new wiring harness - what needs a relay?

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bkvail

Well-known member
Joined
Jul 16, 2011
Messages
243
we are installing a new wiring harness (21 circuit harness from speedway) and instructions does not cover installing any relays except for the engine fan. What other things will need a relay?

36 Diamond T cab
1st gen 12valve cummins 6BT, 5 speed manual trans
air ride (air compressor and battery behind cab)
no electric seats, no electric windows, no A/C - probably not even a stereo. I will have a USB and then all the normal things (lights, fog lights, wipers, heater).
 
Air compressor. Headlights. Fog lights. Horn. Lift pump (if the Cummins uses one).

I'll leave the rest for you to sort out. Relays are good for everything and anything with high amp draw, so the switch doesn't have to carry the load...

.
 
Air compressor. Headlights. Fog lights. Horn. Lift pump (if the Cummins uses one).

I'll leave the rest for you to sort out. Relays are good for everything and anything with high amp draw, so the switch doesn't have to carry the load...

.

the cummins has a fuel shut-off solenoid - that I just found needs a 70-80 amp relay.

thanks for your help though - had forgotten about horn needing one!
 

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