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Idiot Temp Light Stays on

3892 Views 15 Replies 4 Participants Last post by  DoBro
I purchased a parts bike to replace parts on mine. $600 for a 2003 Suzuki Intruder VS800GL that only had 4883 miles on it. I totally stripped it down to the frame. The only thing I saw wrong with it was one of the seals on the fork leaked. I used some of the parts on my bike and did a lot of wiring unplugging when I changed the handle bars. (Mine was bent from a wreck before I got the bike.) When attaching the wires back together again I came across a wire on top of the front cylinder that I found is a coolant sending unit. There is no wire color code that matches to plug it into. The is one wire that is long enough to reach it but the color code is wrong. Everything else electrical works just fine. I have a wire schematic but it does not help. Anyone know what wire it connects to? Sure could use some help. Will post images of my bike when I get the chance to.
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The wire from the temperature light control module (white module in indicator lamp housing) to the sensor is black with a green stripe (B/G). It also has its own direct wire to ground that is black/brown (B/Br).
Thanks WintrSol.

There IS a black with green stripe that is in the area to snap it to.


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That looks right; the only other B/G wire I can find on the schematic goes to the horn from the horn switch.
The service manual says the test to see that the module is working is to connect a 17 Ohm resistor from that B/G wire to ground, and the bulb should light. Since the sensor is ~28 Ohms at 100C (212F), a value above about 40 Ohms should not cause the lamp to light.
Horn works so that has to be it! I really do appreciate the help. Thanks again WintrSol. :) You came thru for me once more!
He has a habit of doing that
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WintrSol. I hooked those wires together and the light still stays on. To get to them I have to take both side covers off, take the seat off, take the fuel tank off and then the front side cover just to get to those 2 wires! Before I can check I have to replace the fuel tank to crank the bike to see if it goes out. Anything else you can add that would help get this issue straightened out?
Do you have a Volt meter with an Ohms function? If so, measure the resistance of the sensor to the engine; cold, it should be a lot higher than 150 Ohms, maybe over 200. Your thread title says the light is always on with nothing connected to the sensor; I would measure that B/G wire to ground, to check for shorts to the frame. The manual gives no measurements for the module, but I expect it would be higher than 200 Ohms to ground. The light panel is really crowded inside, and pinching wires when putting it together is very common, so make sure that tight bundle of wires is OK.

I don't recall that you need to start the engine for the water temp light to go out; the oil pressure lamp, of course. With the B/G wire disconnected, try turning the key on. If you set the run/stop switch to stop, you won't have the ignition powered, which should protect the coils, just in case the igniter turns one on. I think that the light should not be on, unless you connect a low value resistor (<= 17 Ohms) from the wire to ground.
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Yes. I have one. Haven't had time to follow your recommendations yet. Been building a welding trailer and got a Harley coming tomorrow to work on. Plus tomorrows my birthday. ;)
I do remember the light coming on when I turned the key but as soon as it cranked up it would go off. The fan comes on when it gets to hot sitting at a light. Could it be a faulty thermostat causing it?
I'll get back with ya on this sometime next week. Sorry for the delay time. Have a good weekend.
I seldom heard the fan on my VS800; usually after leaving an Interstate on a hot, windless day, or if what wind there was couldn't pass through the radiator. Facing a 5mph, or higher wind would cool it fast enough the fan didn't come on, or only briefly. Idling in the driveway long enough would make it run, though.

You can test the thermostat without removing it by starting the engine, and feeling for the heat to flow from top to bottom of the radiator, as it warms up past the point the thermostat opens. That said, any air in the system can cause the fan to come on early, as hot spots develop in the heads, and that over-heated coolant hits the fan sensor. You can check for air by rolling the front wheel onto a 2x4, so the radiator neck is raised the engine until you feel the radiator start to warm; rev it a bit to force any air into the radiator. Let it fully cool and take the cap off, and the level of the coolant should be at the top of the radiator. If not, top it off and repeat.

I never had my temp light come on when the engine was running; it could be the circuit is biased so that it comes on when the battery is at 12.6V or less, I just don't remember now. When the engine starts, that Voltage should jump up over 13V pretty fast, so if the circuit is set up this way, the light should go off. You may be able to test this by connecting a battery tender, and raise the Voltage. There is no other way the circuit can tell if the engine is running. After checking the wiring isn't damaged, that is.
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Sorry it took so long to get back. Been very busy those days!

Had a thought. Could I have the horn B/GR wire hooked up to the one that goes to the sensor and vice versa?
That thought came to mind while I was away.

I haven't had the chance to follow your recommendation as of yet.

(I now have an issue with my other bike, 2000 Kawasaki Vulcan VN800. Will post it in another thread latter. tho.)
Had a thought. Could I have the horn B/GR wire hooked up to the one that goes to the sensor and vice versa?
That thought came to mind while I was away.
It's possible, but unlikely. As shown in your photo, the sensor has a pin that fits a socket on the wire from the temp module, and that matches the schematic. The schematic shows a socket on the horn, and a pin on the wire from horn button. If the wire from the module could reach the wire the from the horn button, they would mate, but the horn switch is normally open, so the module wouldn't see the low resistance that would turn the lamp on, unless the switch is damaged.

I really think the wire from the module is pinched, probably behind the plate under the speedo/indicator panel.
Have been away all this time and got home yesterday. WintrSol. You were right. The wire had been pinched. It no longer stays on. ' You da MAN! :) Thank you so much. Issue resolved.
Hey, those pinched can be the hardest to find. Glad you didn't give up on it!
I just love it when a fix comes together. And a much better fix than removing the bulb. We did not have warning lights in the days of old. We knew the engine was too hot when: the oil drops from the cylinder head burned a hole thru our pants, or the engine stopped turning. But usually hot has a smell to it.
The ABS light stays on, on my Dodge Caravan, since I replaced all the calipers and pads. I am thrilled.

WintrSol. I am a, never gives up, never surrender, type of guy. :) And stubborn as all get out.

Mucho thanks!
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