Author Topic: Temperature light flickering (Read 59163 times)

SeanK75 · « **on:** February 21, 2015, 10:12:40 AM »

Hey guys,

I think I have a wiring issue but here is what's happening

-Fan and fuel pump come on at when the ignition is on.

-Fan is always on.

-Horn fuse blows occasionally.

-Temperature light flickers once in a while.

I've checked all the relays but I'm guessing I have a short somewhere? I can't imagine my temp is high as my coolant is topped up and and my fan runs all the time. Has any body else had the symptoms? Any advice?

Any help would be greatly appreciated. It's a 1994 K75s with 95000km.

Thanks!

johnny · « **Reply #1 on:** February 21, 2015, 11:35:29 AM »

greetings seank75...

welcome to motobrick.com...

the fuel pump should not run unless you are first on the start button...

first thing i would do is remove the horn from the circuit and see if the fan still runs from cold... cause... shorted horns have been known to cause fan whack... usually no fan cause they are on the same fuse...

proally stuck relay though... butts i would look at the fuse block first... some folks put a wire jumper in there to power the fan circuit for constant fan to help reduce thigh roast...

the wiring for that motobrick is here...

j o

SeanK75 · « **Reply #2 on:** February 21, 2015, 12:01:36 PM »

Hey Johnny,

Thanks for the help. By remove the fan from the circuit, do you mean disconnect the wire connection on the horn or from the relay? Horn is obviously more accessible. I had it in the shop in the summer and we swapped all the relays out with another k75 and same problem so I think the relays are ok.

Thanks

mw074 · « **Reply #3 on:** February 21, 2015, 12:05:15 PM »

Check temp sender to see if has gone to ground.

johnny · « **Reply #4 on:** February 21, 2015, 12:08:23 PM »

horn...

id also remove and reset each fuse on ata time... look for a jumper installed with unskilled hands...

j o

SeanK75 · « **Reply #5 on:** February 21, 2015, 01:59:46 PM »

Thanks for the advice guys. I'm on a trip right now so I'm limited to the tools I have on me. I tried disconnecting the horn and didn't help. Anything else I can check without major surgery? Is the temp sender easily accessible?

Thanks

johnny · « **Reply #6 on:** February 21, 2015, 02:46:39 PM »

greetings...

somebody here knows for sure butts it aints me... so in the meantime i would disconnect the connector from the jetronic brain... make sure its all clean... reconnect and see what happens... lotts of whack can happen because of those connections...

what is your whereabouts right now...

j o

Inge K. · « **Reply #7 on:** February 21, 2015, 08:50:17 PM »

About your fan and warning light, this can happen if the relay have insufficient ground connection.
Try to run a temporary wire between the relay ground connector and battery negative terminal.

About the blowing fuse it's most likely that you have a short in the wires to the horn(s) or the fan.
Unless it have been a lot of modification in your relay box....the fuse supplies horn, fan and flasher relay.

Scott_ · « **Reply #8 on:** February 21, 2015, 09:27:04 PM »

Expanding on what Inge suggested, there is also the remote possibility that the short/fault that's blowing your fuse could be the fan motor itself. they can/do go bad. More often than not they seize up and stop turning, but I have seen some that the brush holders inside the motor melt/deform and are then capable of shorting out.

SeanK75 · « **Reply #9 on:** February 21, 2015, 10:06:49 PM »

Thanks for all the suggestions guys. The fan is running all the time. As soon as I turn the key, even before it starts. My bike broke down and now it won't start. Finding this wiring issue seems like finding a needle in a haystack, but I'm going to pull the tank off tomorrow and get out my multimeter. My clutch boot and fuel filter went on my last trip, I'm beginning to wonder if touring with a 20 year old bike is a good idea, even if it is a kbike! I've done some reading and it sounds like it could be the temperature sensor so I'm going to check that first and inspect and flush the cooling system while im at it. I'll let you know what I find.

Thanks again for responding, it's really nice have some help in these situations.

Inge K. · « **Reply #10 on:** February 22, 2015, 03:50:18 AM »

The sensor is of a dual element type, one for fan relay...the other for the Jetronic to calculate the mix.
As a test you can check both values and compare them, they should be identical.

Measure the resistance between contact #10 and 13 at the injection ECU Connector.
Count from the rear end, also the empty slots.
Remove the relay and measure between 31 and E in the socket.
At 25^oC you should measure around 2300 ohms.

Higher temp.....lower resistance, if the wires or the element is shorted to ground...the Jetronic thinks
the engine overheats and it's not allowed to start.

