Quote:
Originally Posted by Blue Bowtie
JC - The '94 does use the auxiliary oil pressure switch as a redundant backup to the pump relay (orange to gray wires), or at least mine does (Impala).
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I found a diagram for the earlier 4.3L L99 caprice vin W. in that schematic the oil pressure switch is connected across the fuel relay power contacts that feed the fuel pump. the fuel relay drops out after the start , then the oil pressure switch takes over.
on the 1996 the oil pressure switch just controls the dash light. also the fuel relay is always energized with normal engine operation . the PCM controls the fuel pump relay with OPTI distributor signals.
why this was done at the end of production is weird.