On the 88-90 trucks, we have a one-wire oil pressure SENDING UNIT down by the block that feeds info to the computer, and ultimately to the gauge. Also, we have a 2 wire Oil Pressure SWITCH up on top of the engine beside the distributor, which supplies power to the fuel pump whenever there is oil pressure. The lower SENDING UNIT sends all of the info to the computer and gauge, so the SWITCH isn't needed for any of that. My question is this, is there any downfall to leaving the upper SWITCH unplugged? Everything I can find about it shows it as simply being a backup failsafe for the fuel pump relay, as it supplies power to the fuel pump parallel to the fuel pump relay circuit. I have been driving for weeks with it unplugged now and haven't noticed any problems yet. The only thing I was thinking about was that it may put more load on the fuel pump relay without the extra source of power going to the pump, causing the fuel pump relay to expire prematurely.
Backstory on this, I am building an isolated second battery circuit for my truck, and my plans include using the top Oil Pressure SWITCH to supply a ground for a relay in the charging circuit for the second battery, so the second battery is connected to the electrical system when the engine is running, but will be isolated if it is not (key gets left on, lights get left on, etc).
Any input is appreciated.
Backstory on this, I am building an isolated second battery circuit for my truck, and my plans include using the top Oil Pressure SWITCH to supply a ground for a relay in the charging circuit for the second battery, so the second battery is connected to the electrical system when the engine is running, but will be isolated if it is not (key gets left on, lights get left on, etc).
Any input is appreciated.
