Hi all,

Firstly I would like to say hi to all from Australia and thankyou for welcoming me to your forum.

Now down to my electrical problem.

I have recently fitted a BMW fuel and temp gauge to my 1987 K100RT after mounting the gauges building a wiring loom and ensuring that the correct wires were matched with the plug under the tank. I decided to give them a little test to see if the backlight would illuminate prior to putting putting the tank back on and all the trimming. Lucky I did because I had a short somewhere and the wiring at the plug under the tank started to melt and smoke, specifically the earth (brown) and (Grey/Blue) running to what apears to be ignition wires.

I should note that the sensor wire for the temp gauge was not conected, I have yet to purchase the temp sender unit and install that part.

I imediately disconnected and start to ponder my situation.

Has anybody got any suggestions on what may be causing my problem?

How to test the gauges?

Regards,

Col

Hi Col,
I suggest you check with an ohm meter and see where the short is. If you look at the gauges they are very simple devices are you using an installation manual for the gauges?
Regards,
K-BIKE

can a temperature gauge be retro-fitted to an 85 K100RT? Something about just a light doesn't give me reassurance about high temperatures. Or is there some sort of backup alert to tell me the fan died (or coolant is bad, or water pump died, or etc etc etc)?

I check the ETK, and BMW has an extra water temperature sensor for the the gauge. The part # is: 61-31-1-459-197. Cost is $40+

I just added to the download section Bob's BMW parts list. This list has not been updated since 2005 and the indicated prices are just a reference.

On an '85 K you'll need a few things: The temp sensor, which replaces the drain plug in the waterpump; the piece of wire loom that goes from the sensor to the cable loom under the tank and then you'll need to find something to connect it to the gauges. I have done it, but as the loom of that year is not prepared for the gauges you'll need to do some wiring yourself or try to get a piece of wire loom for the three pin extra equipment plug under the tank. So yes it can be done, but is not just a plug-in or as easy as with the later bikes.

K-Bike,

Thanks for the advice, No I dont have the installation manual, as you mentioned very simple devices and i thought it would be as simple as just mounting and hooking up the appropriate colour match wiring.

Does anyone have an installation manual for accessory gauges?

Col

K-Bike,

As far as checking with an ohm metre are you able to suggest any way of testing the guages so I can rule out a problem with them.

Col

A Gauge is no more than a volt meter.
take the temperature gauge as an example:
Positive 12 volt is constant and negative is regulated by the temperature sensor.
To install a gauge on your bike, you need the extra temperature sensor. The original one (2 sensors build into one unit) is (are) feeding the EFI computer and the temperature switching unit (The one that will turn your fan and red light on). If you try to install an extra device on one of the switch, the original device attached to it may receive a false information.

Bert

Bert thanks for that info I havent connected the temp sensor as yet (yet to purchase) am told that the colant drain plug can be replaced with additional Temp sensor.

In theory then I should be able to bench test the guages by hooking up positive supply, and earth and then if I was to earth the sensor wire I should get a 100% reading on the guage either temp or fuel being fully hot or full on the fuel.

Is that correct?

Hi Col,
If you send me a PM with your email address I will send you the installation sheet for the temperature gauge.
Regards,
K-BIKE

Yes this is right!
Here is a chart of the resistance values of the original temperature sensor.
If you want to bench test test your gauge, select a temperature on this chart, and insert a resistance of the equivalent value on your test bench.

Thanks for this information combined with the correct installation manual i should be able to get these things working.

havent been around for a bit and just catching up on here
I added gauges I bought from Ebay plus a temp sender I bought from
a BMW dealer to my 87 K100RS which has a fairing and bars from an 85 RT
I made up my own wiring harness and they work well and are accurate too.
If your still struggling let me know and I'll have a look for the the info
I have plus the pics I took

Hi All,

Managed to get everything working properly rechecked everything bench tested the gauges as described above, refitted and this time hooked up the fuel tank wiring prior to testing on the bike and presto the fuel gauge worked and the smoke stayed inside the wiring this time. (no smoke) then fitted the sender unit for the tem and that worked as well.

Thanks all for your help especially Crazy frog and K-Bike.

I look forward to to future discussion as I continue to explore the world of bmw bikes.

Bones

Bones,

It would be good if you could post a small electrical schematic of your extra wiring. (Where you picked up the power and if any modifications had to be done on the harnais).
Since you had previous Indian signals from your gauges (puffs of smoke), you could put an extra fuse inline with the power. (one like this would be perfect)



Bert

Hi Bones,
Glad to hear you have got it working with no escape of the high pressure smoke! To think some fools believe it is electrons that do the work good job we know better.
Regards,
K-BIKE

Here is what I just found on another forum:

Hi All,

I will draw up a diagram and post it so that other users dont fall victim to the indian signals.

Bones

Here is the BMW info with the wiring at the end. It's in German, but the schematic should be easy and 'babelfish' is your friend.

http://www.ziegeltreiber.de/images/c/cb/Zusatzinstrumente.pdf