I tried to run a search on this the last couple of evenings, and am coming up with useful threads, but not all the info in one spot that I was looking for. If this is redundant, my apologies and, DMAG, just kill this thread. If it's helpful for anyone, though, here goes:
Ok, so you're riding, it's hot, your temp gauge is climbing at the stop light and you don't hear that lovely "Whrrrrrrr" of your fan. What's going on? And how do I find out where the problem is?
There are basically four areas where your fan can go kerplooey: at the fan switch (the little copper-colored nub that sits off the bottom of your radiator); at the fan motor (black, two-prong connector that links into your wiring harness on the left side of the bike); the relay (in the junction box); or there's something amiss in your wiring. The Haynes manual (page 3-4)offers a pretty clear description of how to troubleshoot, so here you go:
1 If the cooling fan isn't coming on, first check the fuses. If the fuse is blown, check the fan circuit for a short to ground. If the fuses are all good, however, disconnect the fan electrical connector (the two-pin deal). Using two jumper wires, apply battery voltage to the terminals in the fan motor side
of the electrical connector (that is, don't hook up the jumpers to the wiring harness). If the fan doesn't work, you've got a bad motor
and need to replace that.
2. If the fan does come on in step 1, the problem lies in one of the three other areas (switch, jbox, or wiring). Remove the electrical connector from the test area in step one, hook that connector back together, and proceed to step 3.
3. The Vulcan 700/750 has a single-wire switch harness. Disconnect the electrical connector (flat black connector, BK/Y wire) from the fan switch (again, copper-colored deal on the lower left of the radiator). Attach a jumper wire to the harness side
of the connector and ground the other end of the jumper wire to the frame. If the fan comes on
, the circuit to the motor is fine, but the thermostatic fan switch is defective
. You will need to replace the switch, or do a temporary work-around, as described further below.
4. If the fan still doesn't come on, trace the fan relay (in the junction box) - use the wire colors for identification and place your hand on it. Repeatedly touch the jumper wire to ground as detailed in step 3 above. If you feel and hear a clicking sound inside the relay, the relay is good and the fault must lie with the wiring. If no clicking is heard, your relay is faulty
and must be replaced
. Some Forum folks have been able to tear into the Jbox and replace the relay, but Haynes and others recommend replacing the junction box altogether.
Seems like lots of folks have bad fan switches at the moment, and rumor has it that they're expensive. A temporary work-around (thanks, liljd for the inspiration) is to hook up a toggle switch that allows you to control when the fan comes on. Attached the ground wire that would go to the switch to one lead on the toggle switch; affix another wire to the other lead on the toggle and ground this one. You can use those quick connectors (more color-coded ones!) to create this link up. Attached the toggle switch to someplace easy to reach on the frame, and you're good to go until you can afford a new fan switch. Just remember to turn it off after about 30 seconds - run it too long or you forget about it, and you'll have a burned out motor and a dead battery (probably in that order). Here are some pics of the toggle switch I hooked up this evening: Black ground lead from wiring harness is to the left; the bright yellow lead coming off the right is the ground connection to the frame; and the switch is affixed to the inside (lateral) of the engine guard via two zipties.
Hope this helps someone. And, again, if this is redundant info, just ignore me.