sweet99ss

iTrader: (41)

This relay looks very simple I just have one question. There is a wire right best the positive wire that you hook to the alternator that says "Battery Negative".. I guess I'm just confused why this is right next to the power wire that comes off the alternator?

Does this have to go to the negative side of the battery or can I just ground it to the body or engine? If it does need to be used I will have to cut it and extend it to reach a ground from the alternator...

JakeFusion

iTrader: (7)

I'd have to go look. I believe I ground mine to the body. It's been about 3 years since I did it. But it's definitely not ground to the battery.

pdxmotorhead

I've seen some motor devices like that(Water pumps, fuel pumps) that want the connection to be at the alternator end ,, it helps keep noise down in the electrical system, then you can ground to the alternator ground lug as well..

JakeFusion

iTrader: (7)

Well the wire to the alternator is because the stock wiring can't support the 20A pull that the pump can draw efficiently. It has it's own in-line 40A relay. So you get the added benefit of the noise suppression with the additional juice.

ScottyBG

I believe that ground is for the relay. It wouldn't need to go the to battery, but it does need to be grounded. It is used to close the relay when the small lighter gauge red wire on the other end of the harness goes hot. The lighter gauge wires in a harness like that are always the ones used to trip the relay, and the heavy gauge wires are the ones that carry the main current to the device your intending to control with the relay. The signal current flows through that light gauge red wire to the relay, then out through that "battery negative" you are concerned about. This current is what would activate the relay. Without it grounded it will not complete the circuit, and the relay will not close, and thus the fuel pump wire will not be hot. The outer housing of the alternator would work, or anywhere on the head around there would also work, to avoid having to extend it.

sweet99ss

iTrader: (41)

Thanks for the info. I'll just have to cut the heat shrink and pull the ground out of the loom a little. Then run my wire off my hobbs switch to the activation wire..

And just double checking the "redundant pump and relay chassis ground" goes off the body straight to the fuel pump right?

ScottyBG

I never noticed it until now. BUT! You know they have mislabeled the diagram. The one that says "redundant pump and relay chassis ground", needs to go to the battery, or a very high quality ground. The little one, that says "Battery Negative" is the relay chassis ground, and can be grounded just about anywhere there is a ground, it doesn't carry much current. However the heavy gauge black wire will carry the same current as the big red wire, it is the return side of the fuel pump circuit, it should go to the battery, or some other place there is a ground capable of handling high current. By the looks of it, it is too short to go to the battery, so I'd grind off a spot on the frame, cover it in dielectric grease so it doesn't corrode, and anchor it there with a bolt, or sheet metal screw and washer, see photo below of my primary fuel pump grounds. I grounded them to the hex cap screw that holds my one relay there. I drilled and tapped a hole into the frame, and ground the paint and rust off for good contact.






Maybe someone from Racetronix will chime in and confirm, but I'm confident the diagram is mislabeled. If not mislabeled, confusingly labeled at least.