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1993 Lift Pump Relay Upgrade, '95 Confusion

If you don't want the LP to self prime with the key on when the WTS is on, you don't need to worry about the center pin 87a on the relay and it doesn't matter which pins (30/87) you use for the main battery power.

for relays that have a built in diode between 85 and 86, the relay only works with the ground pin 85 and trigger(+) pin 86. this only prevents feedback into the circuit that provides the trigger when off that sometimes can keep the relay triggered if other things are on that same circuit.

notice the pic here showing the built in diode on the coil side of the relay. also notice that the diagram shows pins 30 and 87a are in contact (normally closed) when the relay is off.

1744077804107.png

with using pin 30 as the one to the LP and 87 to battery +. this means if you apply power to pin 87a from the GP controller with the engine not running (ops has no oil pressure) the LP will turn on. Once the OPS sees oil pressure and triggers the relay, it then switches from 87a to use 87 to feed pin 30 and keep the LP running with the engine.

Hope this helps.
 
as for a solenoid to "bypass" the GP controller for longer glow time overide. you can use any old fender mounted starter solenoid.

This one from Napa would work fine.

1744078841355.png

the two larger terminals would run to the large terminals on the GP controller and one wire from the small terminals to a push button switch in the dash with that switch powered from and ignition power source.

remember this is essentially the same as taking a screwdriver and shorting across the two large terminals on the GP controller to run the GP's longer. if your GP run time is not an issue, none of this is needed.

on the newer 95+ GP controllers this is also not needed, splice into the yellow wire on the GP controller and run it to a push button in the dash. much simpler.
 
On the relay- understand a relay is for medium power and solenoid is for larger power use.
I disagree any old solenoid- I’ve seen guys use some that only lasted a year or so.
Get heavy duty/ constant duty rated ones. Like older semi trucks used for their lighting circuits.

If you’re GP relay is still working & you don’t mind it, I would suggest adding on the solenoid Leroy sells for it.
 
dbrannon79 said:
Oh, your referring to the relay mod for the ops and LP for the standard relay not the factory GP controller. those relays don't care which is the power in or the device being powered (30/87), nor for which is ground and trigger (85/86) that is so long as the relay doesn't have a built in diode.

some do have a built in diode between pins 85 and 86. but lets not make it more complicated.

the golden standard is to use pin 30 as the main power input from the battery and 87 as the controlled device output. pin 87a (center pin) is always in contact with pin 30 until triggered, then contacts with pin 87. some diagrams will show it the other way around and in some cases is needed when using pin 87a for different applications.

in the case of using one for our OPS to LP mod. we can wire it with pin 87 as the main power input and pin 30 going to the LP. this way you can run a wire from pin 87a to the GP controller (side that sends power to the GP's) so when the wait to start light is on, the GP controller is sending power to the LP for those few seconds to prime the system since pin 30 and 87A are connected when the relay is not triggered. This is were I mentioned needing a inline diode between pin 87a and the GP controller terminal so when the relay gets triggered and pin 87 and 87a are contacting, power is not fed back into the GP's from the relay.
Click to expand...
Could you give us a link to the relay with the built in diode?

I always used 2 relays, because I never quite got the whole diode thing.

Some people were installing diodes in the wire itself. I never knew what to buy or saw anything like an inline diode, similar to an inline fuse.
 
Here's the jungle site with some with diodes built in.


keep in mind that depending on what you use the relays for, you might still need an inline diode on the supply power or on the device the relay controls.

Here is a link to those too...

 
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dbrannon79 said:
Here's the jungle site with some with diodes built in.


keep in mind that depending on what you use the relays for, you might still need an inline diode on the supply power or on the device the relay controls.

Here is a link to those too...

Click to expand...
Thank you very much
 
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