tempeature gauge problem

[fonnyfth]

Hello everyone on the message board I have a problem...maybe someone knows the answer.
After changing my instruments(a very nice one from my parts bike) my temperature gauge climbs straight to the maximum when I turn
the key. Did I do something wrong with the wires ?With the old instruments the temperature
gauge worked.

[toystoretom]

The temp gauge has a small heater that warms a bi-metalic strip (much like a thermostat) that makes the needle move. If the needle shoots right to "hot" you have something that is making that heater hot very fast. If I remember correctly there is a small unit that drops the volts down to 7 volts from 12 that supplies the heater. If somehow you crossed wires and were supplying 12 volts to the heater that would be a problem. Also, the other side of that circuit is a ground that controlled by the temp sending unit down by the thermostat. That almost sounds like that wire is shorted to ground. I'll bet you have some wires plugged into the wrong sockets. I would check it out fast before you burn up the heater in the temp gauge. The service manual has some info on all of this and a wiring diagram.

[fonnyfth]

Thanks Tom,
Found the faulty connections and everything is working fine.

[kanonkopdrinker]

I hope this is the correct thread to pose this .....

Rode around the M25 on Saturday last (the London orbital motorway) around 75-80mph -ish .... no problem.

Pulled off onto smaller A roads and noticed the temp gauge began to climb past the central line, where it sits most of the time.

The needle approached the red zone, but still the fan did not come on.

The engine did not exhibit any of the normal signs of overheating (loss of power, boiling over, nasty noises etc) and continued to sound and respond okay.

After arriving home and allowing it to cool overnight, checked coolant level. That was fine.
Taking it out for a spin today, after around 8 miles, again the needle was getting to the red zone.
Back at home, I shorted out the terminals on the fan switch and can confirm the fan is working fine.

Has some mentioned there is a little widget that knocks the voltage to the temp. gauge down to 7v and that when this fails, these are the symptoms?

If so, where is it? And where can I source a replacement? I will try this first, unless someone has a better idea?

Many thanks in anticipation folks!

David

[Jess]

David,

There is an ICVR (instrument cluster voltage regulator) that will fail. It is ref 28-19 P/N 34480-37600.

I am sure that I have a few somewhere if you can't find one.

Best,

[timpa136]

GoAndy did some excellent investigative work here.

re5rotary.proboards.com/thread/2089/new-voltage-reg-temp-gauge

Alternatively, Mopars had a big problem with their 7v regulators for their gauges, 1968 era. if I recall correctly.

Tim

[re5rotary]

Hi David perhaps buy or borrow an infra red temp gauge, these hand held devices are very cheap these days, and use it to read the temp of the radiator to see if the engine is really hot or the gauge on the bike is giving a false reading regards Terry

[kanonkopdrinker]

Thanks Terry.
Can anyone give me an idea what sort of temperature one should expect the the top of the radiator of a bike just having been on a decent run?
And where on the engine would be a good place to take the temp? The water pump housing?
David

[re5rotary]

You would like to think the radiator temp would be just above the thermostat opening temp plus or minus a few degrees especially after a run. It would be interesting to compare the temp guage reading at the point the thermostat opens, you would feel the hot water come through the top hose and I would expect that point to be maybe just below the middle of the guage. I think the water outlet where the temp guage sensor is would be the best place to check on the actual motor itself. regards Terry

[goandy]

Still reckon the best way is check the temp gauge & sender unit as per the service manual, check the resistance etc at 88 degrees. The entire procedure is described. I did that then also set my DC-DC converter to give the exact meter reading on the line at a simulated 88 degrees C.

[stevep]

I had to replace P/N 34480-37600 a while ago - I found 2 out of 3 NOS units I had on hand (that had never been used) were faulty.


The testing instructions in the manual identified the 7V regulators as faulty.

Steve