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Discussion Starter #1
OK, my '04 998 Matrix is getting close to overheating when I'm sitting at lights just idling. My fans are not coming on. I noticed this problem just after I installed my Power Commander 3 USB (don't know if the problem is related or not). I tested the fans themselves by hooking them directly to the battery and they work fine. My guess is that it's probably the fan relay. So I'd like to know the following:

  1. Which relay is the fan relay?
  2. How can I test this relay?
  3. What's the likelyhood of the issue being related to the PC3?
 

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1. Fan Relay - as far as I know there is no fan relay, at least on a 996. Its connected directly to the thermo switch located near the thermostat.

2. Testing - unplug the connector leading to the switch and put a wire jumper in the termianal sockets, the fans should operate. Alternalty pull the switch connector and put a ohm meter directly on the switch, iy ought to read near zero ohms (closed) when the operating temps are > 200 - 220 deg F. .

3. PC culprit - not too likley; although it may be running leaner at idle which could increase idle temps.

Check for proper thermostat operation by noting when/if it opens and diverts coolant through the radiator. You'll know this by feeling the outlet line at the radiator, it should be near the temperature (hot) showing on the dash board. If it is only slighly hot then the thermosatat may not be opening fully.
 

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Discussion Starter #4
There's a fuse for the fan to check.
Forgot to mention that, but I did check the fuse first and it's fine. I also checked that the fans were securely plugged in.
 

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OK, my '04 998 Matrix is getting close to overheating when I'm sitting at lights just idling. My fans are not coming on. I noticed this problem just after I installed my Power Commander 3 USB (don't know if the problem is related or not). I tested the fans themselves by hooking them directly to the battery and they work fine. My guess is that it's probably the fan relay. So I'd like to know the following:

  1. Which relay is the fan relay?
  2. How can I test this relay?
  3. What's the likelyhood of the issue being related to the PC3?
not the pciii. Nees a bit of info to help you out. What is the temp indicated on the guage?, is the coolant tank at least at the low mark? what is the ambient temp when the problem starts?.I do not have a wiring schematic in front of me at the moment but i believe the fans on the 998 do use a relay they should always have +12vdc at them with the key on.There are 2 relays under the batt 1 is for the fuel pump the other might be the fan's.Easy test put the bike on a wheel stand put the kickstand up, turn the key on and you will hear the pump run, swap the relays and see if the pump stops working if it does not work the relay is bad.Those relays have been a HUGE problem lately they corrode and stop working or act up they are $8.00 each are used in a lot of models. 1 week i replaced 5 corroded or inoperative relays. If either relay shows any corrosion replace both. the ecu grounds the fan to operate them. check fuses first,then ground your negitive lead to your meter to the negitive side of the batt and turn the bike on and test for 12vdc at the wires on the harness side of the fan connector this will narrow it down.Also the temp guages have been known to read high. I have had a few 998's with cooling problems. the bikes would boil over in prolonged iddiling while in traffic in the summer. this occurs at 255f due to the cooling system pressure of @15psi higher pressure raises the boiling point. we had to put higher pressure caps on the 996 ama superbikes when we raced at pikes peak due to the high elevation.
I believe the fans come on at 215 or 217 and shut off at 213. Actual water temp not necessarly indicated temp.You can easily go to a dealer and have them plug into the ecu and manualy activate the fans with the ducati diagnostic equipment.Also have them read engine temp through the diag equip and see if the h20 guage matches and if not what the diff is. Ie 220 on guage is really 195.I had many people with st2's come in and coment that their fans did not work only to realize that the fan came on at 227 and they never got it that hot
 

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check all wires to and from the fans.
check the wires from the fuse to the fan.
04 bike, I don't know where you are located, but it could as simple as mild corrosion on a terminal.
 

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Discussion Starter #9
mr-x: The temp gauge starts out at just below 180 and rises to 250, VERY quickly when the bike is warmed up and idling. Coolant level is between high and low marks. Ambient temp appears to be irrelevant as the problem has occurred at temps ranging from 45 degrees F to 90 degrees F at about the same rate. I will try the fuel pump relay swap test and hopefully determine which of the two relays is the fan relay and hopefully that it's only a relay problem. All my wiring and connections look pristine. Bike only had just over 4K miles on the clock when I bought it a couple months ago, and besides the typical road dust everything underneath the fairs look brand spanking new.
 

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Sorry to hear about your problem. I installed a toggle switch to turn my fans on and off on the 998. The fans always seem to come on too late anyways. The switch along with the water wetter will cure any problems of getting hot. Did the same with the 996, that I still have for sale. I know you want to get to the bottom of it, but if it stresses you out to much just install the switch.
 

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Discussion Starter #11
Sorry to hear about your problem. I installed a toggle switch to turn my fans on and off on the 998. The fans always seem to come on too late anyways. The switch along with the water wetter will cure any problems of getting hot. Did the same with the 996, that I still have for sale. I know you want to get to the bottom of it, but if it stresses you out to much just install the switch.
I thought about installing a switch when you replied to my "How to test fans" thread. I'd really like to get them to work automatically as they once did, but if it becomes too much of a headache to chase down the cause then I will install a toggle switch. If it overheats after that it's because of the loose nut behind the bars.:D
 

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Sorry to hear about your problem. I installed a toggle switch to turn my fans on and off on the 998. The fans always seem to come on too late anyways. The switch along with the water wetter will cure any problems of getting hot. Did the same with the 996, that I still have for sale. I know you want to get to the bottom of it, but if it stresses you out to much just install the switch.
when you do this and throw the switch you back feed a ground into the ecu, it will throw a fan error code and if something does go wrong with this non stock wiring the ecu can sustain damage ecu's are $1700
 

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Discussion Starter #13
Update

I followed mr-x's recommendations (swapping relays) and everything ended up working. Fuel pump and the fans.



(Forgive my 4th grader graphic arts skills!)

I swapped over the two relays labled "1" and the "thing" below them (labled "2") appeared to be slightly loose so I reconnected the fitting.

I went for a test ride at lunch today and when I got back I idled the bike watching the temp gauge. It rose up to just above 210 and STOPPED! I killed the engine and the fans rans for maybe another minute, one fan stopped after a little bit of temp drop, and then the second fan stopped when the temp gauge dropped down to around 210.

I'm not 100% sure what fixed it (probably a loose connection) but I'm just glad it's fixed! Thanks for the help everyone!
 

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Hey Moto, will you please repost that link, as it doesn't appear to be working.

Thanks-Benjamin :confused:
 

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When I want to know what a cooling system is really doing, I get my digital multimeter out and use the thermocouple that came with it. I loosen the clamp where the top hose attaches to the radiator and slip the wire between the hose and the radiator nipple, then tighten the clamp back down so it doesn't leak. That way, I can read accurate top coolant temps and find out the temp at which the fan switch closes, and also track the thermostat operation.

One thing to keep in mind: If the cooling system isn't boiling, it's not overheating. With a 50/50 water/coolant mix and a pressure cap, the boiling point is over 240F.
 
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