Engine/Transmission (1998.5 - 2002) Fuel pressure idiot light wiring question

[mgoncalves]

OK, I want to have an idiot light that comes on when my fuel pressure gets low, until I can afford to get a real gauge.



I picked up an oil pressure switch that I think does what I need it to do, but I am not entirely sure how to wire it. For now it's mounted on the inlet of the vp 44 with a tapped banjo bolt. The book says the switch is a 2- 4 psi light type switch, I hope that means it will do it's thing when the pressure gets between 2-4 psi. Now, how do I wire a light to it? Do I run 12 volts to a bulb and then ground to the switch? Is it safe to ground to the switch if it's mounted to the pump?



I thought I had better ask here before I go wiring things up in case I am thinking backwards here.







Matt

 

[jkern]

here's how...

i did the same thing on my 99. make sure that you get a "normally open" single wire (blade or output) pressure switch. i use a NAPA 5psi 1/8NPT switch, but i can't remember the part number. i used a 12 volt LED from radio shack (they have one mounted in a black bezel with leads already on it for a couple bucks) i ran the positive wire to a electrical source that is hot only when the ignition is on, so the light won't be on all the time when the truck is off. and then simply use the switch to ground the light when it sees low pressure, which effectively completes the circuit and lights the LED. the ground simply comes from the switch being mounted into the metal of the engine and fuel system. this setup has worked great for me... but i give you one word of caution. mount the pressure switch before the filter on your 2002... the reason being is that the vibration of the truck and the pulses that the VP44 can produce will ruin the pressure switch in short order. by mounting it before the filter you get less fuel line vibration and pulsing, although you don't get as accurate of indication of what pressure the VP44 is seeing. my brother went through 3 of them on his 2002 before we figured out what the problem was. i hope this helps ya out, if not PM me and i can explain further,



-jeremy



sorry i couldn't post this sooner, i am at work and out network just crashed!!:{ :{

 

[mgoncalves]

Thanks, that's what I figured but I wanted to be safe and ask here first.



Matt

 

[Texas Diesel]

The LED must not see more than 2. 1 volts, it will burn out. You can add a 670 ohm resistor in series but Radio Shack has a LED holder that has a LED and resistor mounted in a holder, it's around $2, I can get the P/N tomorrow if you need it. Dont forget to use a small (1 amp) fuse where you tie into the +12V.

 

[jkern]

use the 12v LED!!!

i hate to disagree with ya, but radio shack does have a 12v LED that has the resistor built in the base in the bezel mount. that is why i suggested its use. i use this LED for my fuel pressure warning light and many other indicator lamps on vehicles. it works really well.



-jeremy