Diagnostic Aids

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When testing circuits to the SDGM access can be accomplished by removing the instrument panel center trim panel. Note that this procedure does not allow removal of the SDGM, only access to the connector. Refer to Instrument Panel Center Trim Panel Replacement (Cadillac) , Instrument Panel Center Trim Panel Replacement (Except Cadillac) .
DTC U1816 can set current in the HPCM, ECM, and the SDGM.
If DTC U1816 is only set in the HPCM, the PIM must be replaced due to all circuits between the HPCM and MCM being internal to the PIM.