Temperature gauge on cluster no longer works - 84 VT500

[osharke]

Fellow VT500 Owners. First the bike, 1984 VT500.

My temperature gauge on instrument cluster no longer works. The radiator fan works just fine it's just the temp gauge no longer moves. I have some ideas (replacing the fan sensor switch and or cleaning) but before I go taking things apart, I thought I would ask the forum if they have run into similar issues and what they did to resolve this. Thanks for your time and assistance.

-osharke-

[Bucko]

Bypassing the sensor should tell you if it's the gauge or the sensor.

[osharke]

Great 👍 tu. Are you suggesting to disconnect  the sensor from the switch and short it to the  ground? Then I would think the temperature gauge (once turned on) should move all the way to the right?

That would certainly be away to see what is working and what is not. I will say disconnecting the wire from the sensor is going to be problematic as it is in a tight snug area.

[osharke]

Forum -- can the OEM temperature gauge simply be replaced with another one (37450-mf8-0080). That is, is the temperature gauge sealed and therefore cannot be replaced? I was thinking instead of purchasing the whole instrument cluster ---  if  the part can be replaced, it just makes more sense (cost savings as well). I would think this would be doable seeing as there is a part # for the OEM temperature gauge, I was just wondering is this is true or not. So to summarize:

(1) has anybody repaired their temperature gauge by hiring an electrical nut and having the resistors replaced?
(2) is the temperature gauge sealed and therefore cannot be replaced? That is the only solution is to buy the entire instrument cluster?
(3) seeing as there is a part (37450-mf8-0080) for the temp gauge, maybe it's a simple as just opening it up, gutting the old and putting in the new. Is that true?

Of course there is the other option, TrailTech https://www.trailtech.net/tto-1 as another resolution --- which just might make the most sense.

Let me know.....thanks forum.

[murdo]

If the parts sheet shows the temp gauge as a seperate part then it can be replaced.
Interested to know how you tested the gauge to confirm that it was stuffed.

[osharke]

Couple of ways that I was able to diagnose the temp gauge -- my mechanic also confirmed my tests.

(1) Multi-meter no register; nine volt battery at the end of the temp gauge -- no movement as well
(2) Disconnect temp gauge from thermo sensor switch then short it to the ground -- no movement of temp gauge
(3) Replace thermo sensor --- same results with temperature gauge --- no movement

She is kaput.....

[murdo]

Thanks. I'll try that idea next time.

[osharke]

See attached, here’s what part 37450-MF8-008 looks like ready for install. If it’s doesn’t work I have a backup plan — I’ll just swap out the whole cluster, I have that as well. Forum if the temp gauge 37450-MF8-008 part works, then I will not be needing the cluster and it will offer it first to this group.

[RobertP]

Hi, here is what happened to mine .... When I got it, it was a basket case, apart from all the other issues, yes my temp gauge did not work. I took it apart and found the Bi-metallic strip had broken in half, that's the part that makes it work. As I am a qualified Instrument tech, easy, buy a cheap, modern, 2" temp gauge from Ebay ($9.29 AUD). Pull the old one out and toss it, install new one (with the sensor it came with). Had to modify the plastic instrument case for the new one to fit, drill some new holes and I removed the half bezel so could see the entire new gauge, only thing is it was sideways (same orientation as the std gauge), but at least it had numbers on it which I checked the calibration and was quite accurate. Here are some pics...
Pic 1. getting ready to pull all apart, you will be able to find new gauges like this all over ebay (Chinese)
Pic 2. both movements removed, you can see the difference, if you understand the technology you can tell the age.
Pic 3. installation complete.
I think I may have also had to play around with some of the internal barriers so the background illumination lights did not interfere with the speedo.
As I said I am qualified to do this, been doing it all my career so it was second nature for me, sounds like you indicated you might need someone to help, unfortunately I am in Australia and you are probably in north America somewhere.
I think I stayed with the sideways orientation because 1 or 2 of the holes for the terminals lined up and I only had to drill one more maybe, was some time ago, but with a little more work you can get it to sit properly.
So if you are prepared to go ahead with it Yes it does work. Good Luck

[osharke]

Thanks great information.  Question per your pictures it looks like you performed the work with the cluster intact and not removed. Is that true? Did you simply removed the top cover and remove/disconnect the temperature gauge from that vantage point? As I have the exact part I would hope it would be just as simple as a swap and off I go. Let me know if my pedestrian view is correct or not. 

