hello all, i'm having alot of trouble finding info on a early 2004 sportsman 500 with 2 heat sensors, 1 on lower rad, 1 on cylinder, i have replaced the one on rad and put a new thermostat in and fan is still not coming on, have good voltage at fan connection and fan working good when bypassed.

first question please ? if i disconnect thermistor wire on cylinder sensor and hot light and fan do not come on, is it safe to say that sensor is defective and is the problem.?

second question please,? if fan works fine when bypassed ( connection jumped) do i still need to check relays,fuses, sealed bags or there would be no power at fan connection if a relay was burnt, corroded,
thanks in advance,

 

This models has two circuit breakers. One 20 amp breaker close to the battery for the main power,one 10 amp circuit breaker under the front panel for the fan motor. Check that you have power on either side of the sealed plastic pouch red wires.If not then it's probably the breaker that has shorted or has corrosion causing the fan wire not to have 12 volts.You can slice this pouch open to replace it. The radiator sensor provides the ground path for the fan to kick on when it reaches a certain temperature. The sensor on the engine is just the hot indicator for the dash light. You can get these breakers at any auto supply for around 7-8 bucks. Here's a new one versus a couple corroded ones. Plus sense you've replaced the thermostat,make sure you bleed the cooling system of any trapped air by leaving the radiator cap off and let the fan cycle on and off(once you solve that problem) several times. Top off the radiator and over flow bottle.

 

thank-you for the quick reply, tonight i checked the relay closest to the fan with the red/black wires, relay was fine, will check others tomorrow as this bike has 3 sealed relays, thanks again opt.

 

Can't remember 3 sealed breakers on this model,but oh well. The later 2004 model had solid state breakers incorporated into the ecm. I'd like to see pics on this to refresh the old brain.

 

wire placement not original i'm sure, fan was working fine when i bought the bike, <br/>all 3 relays are good ,must be thermistor, when i unplug it nothing happens, maybe its part of circuit.

 

 

im wondering also if maybe its my ecm , even if vin says early model, anything is posssible in transition years . no ? dealer checked vin over the phone and said its early 2004 model.

 

Early model shows to have the radiator temp sensor,the later 2004 model with the ecm doesn't have one. The black ecm on this model was recalled and replaced with a silver one like this one located close to the cdi module. Your model should have the regulator behind the radiator. Possible the radiator sensor is faulty even if it's new or the connectors aren't making good contact. Plus I've been telling folks the radiator temp sensor completes the ground path which is wrong.. The sensor when reaches a set temp(usually 190 degrees or so) closes the internal switch and allows voltage to pass to the fan orange/blk wire. The fan is already grounded.

 

Think the extra breaker was for the speedo itself? The previous models temp sensor on the head had one blue/white wire that was strictly for the hot light and went to the speedo display. The newer two wire connected sensor I'm not quite sure if that's its only function,but you can still test it and the radiator sensor the same way. Measure the ohms resistance when cold and drop in a cup of hot water. Resistance should drop rapidly. If either one fails to do so,even the new radiator sensor,then that could be the problem on the fan not kicking in if all else checks out. After you get the problem sorted out, you'd still have to go through the bleeding procedure again to remove all the trapped air and hopefully that time the fan will kick on. Also as far as pulling the connector and having the fan kick on,only on the efi models would the fan come on if I remember correctly.

 

ok tks again, i can't remember if i tested the new Caltric rad thermal sensor when i got it, LOL I'll let bike get hot than ill test it to see if current flows tru it. That way i save burping it. (: