Warning lights install on K bikes

[sooprvylyn]

Hi all,

This post is meant to help people who want to connect aftermarket warning lights to their k bikes correctly. I finally got mine all set up and working, so I wanted to let people know what I did. I am only covering the 3 necessary warning lights, no fuel light, no neutral light, no blinker light.

Oil pressure light-(same setup on all K bikes)
The oil pressure sensor is located at the oil/water pump. It is the sensor on the back side of the pump. The front side is a coolant temp sensor, which ill mention in the engine temp light section. There are 2 wires connected to these that go up from the pump and through the hall effects sensor cover on the front of the timing chain cover before exiting under the radiator. The oil pressure sensor terminates in a white connector. Connect this wire to the oil pressure warning light's NEGATIVE terminal. Connect the positive terminal on your warning light to power(aux output on m.units, or somewhere on your bike that gets power when the bike is turned on).
 
***This light will illuminate when you turn the bike on and until the oil pressure builds after starting the engine, then it will turn off. It will illuminate if you lose oil pressure

Engine temperature light(16v and 8v K bikes will have a slightly different connection, read comment below mine)
The 2nd wire that comes from the oil/water pump, the one with the blue connector? Delete it unless you plan to connect it to an engine temperature guage. It's irrelevant to the warning light. There is a 2nd water temp sensor located on the metal pipe behind the radiator, on the left side. This sensor feeds into your ECU. The ECU will act as the trigger for your engine temp light. For 16v bikes your original cluster there is a brown/black wire, on 8v K bikes it is purple/black and it comes from your temperature sensing relay. Connect this wire to the NEGATIVE terminal on your engine temp warning light.  Connect the positive terminal on your warning light to power(aux output on m.units, or somewhere on your bike that gets power when the bike is turned on).

***This light WILL NOT illuminate when the bike is turned on. It will only illuminate if your engine temperature gets too hot.

Battery warning light(all K bikes)
On your alternator you will see a big terminal and a small terminal. The big terminal connects to the pos on your battery. The small terminal is the alternator exciter circuit negative. Connect this to the NEGATIVE terminal on your battery warning light. Connect the positive terminal on your warning light to power(aux output on m.units, or somewhere on your bike that gets power when the bike is turned on).
If you are using an LED battery warning light
Your original exciter circuit used a 3w warning bulb as a load on the circuit. This has a 48ohm resistance. Your led bulb has significantly less resistance and it is not enough to activate the exciter on the alternator. You need to add in a 50ohm resistor IN PARALLEL with your warning light in order to get enough resistance.

***This light will illuminate when you turn the bike on and until the alternator is putting out power after starting the engine, then it will turn off, and there will be no significant current running through the circuit. It will illuminate if your alternator stops juicing your battery.


Perhaps someone will pop in with wiring details for a fuel light.  I don't run one, I just top off before each ride and again after about 2 hours of riding and this has been fine for me.

[frankenduck]

The engine temp sensor on 2V K bikes is a DUAL sensor. One lead goes to the L-Jetronic (ECU) for controlling the fueling. The other lead goes to the white thermo relay that controls the fan and temp warning light.

You don't need a resistor in the alternator lamp circuit to use an LED but you do need to rev the bike up to 2,000 RPM or so until the alternator starts working and the light goes out. You are running off of battery power until that light goes out.

Example:

[sooprvylyn]

Thanks for the clarification on the 8v coolant sensor setup.

The 2k rpm thing explains why I never ran out of battery on my k75 that had no light, and on my k1100 that ran w/o an alternator exciter circuit for the past 10 month or so. The more you know.

The resistor duplicates the stock setup, but seems reving to 2k rpm will get the alternator going without the resistor.

[frankenduck]

Fuel light: The fuel level sender (FLS) grounds the white wire. There is delay circuitry built into the factory instrument cluster so that the low fuel light does not flash on and off as fuel sloshes around in the tank and the ping pong ball float goes up and down.

You could wire up an LED to the white wire but without the delay circuitry it would probably flash a lot as fuel sloshes around and be very annoying but when the bike is stationary it would tell you if you're low on fuel.

[sooprvylyn]

The engine temp sensor on 2V K bikes is a DUAL sensor. One lead goes to the L-Jetronic (ECU) for controlling the fueling. The other lead goes to the white thermo relay that controls the fan and temp warning light.

Are we  just talking about the single sensor behind the radiator? The one with a 2 pin connector? The body of the sensor screwed into the frame is ground right?

Im pretty sure that blue connector coming from the pump housing is still just for the the temp guage connector.  LMK if Im missing something.


If yes, this is pretty similar to the k1100

[frankenduck]

Are we  just talking about the single sensor behind the radiator? The one with a 2 pin connector? The body of the sensor screwed into the frame is ground right?

Im pretty sure that blue connector coming from the pump housing is still just for the the temp guage connector.  LMK if Im missing something.


If yes, this is pretty similar to the k1100

You are essentially correct. The temp sensor screws into the metal coolant exit tube (not the frame) which grounds it.

Yes. The water pump temp sensor only feeds the gauge.

[sooprvylyn]

Awesome, thanks