oil preasure sending unit pinouts 99 pcm
11-29-2008, 02:47 PM
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oil preasure sending unit pinouts 99 pcm Did a search and can not find where the 3 wires from the oil pressure sending unit goes to the PCM (pinouts) Anyone know on a 99 PCM
11-29-2008, 02:52 PM
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11-29-2008, 05:17 PM
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Going from memory, I don't believe the ECM cares about oil pressure.. It's most likely just a gauge thing. I'd have to double check my manual to be sure though.
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11-29-2008, 07:41 PM
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about 2003 on the truck harnesses, I think the oil pressure started going to the PCM: Ground, 5 volt Ref, and Signal pack to PCM. PCM sent oil pressure info to cluster via serial data.
C2 Blue - Pin 58 - Tan/White - Oil pressure sensor signal
Not sure which pins are ground/reference. Anyways, its not needed for the PCM to operate. Programming can remove any circuit codes related to it.
Only other times i've seen 3 wires on oil pressure sensor, is if the oil pressure sender acted as a Fuel Pump Switch also. Typically the wires for this are Orange, Gray, Tan or Tan/White
C2 Blue - Pin 58 - Tan/White - Oil pressure sensor signal
Not sure which pins are ground/reference. Anyways, its not needed for the PCM to operate. Programming can remove any circuit codes related to it.
Only other times i've seen 3 wires on oil pressure sensor, is if the oil pressure sender acted as a Fuel Pump Switch also. Typically the wires for this are Orange, Gray, Tan or Tan/White
03-30-2019, 01:10 PM
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The orange and gray, if I'm not mistaken, are part of the fuel pump circuit. If oil pressure drops out, power is interrupted to fuel pump to protect the engine. The ECM could care less if it has oil pressure, along with most kids...
03-30-2019, 01:41 PM
#11
GM used this methodology in most of the TBI erra engines, some LT1, and the LAST instance of GM using the oil pressure fuel pump switch was in the late 1999's in the vortec 5.7L/7.4L trucks. After that, the oil sending unit only runs a gauge or is a transducer signal to the PCM.
03-31-2019, 01:50 AM
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At one time GM used a 12v+ feed to the oil pressure switch, and gray wire out going to the fuel pump. This WAS NOT a safety shut off, it was actually a BACKUP method of powering the fuel pump in event fuel pump relay fails. As long as Fuel Pump relay was working, fuel pump would continue to work with or without oil pressure.
GM used this methodology in most of the TBI erra engines, some LT1, and the LAST instance of GM using the oil pressure fuel pump switch was in the late 1999's in the vortec 5.7L/7.4L trucks. After that, the oil sending unit only runs a gauge or is a transducer signal to the PCM.
GM used this methodology in most of the TBI erra engines, some LT1, and the LAST instance of GM using the oil pressure fuel pump switch was in the late 1999's in the vortec 5.7L/7.4L trucks. After that, the oil sending unit only runs a gauge or is a transducer signal to the PCM.