SeanK75 · « **Reply #11 on:** February 22, 2015, 02:27:46 PM »

So I removed the harness from the temperature sensor and the fan is still coming on regardless Does that mean I've eliminated the possibility of the temp sensor?

Scott_ · « **Reply #12 on:** February 22, 2015, 03:45:00 PM »

Quote from: SeanK75 on February 22, 2015, 02:27:46 PM

So I removed the harness from the temperature sensor and the fan is still coming on regardless Does that mean I've eliminated the possibility of the temp sensor?

Most likely not the sensor then if the fan still comes on. The jetronic computer provides the 'ground' reference for the fan relay, so there has to be something telling the computer to turn on the fan, or more than likely, you have some funky (ie dirty) ground connections. Sounds like the next step may be to open, and clean any/all ground connections from the battery to the multiple frame connections. And as Johnny suggested clean the computer plug contacts- both sides.

On the odd chance, did a previous owner install a manual fan override switch?

While you had it unplugged, did you try and start it?

SeanK75 · « **Reply #13 on:** February 22, 2015, 04:07:44 PM »

So I pulled the computer out and inspected the pins and it looks fairly clean. I tried to measure resistance from pin 10 to 13 and no reading came up. I tried to measure resistance from 31 to E on the fan relay socket, NOT the relay itself and no reading came up. Electronics is Greek to me. I can do a spline lube and replace the clutch but I'm limited with electrical knowledge. If I'm testing the resistance of the sensor do I touch each of the terminals on the sensor itself with the red and black leads of the multimeter?

Thanks guys

Inge K. · « **Reply #14 on:** February 22, 2015, 04:12:36 PM »

When you did test for resistance, was the sensor connector connected?

SeanK75 · « **Reply #15 on:** February 22, 2015, 04:13:42 PM »

Ok tell me if this means anything. I tested the continuity from the fan relay ground (31) and the fan harness and it beeps. When I try the temp sensor harness I get no beep. Could that mean there's a ground fault between the relay and the temp sensor?

Thoughts?

SeanK75 · « **Reply #16 on:** February 22, 2015, 04:17:46 PM »

Ok I plugged in the temp sensor and tried again. I got 3.72 between #10 and 13 on the cpu harness. And 0.7 between 31 and e on the relay.

Inge K. · « **Reply #17 on:** February 22, 2015, 04:25:30 PM »

Then it's the sensor that is the problem as the measured value for the relay is to low.
But it could also be the contacts or wiring, try to measure between each of the contacts on the sensor
and ground (sensor housing is ground)....if you gets the same values you need a new sensor.

SeanK75 · « **Reply #18 on:** February 22, 2015, 04:34:54 PM »

Housing meaning the connector pipe that the sensor threads into? I get readings that jump around between 8.00 and 12.00 on both contacts.

SeanK75 · « **Reply #19 on:** February 22, 2015, 04:38:07 PM »

I tried putting the black lead directly to 31(ground) on the relay and the red to each of the temp sensor connectors and it gave me the same consistent reading of 3.6.

Inge K. · « **Reply #20 on:** February 22, 2015, 04:43:51 PM »

Then it seems like the sensor is OK, and the problem is somewhere between the sensor and the relay socket.
I'm assuming that the engine is stone cold.

First check the that the sensor connector is clean and no corrosion, next to check is the connector between
the engine harness and the chassis harness (five pole, under the tank, left rear corner) and of course the
relay socket (but that usually isn't a problem).

SeanK75 · « **Reply #21 on:** February 22, 2015, 04:46:24 PM »

Yes its about 7 degrees celcius here, just over 40 degrees Fahrenheit. I'm getting a steady 3.6 now on both connectors when I ground it the the connector pipe that the sensor threads into. Engine won't start and gas tank is off.

SeanK75 · « **Reply #22 on:** February 22, 2015, 05:05:02 PM »

So its likely a ground fault between the sensor and the relay correct? If things were functioning normally I would get a consistent 3.6 reading between 31(ground) and E(temp sensor)?

What the best way to chase this down. Check all grounds and failing that unwrap and chase the wires from the sensor to the relay?

Inge K. · « **Reply #23 on:** February 22, 2015, 05:11:24 PM »

The ground is OK, the connection between the sensor and the relay socket is the problem.

Check the connectors as earlier described (post 20), you can also try to measure at the
chassis/engine connector to if it is any difference from the 0.7/3.6.

SeanK75 · « **Reply #24 on:** February 22, 2015, 05:24:12 PM »

Is this the right one? Which socket do I test? And to the relay or sensor?

Thanks

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Author Topic: Temperature light flickering (Read 59163 times)