My '02 Monster 620ie dark has been a terrific bike for the last three years, with almost no problems until just lately. Even now, it's still a terrific bike, and the problems are both minor, and don't effect the running of the bike at all, they're just annoying.
Anyway, a few weeks back I rode from my home in Norfolk VA to my parents in southern Maryland, about 210 miles each way. On the trip, I noticed that the engine temp readout would flash and fluctuate while I was moving. I don't mean by a few degrees, but would read 255, then blink and read 173, then blink and read 220, etc. The weird part is that when I came to a stop, engine running, the temp would stay steady, or fluctuate normally, going up a degree or two at a time. I checked the wiring to the probe in the vertical cylinder, pulling each connector, checking fit, spraying a little electrical grease and reconnecting, but it didn't solve the problem. Today is the first time I've ridden since then, and when I started up this morning, the low fuel light went on, even though the tank was full. As I rode throughout the day, I saw that the light would blink off every once in a while, only to come back on a short time later. The fluctuating engine temp problem is also still there.
Is there any way these problems could be related in some way? Any spot in the wiring that is common to both sensors?
I could just replace the sending units, and that's probably my next step, but I'd rather not do that only to find that the problems still exist.
Any thoughts?
As far as I know its not a common problem, but I don't know a lot (have only had the 620 for about 8 months, but been around bikes for a couple of decades). Without knowing any bike-specific trouble spots I'd suggest checking first that all the ground connections to the frame/engine are clean and tight. Second I'd check all that all the wiring harness connectors are clean and tight. I'd also wiggle each connector with the bike running to see if it makes the gauges go wonky. I had a problem with a suzuki last week where it'd randmonly loose all electrical power. Everything was clean, tight etc. After checking around I noted that when I wiggled one connector I could make it all come back or all go away. Turned out one of the copper connector pins was supposed to have a spring-loaded little tiny tab inside that kept pressure on the male part in the other side of the connector. That tab had broken and was laying in the bottom of the copper female pin. It all looked perfect unless you looked really super closely.
It seems a bit unlikely that the fuel sensor and temp sensor sending units would both go wonky at about the same time - I'm thinking a common ground or common harness connector is to blame.
Good luck!
What throws me off is that the temp malfunction only occurs when the bike is moving. It's fine sitting at idle.
The sender for your oil temperature gauge is in the plug for the oil screen. Chances are good the connector is loose.
With the key on (and the fuel light malfunctioning) lift the tank and disconnect the connector on the bottom of the tank. If the light goes out the sending unit is the problem.
howies on the money there, so incase your wondering the oil screen and thus oil temp sensor are in front of your right toe and under the oil level sight glass.
i think the conector is a little under engineered for the weathering it gets at that location as mine has faultered like yours in the past. its a spade type connector pushing over a flat disc like probe on the end of the sensor. i pinched mine to make it an extra tight fit on the end of the sensor and its been ok since.
Pulled and checked the connection to the temp sender, it did seem a bit loose. Tightened it up and that took care of problem one.
Howie, Doesn't that connector also provide power to the fuel pump?
Nope. If you disconnect that wire the only problem you will have is no temperature reading. Maybe you are thinking of the low fuel sending unit?