6.5 electrical

[farmboy1989]

This is on my 94 electronic pump truck.Does the pcm run the lift pump until you get oil pressure and then the oil pressure switch runs it?......Also, where is the oil pressure switch located on this truck? We have a 97 gm electrical manual, is it relatively close to the 94? Also if you get a new ecm module do u get a new chip?

[farmboy1989]

Also if the ecm/computer is bad will it cause the timing to be off and put out tons of white smoke?

[tommac95]

White smoke generally either unburnt fuel [as if glowplugs NoGood] or a head/block/headgasket leak , allowing collant into combustion chamber. Can smell exhaust to distinguish.

Don't know '94 LP circuit. On '95 , When Cranking, the LP is ON via ignition switch/diode(and possibly FuelPump Relay). When Running the LP is ON , provided (1) harness good , (2) OPS good , (3) LP good , [OPS energizes LP from ignition switch]. ['96 & up PCM/ECM switches on LP after start , given input from OPS; LP ON when ignition on, and when cranking.]

[Robyn]

The oil pressure switch is (Looking from the front of the truck)
at the back of the engine, slightly to your right of the fuel filter and under all the wiring plugs. Its about 2-1/2" long and in a nasty place to get too.