Engine Controls - Revised DTC 0090 Diagnostics
Bulletin No.: 05-06-04-039Date: June 07, 2005
SERVICE MANUAL UPDATE
Subject:
Revised DTC P0090
Models:
2004-2005 Chevrolet Kodiak, Silverado
2004-2005 GMC Sierra, TopKick
with 6.6L Diesel Engine (VIN 2 - RPO LLY)
This bulletin is being issued to revise DTC P0090 in the Engine Controls sub-section of the Service Manual. Please replace the current information in the Service Manual with the following information.
The following information has been updated within SI. If you are using a paper version of this Service Manual, please make a reference to this bulletin on the affected page.
DTC P0090
Circuit Description
The engine control module (ECM) supplies power and ground to the fuel rail pressure (FRP) regulator. The ECM monitors current on the circuits to detect a failure. If the current is outside of the expected range, DTC P0090 will set. DTC Descriptor
This diagnostic supports the following DTC:
DTC P0090 Fuel Pressure Regulator Control Circuit Conditions for Running the DTC
^ The ignition is ON.
^ The commanded FRP regulator current is between 400-1,500 mA. Conditions for Setting the DTC
The FRP regulator circuit current is not between 50-1,600 mA. Action Take When the DTC Sets
^ The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
^ The control module records the operating conditions at the time the diagnostic fails. The control module stores this information in the Freeze Frame/Failure Records.
Conditions for Clearing the MIL/DTC
^ The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
^ A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
^ A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
^ clear the MIL and the DTC with a scan tool.
Diagnostic Aids
There are no driveability concerns associated with the FRP regulator unless a DTC is present. The most likely cause of this DTC is a sticking FRP regulator.
If the fuel system pressure is actually too high, a fuel knock and smoke condition will exist.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
7. This step tests for battery voltage through the ECM to the FRP regulator.
8. This step tests for an open control circuit between the ECM and the FRP regulator.
9. This excessive current code can be set by voltage being applied between the ECM and the FRP regulator on the FRP control circuit.
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