[RobertP]

There were so many little details I would do without even thinking in this sort of process, Yes I did remove the entire cluster and take it out of its black case, as the wire terminals on the back have small nuts & washers on them. That means removing the trip meter knob off the left side, using a small (Jewellers phillips screw driver). I just had a look to confirm this as I currently have it off again (for good) as I am retro fitting  a complete new assembly Off a 2007 VTR250, all gauges and dash including lights, currently in the process of replacing all the black square plastic stuff with nice shiny rounded chrome including headlight, indicators and brackets. If you are just replacing with an original OEM gauge movement then it should be simple, just take your time, remember or even write down each step you do, keep things in order. There are lots of little nuts, bolts washers and screws so good to keep them in little separate boxes. There are 8 little Allen head screws holding the front on the box, these need to come out and as they are old bikes if they have not been removed recently they may be a little tight, so just grit your teeth and give some force they will free up, when they are out you can clean up the threads and apply any sort of lube/grease to ensure they do not bind up. There is a white rubber gasket between the front and the box /Gauges, this sometimes deteriorates and start to fall apart and sticks to one or the other so just be careful, maybe use a small screwdriver to ply it away from gauges as it is removed. Cheers and good luck.
Feel free to ask more questions, mine is out at the moment and I can have a look. I check my messages every morning here, you may even want to email Robert_piper@bigpond.com might be quicker if it suits. I have attached a pic of what I am installing.

[JACoH]

Hey RobertP, where did you find the cluster assembly in the attached pic? It says Honda on it, so the cables should hook up OK, I see it is KPH, tho. My cluster looks like it went over a cliff, and the needle is missing off the tach side, although I am thinking of using one off of a humidity gauge.

[RobertP]

I know what you mean about the gauges deterioration, both my pointers fell apart (I made new ones out of a can of Canadian Club) and the temp gauge broke in half amongst other things.
I got the gauge off either ebay or Aliexpress ( I could go back and check) just search for "Honda 2004 VTR250 gauges" there are many sellers in China, I bought the cheapest ($91.00 AUD) and the only reason I got this one is because it has the look/style I want.
WARNING ! it maybe for a honda but a completely different animal than our Ascot. It is NOT "Plug & Play".
The only thing that plugs straight in is the speedo cable. I am still installing so it has not been road tested, I am confident it will all work once I have completed the job.
It is in KPH because that is what we use here in Australia (and is required by Law) so it suits me.
The tacho does not work. As the Ascot is mech driven tach, that has to be done away with. This new tach turns out (after extensive testing) to be a simple 0-12VDC meter (which do not read a tach/sig frequency), I can only conclude the VTR250 sig is connected to a CPU which inturn sends a DC 0-12V to the meter. So I purchased another cheap ($14) retro Café 2" tacho off ebay ( these work of the ign/spark signal), pulled everything apart and transplanted the movement from one to the other.
This is just the start, then there is the temp gauge and all the wiring/lights issues, a lot of re-wiring had to be done to get every thing to work. Then all the mods and bracket fabrication to the triple clamp to make it fit in the right position, all that will have to be another post.
So unfortunately, this gauge set is wack it in and connect a plug, there is a lot of work if you are prepared to.
Maybe the instruments from a VT500C as they are the same bike but the old retro style might be for you.
I hope this helps, cheers, I will post more when it is up and running.

[osharke]

Quick follow-up, the replacement temperature sensor 37450-MF8-0080 worked like a charm. It wasn't all that bad to replace, just as Robert indicated take your time and mark everything --- especially as I was in unknown territory.  I was very luck to find a brand new part in North Carolina of all places. On that note, don't (if you can't help it) buy a used one from a junk yard. I tried that and it just didn't work. If you need a new one, I believe CMSNL (Europe) still has them.

Yes my "little red" is fully operation again. Life is good!