Temperature Sensor???

[beeroux]

Anybody know where on the bike the temp. sensor is?

Thanks,

GZ

 

[Ignacio]

Just to be clear, you're talking coolant temperature sensor on a Gen I and not the air temp. sensor on a Gen II?

If so, I wonder if it's the "Thermosensor Assy" on Electrical 1 diagrams, #16? Puts it under the tank somewhere, but I haven't layed eyes on it. In autos they're usually where the radiator hose connects to the engine block.

 

[otrfjr]

Just to be clear, you're talking coolant temperature sensor on a Gen I and not the air temp. sensor on a Gen II?
If so, I wonder if it's the "Thermosensor Assy" on Electrical 1 diagrams, #16? Puts it under the tank somewhere, but I haven't layed eyes on it. In autos they're usually where the radiator hose connects to the engine block.

My service manual for an 06 shows that the "thermistor" is located under the display/in the front cowling (diagram on page 2-63). Why couldn't they just call it an ambient temp sensor?

 

[beeroux]

Oops.

Yea, I'm talking the water temp. sensor that turns on the fan, on a Gen. I bike.

Whenever I can find the wire that grounds the sensor, I'll tap that ground, run that through a switch to ground, then I can turn my fan on at 2 bars when I'm crossing a border or stuck in serious stop and go outside of California. That will help keep the bike cooler without getting really hot first.

Pretty cool idea, no?

I'll do a write-up when I figure out whats what. Stay tuned.

GZ

 

[otrfjr]

GZ,

Please do the write up & let us know what type of switch you use.

Oops.
Yea, I'm talking the water temp. sensor that turns on the fan, on a Gen. I bike.

Whenever I can find the wire that grounds the sensor, I'll tap that ground, run that through a switch to ground, then I can turn my fan on at 2 bars when I'm crossing a border or stuck in serious stop and go outside of California. That will help keep the bike cooler without getting really hot first.

Pretty cool idea, no?

I'll do a write-up when I figure out whats what. Stay tuned.

GZ

 

[Ignacio]

Pretty cool idea, no?

Worked for my Rabbit years ago.

Don't know what they look like for sure, but it might look something like this typical auto coolant sensor screwed into somewhere in the head.

 

[twowheelnut]

There are two assemblies, one under the seat and one under the tank, presumably tapped into the coolant stream somewhere. The parts fiche doesn't connect the electrical bits to the cooling system, so it's hard to say and like Iggy, I've not seen the little bugger. It'll still go to three bars, but that's still cooler than four.

Look for items 16 & 18:

 

[beeroux]

OK, I did find in the manual the sensor thats under the T-Bar somewhere. Digging now. Unfortunately it gets complicated because the computer reads 3 or 4 bars and turns on the fan, so I gotta find a way to not hurt the computer in this process.

Stay tuned,

GZ

 

[FJRottie]

IIRC, the fan is small and at the top half of the radiator.

Would it be easier to add a small fan near the bottom half with a separate switch you control?

One bracket, one fan, some wire, and a switch.

That will leave out any mishaps when tinkering with the puter and sensors etc.

Just a thought.

 

[rangerray]

The sensor is threaded into the right hand end of the assembly (right where the label #24 is) in the diagram that shows the water pump, etc. You have to use a new o-ring upon reassembly. I've looked at mine a lot the last few days as I'm having to remove the entire assembly to replace the o-rings at the cylinder head. I hope, for your sake there's enough room to fiddle with the sensor without having to remove the entire assembly.

 

[Warchild]

Whenever I can find the wire that grounds the sensor, I'll tap that ground, run that through a switch to ground, then I can turn my fan on at 2 bars when I'm crossing a border or stuck in serious stop and go outside of California. That will help keep the bike cooler without getting really hot first.
Pretty cool idea, no?

I urge caution here. I used to be of the same opinion and thought this was a good idea back in the early-mid '90s on my 420-watt ST1100... until a grizzled old LD veteran by the name of Ron Major taught me otherwise. The same concepts he spoke about then still apply to the FJR.

The FJR's radiator fan turns at 3300 rpm and consumes a somewhat noteworthy amount of wattage (which is why it has a 15-amp fuse, where most other FJR circuits run a 10-amp). Running a watt-sucking fan more than called for by the cooling system will simply tax your electrical system just that much more.

Admittedly, this is no big deal if you do this on a infrequent basis. But still....

Just keep in mind that during the warm summer months, the bike is perfectly fine running at three bars on a continuing basis. That's totally normal. When you get into traffic or otherwise get into a situation where it goes to 4 bars, the fan is suppose to switch on and run anyway. So you really haven't gained any significant advantage by installing a switch to over-ride the normal system.

Install it if you feel the need, but I would just let the cooling system do it's job. If you constantly find yourself in stop-n-go traffic during triple-digit summer temps, well.... the FJR is just not a happy bike in these conditions.

As long as you have at least quasi-decent airflow when riding in brutally high ambient temps - say, 30-40 mph, thereabouts - the FJR is a lot happier.

 

[racer157]

If your desire is to have a separate manual switch simply tap in at the fan plug and go to your switch. There will be no problem because even if the bike turns on the fan thru its rather involved path of wires and relays there is no danger of hurting the relay that is used by the bike. I would however recommend you tap your power for the switch from a switched power source not directly from the battery. I also recommend you have a visible ***** light that comes on when the switch is on. Or you can just use synthetic oil and enjoy a cooler running engine. I have never seen 5 bars on my temp guage even sitting in traffic for 10 minutes. Have fun and keep the rubber side down.

 

[Constant Mesh]

The simplest way to add a switching device would be to connect to the fan relay wire as it enters the ECU under the seat. The relay coil is powered from the Ignition fuse (10 amp). The coil's return wire (green/yellow) is switched by the ECU. The ECU grounds this wire to switch on the fan. You could easily add a switch back near the ECU area to ground this wire.

Still a dubious idea at best.

 

[racer157]

The simplest way to add a switching device would be to connect to the fan relay wire as it enters the ECU under the seat. The relay coil is powered from the Ignition fuse (10 amp). The coil's return wire (green/yellow) is switched by the ECU. The ECU grounds this wire to switch on the fan. You could easily add a switch back near the ECU area to ground this wire.
Still a dubious idea at best.

I agree, but to each his own.

 

[beeroux]

Warchild, via his late mentor Ron Major makes a valid point. I had never realized the fan used so much juice.

Still, if the bike gets hot the fan comes on, so the juice is still being pulled, but this farkle may allow for the bike to remain cooler from the get go. And I can always decide not to use this option. It is switched.<G>

I'll think hard on this one, but I'm not against the idea yet.

Thanks all for the warning.

GZ

 

[IndianaTom]

Is there a thermostat valve in the cooling system? (One that closes when the engine is cold, and opens as the water warms) What is the temperature that valve opens, and the temperature the fan comes on? Does that change the need for a manual switch?