temp display of my v-tec is not correct and makes changes frequently!

Hello everyone, a few weeks is that the temperature of the display of my v-tec 2003 starts giving erratic and discontinuous values​​, increased from 60 to 81 to 75 to 60 degree, the display show a number for 4-5 seconds, sometimes swing between two numbers with about 10-15 degrees difference between them, then it all comes back after a period standard and follows the exact temperature of the engine! The engine temperature is running ok and I did this summer long journeys often above 500 km a day and never any trouble, have you got any idea of my problem?
I replaced this week thermostatic valve and temperature sensor thinking it was that and instead the problem remains, yesterday i finally changed all the instruments, speedometer tachometer ecc, nothing to do, the problem remain!
this video show the problem:

VFR Vtec Termometro - YouTube

Thank you so much if you can help me!

 

Hmm

As it seems unlikely that the replacement sensor you fitted will also be faulty, two possible causes of weird instrument readings spring to mind. (1) air trapped in the coolant systems, and (2) it could also be a warning sign of charging system issues.

Search on here for posts by Rubo on " the drill". A while back he set out the known issues with the early vtec wiring looms (melted connectors/bad earths etc/fried stator and RR issues) and then explains how to check the system health. I suggest you carry out a few checks with a multi meter and post up the results. With the battery disconnected - what is the battery voltage? If the reading is below 12.5v put the battery on charge and then repeat the check and again after 1 hour to see if the battery is holding the charge? If the battery volts look OK then check the volts with the engine running and at 5,000rpm?

Good luck - let us know what you find.


SkiMad

 

I know you are in Italy, but here in the US, there was a recall on a wiring harness for certain model years. 2002 to 2005? Not sure.

Anyway, I don't know if that's a "worldwide" issue, but thought I'd mention it.

Otherwise, I'm with Skimad on this one. The VFR's are known for electrical faults that might show one problem (such as your temperature), but the problem could be something entirely different. From bad grounds to a faulty regulator/rectifier, or R/R. You might want to read up on that and start performing the tests to check it out.

 

That is weird......All I can think of is faulty sensor
Have you check make sure all connectors are clean, completely flush the radiator?

 

If you are just starting the bike up, by the way the temperatures are reading, it looks like it may be jumping back and forth between engine temp and air temp. I noticed the higher temperatures were consistently getting higher at a rate you might expect of a cold engine warming up. The lower temperatures were consistent with your air temps are they not? But I also noticed there was no change on the symbol to suggest it was the air temp. That symbol remained indicating engine. When you have ridden it for a while, does it continue to do this? And if so, what are the temperatures like. Are the highs right up there and the lows still similar to what you may expect for air temperatures.

Something to think about until you determine what is wrong for certain.

Good luck.

 

Thank you all for the quick replies!
We illustrate better my situation.
I travel a lot with my vfr, this is my second VFR v-tec always of the same year 2003.
The last year I did a tour in the Arctic Circle and NordKapp and I traveled 13,000 km along the Norwegian and Finland coast.
At the end of the trip the thermometer of the temperature began to make frequent changes to these numbers.
So during this winter because the bike has 40000km I bought the stator, the R / R, the thermostat and the water temperature sensor and I changed the pieces (Home work with passion) and checked everything,
but the problem is still the same. so I think it's a problem with the wiring or grounding.
What do you think?

Thank you very much for your cooperation,
Lorenzo

 

Will you able to switch from Engine temp to outside temp to see if the display work? Just a thought my be the little sensor under the button need to be clean. Like Randy said must be wiring, button or sensor faulty.

 

Sensor was tested before installation, and yes, I can switch from engine and outside temp (outside temp is ok)...
I don't know how test the ground of the signal of the sensor, maybe sameone can help me in this test?
How can I check the ground of my vfr?

 

If you are confident the charging system is healthy (eg decent 15+ volts at 5,000rpm), the cooling system does not have an air lock, and the current ECT sensor is working, then you need to start by looking closely at the following wiring diagram



The gauge on the instrument panel takes feed from the open air temp sensor and the ECT (engine coolant temperature) sensor. The diagram shows the various places where there are connectors.

As bikes are subject to a lot of vibration and things can shake loose - even if a connector looks properly installed dont assume its fine. Over time a single connction within a multiplug connector may come loose and give rise to intermittent connection issues. Likewise water intrusion can result in increased resistance which may upset sensor readings.

I would start by carefully disconnecting, inspecting and reconnecting each connector on both circuits. Then clean the earthing connection which runs from the instrument panel via the grey connector to the green earthing point. If you find obvious signs of corrosion on any of the connectors, take your time to clean them and then treat with suitable protective spray for electrical connections. It is also worth cleaning the battery connections especially the black lead where it attaches to the frame - as this is the main earthing point on the bike.

Once you have checked the connectors, see whether the gauge is still giving erratic readings.

If the problem continues, you need to get out the multi meter and check for end to end continuity on each of the sensor wires - REMOVE the battery first. As you may be chasing an intermittent fault in the wiring, the first time you check the circuits may all seem OK. So you may need help to repeat the end to end tests whilst an assistant GENTLY flexes the wiring to see if that reveals whichever wire is giving rise to an intermittent fault.

Hopefully this will allow you to get the problem resolved and get the VFR out of the garage and onto those fantastic Italian mountain passes like Stelvio - where your VFR belongs.


Once you get the bike sorted post up in the Europe section and maybe we can arrange a get together - I am over in Chatel - France so an hour ride from St Bernards Pass and the Aosta valley.

Good luck - let us know how you get on.



SkiMad