active, do step 6 and 7 to check circuit
for the EFP sensor using the following table.
• Circuit Checks for EFP Sensor
5. If code is inactive, wiggle connectors and wires
at all suspected problem loca tio ns. If circu it
continuity is interrupted, the EST display DTCs
related to the condition.
6. Disconnect engine harness from pressure sensor.
NOTE: Inspect connectors for damaged pins,
corrosion, or loose pins. Repair if necessary.
7. Connect Pressure Sens or Breakout Harness to
engine harness only.
EGES-270-1
Read all safety instructions in the "Safety Information" section of this manual before doing any procedures.
Follow all warnings, cautions, and notes.
© August 2008 Navistar, Inc.
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