Join Date: Apr 2005
Location: Guilford, CT, USA
NOT a Motronic guru
... and I did not sleep at a Holiday Inn last night. However, from what I can understand of the wiring schematic from the Clymer manual, for "2001-on LT Engine" there is both an air temp sensor (not the ambient temp thermometer) and a coolant temp sensor. Both connect directly to the throttle potentiometer (possible source of enriched mixture?) and to the Motronic via a brown/yellow wire at pin 22. Pin 17 of the Motronic connects to the Fan Relay via a blue/yellow wire. The air temp sensor in on the front of the air box, above and slightly behind the left radiator. It's plausible that that is the source of your problem. According to the Clymer manual, "The input from this sensor is used by the Motronic control unit to determine the air/fuel mixture and ignition timing for optimum performance." IIRC, on early LTs the air/fuel ratio was enriched in hot weather, causing the infamous "hesitation" when accelerating from a stop. Because I do not have the "brown wire" to snip on my bike (1999 LT), the next best fix for hot weather hesitation when accelerating from a stop was to unplug the air temp sensor completely. I did that, and it has eliminated the hesitation, with no adverse effects on any other function that I have noticed. If you have skinny long fingers and don't mind putting several of them out of joint, after removing the left side upper fairing it is just possible to get to the air temp sensor and unplug it without removing the stingray and dashboard and nose cone. Or so I'm told. I pulled mine when I had all the tupperware off.
However, I think it is more likely that your problem with the fans being triggered too early is due to a bad coolant temp sensor. According to the Clymer manual, "The fan is controlled by the Motronic unit, fan relay and the coolant temperature sensor." The fact that your fans come on early makes me suspect the coolant temp sensor. It is located on the oil/coolant pump, close to the oil temp sensor.
Clymer says only the MoDiTec at your dealer can test these sensors. You could unhook the air temp sensor and run the bike to see if that makes any difference; probably have to take the tupperware off on the left side, along with the dash and perhaps the nose cone, to plug it back in, though. If you remove the coolant temp sensor you will dump coolant on your garage floor and won't be able to test the bike, so that one probably does require a MoDiTec. Good luck!
'99 Canyon Red K1200 LT - Buddah Bike
Last edited by was; Jul 26th, 2007 at 2:20 pm.
Reason: to correct a mistake