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Blue cod · Anmeldungsdatum: 15.11.2010 Beiträge: 14 Wohnort: England Status: **Offline**

I thought the voltage to the lights and fuel gauge sender unit would be the same, i.e. 12 Volts but it isn't.
Having transferred my heated grips from the old Suzuki 750 to the Gpz305, I was surprised to find that they wouldn't work when wired up to the fuel gauge or lights power supply. I was hoping to rig them up that way so they can only be switched on when the ignition is on.
Initially I thought the heated grips or switch had failed, but the red LED was lit on both setups. Contacting the Oxford helpline gave me the readings I should get at the switch and the resistance of the grips themselves. I should get 12.5 V at the switch but when connected to the lights got a reading of 10 V and only 5 V when connected to the fuel sender unit.
Should they both give 12 Volt readings and the fact I don't can be explained by old wiring giving a high resistance or are the readings correct?

Lothi · Verfasst am: So Nov 28, 2010 7:13 am Titel:

Hi Blue Cod

The fuel-sender gauge is not connected to +12 but to chassis (ground) !
At older bikes with mechanical gauge this must be due to security reasons (the helpline should have known this fact !)

The lights power supply (blue cable) has a seperate fuse !
Voltage must be equal to battery voltage when light is switched of !
If not check fuse-contacts and , - very typically for the gpz305 - check the ignition-switch !
Use wite acid-free vaseline from pharmacy as I proposed.
Very typically the ignition switch is corroded in most cases !
Unmount it, then You can open the switch and clean the contact-plate and grease it with lot of vaseline.

Corroded contacts/plugs are common for a 15-25year old bike, maybe used for daily business in the past.
But if given attention to that and checked all contacts in depht and protected with vaseline this will last the next 15-25 years Wink

If You have removed the tank please check the main-cable at the headset; often it begans to wear through at the metal holder there. By the way You can protect future wear by putting/wrapping a piece of (old) bicycle-tube between the metal holder and the main cable .
_________________
Grüsse

Lothi tach

Blue cod · Verfasst am: So Nov 28, 2010 10:13 pm Titel:

Indeed there are only 3 fuses in the fuse box on my bike. One is live all the time even when ignition is turned off and the front and rear lighting circuits each have their own fuse and are only live when lights and ignition switch in the on position.
On my Suzuki GXS750 there were more fuses and I wired the heated grips into one that was live only when the ignition was switched on.
Temporarily I've connected the heated grips to the main fuse(they work with that connection) but will connect it up using a 4 pin relay directly to the battery and something like the horn or brakelight which only works when the ignition switch makes it live. I don't want to forget to turn them off or more likely have somebody else turn them on when the bike is parked up and unattended....resulting in a flat battery!
I will also have to clean up the ignition switch in the manner you suggested.
Fuel gauge is working now(replaced sender unit) but isn't as accurate as I'd like.
Reading nearly empty after 110 miles(180km) having used a couple of gallons(9 litres) to fill the tank, I reckon it still had enough fuel in it to do another 70 miles(115km) before the tank is actually empty!

Lothi · Verfasst am: Mo Nov 29, 2010 8:14 pm Titel:

Hi Blue Cod
Glad to hear the news Smile

Avoiding empty battery:
You can use a Supply Voltage Supervisor /Batterycheck/Accu Saver/Battery Guard (or whatever this is named) for a secondary battery, mostly used in caravans to avoid an empty starter-battery. These circuit (relais) cuts off a load if voltage drops below an adjustable voltage. Something like "KEMO M148A"; this way You can connect it directly to the battery; adjusting it to 12,2V to switch off.

The fuel gauge will never be linear !
Even factory-made and brandnew it won't be linear; not a bit !
Running at the beginning, take a rest in the middle and easygoing the rest of its way.
But what You can trust on is the position: same position , same capacity.
After some refilling You will get experienced how many gallons remaining in the tank and which virtual fuel-level the meter is cheating You.
_________________
Grüsse

Lothi tach