BMW K bikes (Bricks)

You are not connected. Please login or register

Go to page : Previous  1, 2

View previous topic View next topic Go down  Message [Page 2 of 2]


costellon


active member
active member
@Laitch wrote:
@costellon wrote:Update: Replaced temp switching relay with a known working unit and same result - no fan or light when E pin is grounded. Anyone care to comment or offer any advice ?
Thanks
What is the problem you're trying to diagnose, or the goal of your testing?
Thank you for your reply Laitch.

I will begin again. During normal operation I have no cooling fan or temperature light. Grounding the wire at the coolant sensor should cause the fan to rotate and light to illuminate - but it doesnt. This wire comes from pin E on the temperature sensing relay.

As I have explained in my previous posts - the fan spins when I put positive power to pin A2 on the temperature sensing relay - so THATS getting power and functioning, also the temperature light illuminates when I ground pin A3 to earth, so THATS also working ..... but - and this is the important "but" - when I ground pin E of the temperature sensing relay I get nothing - when I should have the fan spinning and the temperature light illuminated.

According to the title of this thread - that should be indicitive of a bad temp sensing relay - but I have swapped the relay out with 2 unknown and 1 fully functioning relay - and still I neither have a fan spinning or light lit when I ground pin E ....... THAT IS - My cooling fan and temperature light do not function when the engine goes above normal operating temperature and my bike will boil over if I allow it to run when stationary - why is this happening and how do I fix it ?

If when grounding pin E and nothing happens re fan and/ or light is indicitive of a bad relay - and I have changed said relay with a fully functioning unit why are my light and fan still inoperable on grounding pin E ???? The problem is quite obviously not the relay but something else ..... but what ???? 

Pin E on the temp sensing relay is dead as a dodo - why ?

Thankings

    

92KK 84WW Olaf

avatar
Life time member
Life time member
Did you use PTFE tape by any chance?


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 39.885miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

Point-Seven-five

Point-Seven-five
Life time member
Life time member
Is it safe to assume you have 12v on pin 9 of the temperature relay?

When you ground the pin E are you doing it at the terminal on the relay socket or at the actual terminal on the relay? I wonder if you might have a problem in the relay socket. That would explain all the other relays not working.

Is there 12v at pin 15 of the temperature relay?

Does putting 12v at pin A2 of the temperature relay socket turn on the fan?


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

costellon

costellon
active member
active member
@92KK 84WW Olaf wrote:Did you use PTFE tape by any chance?
Thanks for the reply, I get where you are coming from but as I am testing at pin E on the relay  - I am by-passing the coolant sensor and should be getting a result. Essentially, pin E is the wire to the sensor - and i'm grounding it to earth

    

costellon

costellon
active member
active member
@Point-Seven-five wrote:Is it safe to assume you have 12v on pin 9 of the temperature relay?  

When you ground the pin E are you doing it at the terminal on the relay socket or at the actual terminal on the relay?  I wonder if you might have a problem in the relay socket.  That would explain all the other relays not working.

Is there 12v at pin 15 of the temperature relay?  

Does putting 12v at pin A2 of the temperature relay socket turn on the fan?
Thanks for the reply

Tests so far:
+ to A2 turns the fan on (ignition on or off) - so yes to "Does putting 12v at pin A2 of the temperature relay socket turn on the fan?"
15 to A2 turns the fan on (ignition on or off) - so I presume that there is 12v @ pin 15 ("Is there 12v at pin 15 of the temperature relay?")
- to A3 illuminates the red temperature dash light (ignition on only)
- to E does nothing

"When you ground the pin E are you doing it at the terminal on the relay socket or at the actual terminal on the relay?  I wonder if you might have a problem in the relay socket.  That would explain all the other relays not working." - I have been testing at both

I'll check pin 9 tomorrow evening, thanks again

    

56Back to top Go down   Testing Temperature Switching Relay - Page 2 Empty Re: Testing Temperature Switching Relay Mon Dec 07, 2020 12:54 pm

costellon

costellon
active member
active member
@Point-Seven-five wrote:Is it safe to assume you have 12v on pin 9 of the temperature relay?  

When you ground the pin E are you doing it at the terminal on the relay socket or at the actual terminal on the relay?  I wonder if you might have a problem in the relay socket.  That would explain all the other relays not working.

Is there 12v at pin 15 of the temperature relay?  

