Coolant temperature sensor modification.

[SIR tricky]

I hope this post might help others when they are trying to fathom out some of mother Honda's undocumented changes, at least I couldnt find anything and neither could the dealer.

According to the schematic for the 84 & 85 Aspencade the sensor (thermo unit) has two connection points. I think this applies to the later GL1200's also (86 & 87)



The 84 & 85 Interstate has one connection point



I found it impossible to have the dealer locate a sensor with two spade connections, it doesnt exist, only the single pin sensor is available.

Item 11 in the thermostat parts fiche.

I traced the wiring and one of the two spades was directly connected to ground, both wires were green but the one with the blue sleeve was the one that led to the gauge. That was the one that needed to be connected to the sensor. The body of the single pin sensor was the ground.



Looking at the schematic it shows the ground wire to be connected to the top of the T shape of the contacts, actually is was connected to the vertical.
Fortunately I did pull the sub harness apart to check which of the green wires had the blue sleeve.
The gauge reads correctly once again.

[admin]

I'm glad you got it working properly Tricky and thanks for sharing the experience with us. I love your meticulous detail it really helps to make things clear.

[Bill Davis]

Just returned from 1500 mile trip to the "dragon" Rte 129 Tenn/NC. In Robinsville, NC at the end of the day, coolant boiled out the overflow as the fan didn't turn on. A great local wrencher determined that the thermo switch was blown and there was no replacement part readily available so he wired a switch across it and I now have manual control over the fan. I understand its about a three hour job to pull the radiator and get a new thermo switch put in. Think I'll go along with the switch for awhile.

[Fatwing Chris]

Just don't gap out Bill watching the local talent and forget to turn it on.I wired a switch into my old 75 Wing because I liked to have the fan come on a little sooner.It's easier to keep it cool than it is to cool it down.I wired it in parallel with the stock switch just in case I got distracted(mine was still working though).

[admin]

Flex-A-Lite fans used to make a fan thermostat/relay combo with a temperature sensing bulb that would fit between the upper rad hose and the upper rad hose fitting. It had a wedge of rubber with a tapered slice in it. When the hose clamp put pressure on the wedge of rubber it would heal and seal and voila you now had a working temperature sensor inside your cooling system. I used it for years in my Corvette and it never leaked and the nice thing about it was that it was adjustable and it only cost about $35. You guys might want to look into something like that.

[T. Bix]

Take a close look at the connector to the thermo switch. I had a simular experience last year and it just turned out to be the pins in the plug had slipped back. If you push them back in they will at some point very soon just vibrate back out. The fix is to crimp on two new female bullet style connectors and plug those onto the posts of the thermo switch. It is possible that it is the switch itself but unless your bike was already heated up when he checked it he could have mis-diagnosed the problem.