Join Date: Sep 2010
Location: Jacksonville fl
Do you have a schematic for the cooling system? When your having electrical issues a schematic is a must or your just guessing at what to check. Makes it so much easier you know exactly what wire does what and how the circuit works.
From what I see there is a fan relay inside the JB, it acts like a switch between the fan and the battery via the 30AMP (main)fuse. For that relay to operate it needs a 12VDC source and a ground. The relay gets it's 12 volts inside the JB and is present all the time, and gets it ground via the Fan switch (Temp Sensor). So the fan switch doesnt supply the ground to the fan it supplys the ground to the relay. The fan connector blk/yel wire is a ground and it should have a ground all the time. The blue wire is the 12VDC and goes to the JB. The blk/yel wire on the fan switch goes to the JB. Hopefully this helps out a bit.
Last edited by ifixf18s; 04-22-2012 at 07:36 AM.