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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 78 (Engine Controls - Self-Diagnostics - 4.8L, 5.3L & 6.0L) >> Diagnostic Tests >> DTC P1635: 5-Volt Reference 1 Circuit >> Diagnostic Aids

Diagnostic Aids

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NOTE: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Verify that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

Using the Freeze Frame/Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and a fail. Operate the vehicle within the same Freeze Frame conditions such as RPM, load, vehicle speed, temperature etc. that you observed. This will isolate when the DTC failed.

For an Intermittent condition, see INTERMITTENT CONDITIONS  under SELF-DIAGNOSTIC SYSTEM.