Does putting 12v at pin A2 of the temperature relay socket turn on the fan?
Apologies, work has been hectic. I finally found the time to dig the K out of the back of the workshop and test pin 9 on the temp relay - i'm getting MINUS .15 volts - ignition on or off, also, there's no voltage at the 2nd last fuse from the bottom, I have 12v at pin 30 of the FI relay ...
Thanks

    

57Back to top Go down   Testing Temperature Switching Relay - Page 2 Empty Stupid question Tue Dec 08, 2020 6:29 pm

costellon

costellon
active member
active member
This is a stupid question perhaps - but should I be conducting these tests with the engine running ?

I seem to remember something from years ago with another K that I had whereby fuse 6 had no power until the starter button is pressed and the engine started ..... is this the case ?

Thanks

    

58Back to top Go down   Testing Temperature Switching Relay - Page 2 Empty Re: Testing Temperature Switching Relay Tue Dec 08, 2020 11:05 pm

robmack

robmack
Life time member
Life time member
You're right. Engine must be running so power is at fuse 6.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

59Back to top Go down   Testing Temperature Switching Relay - Page 2 Empty Temperature sensing unit Tue Dec 08, 2020 11:54 pm

daveyson

daveyson
Life time member
Life time member
I've read that if the computer senses that the engine is overheated it will deny the start button request. That might explain the baffling test results at pin E. So I'm with Olaf to check for a good connection at the temperature sensor, and the sensor itself.

You might have a power fail at pin 9, or an earth fail at 31. With a fused jumper wire between 31 and A3, the temperature light should glow. If so your earth is good.

Although some drawings show the fuses supplied from the left, I believe they are supplied from the right, that might explain why you read -0.15V.

On my brick with the ignition on, fuel pump unplugged, temperature sensing unit unplugged, fuse 6 removed, fuel injection relay unplugged, and a fused jumper wire between 30 and 87b (as in the photo) of the fuel injection relay, I'm reading 0.19V on my multimeter with the red probe on the right socket where fuse 6 was, and the black probe on the left. Reversing the probes gave me -0.18V. So I think your reading of -0.15 is OK, I'm assuming your tank and sensing unit were unplugged, plus the other mentioned assumptions.

If you read 12V after this test, you have a short in the wiring.

Important, remove the fuse first, and remove the jumper wire as soon as the test is finished.

Testing Temperature Switching Relay - Page 2 Img_2016



Last edited by daveyson on Wed Dec 09, 2020 4:47 am; edited 7 times in total (Reason for editing : Add photo)


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

60Back to top Go down   Testing Temperature Switching Relay - Page 2 Empty Temperature sensing unit Wed Dec 09, 2020 7:46 pm

daveyson

daveyson
Life time member
Life time member
A few things I forgot to mention.

My test results were the same as yours, so grounding E didn't cause the fan or light to come on, so I think that's normal.

Repeating the earlier test with fuse 6 replaced, bridging 9 and A2 should also turn the fan on, confirming power to 9 is good, as Point-Seven-Five earlier asked.

If these input test results are good, I think they will be, I'm guessing it's the temperature sensor that's the problem.

One test result was different though. You say bridging 15 to A2 turns the fan on, with ignition on or off. That didn't work for me with the ignition off. That makes me think your load shed relay is stuck on, if so the headlight won't cut out while cranking. Probably Not your main problem, but something to look at while you're there.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

61Back to top Go down   Testing Temperature Switching Relay - Page 2 Empty Time Tue Dec 15, 2020 4:22 pm

costellon

costellon
active member
active member
Finally got the time to put the tank back on, fuel it up and START THE ENGINE.
Low and behold - when I ground pin E on the temperature sensor relay - both the temperature warning light and the fan come on.

So, to put it another way, if the bike isnt running - grounding pin E wont do anything. Either the starter button has to be pressed or the engine has to be running in order to energize fuse 6 - which then feeds the fuel injection relay which then feeds pin E on the temperature sensing relay.

To anyone conducting the test on pin E that the Author described - do so with the engine running.


Sincere thanks to all for your contributions, advice and time

Be well

    

62Back to top Go down   Testing Temperature Switching Relay - Page 2 Empty Temperature sensing unit Tue Dec 15, 2020 4:42 pm

daveyson

daveyson
Life time member
Life time member
OK, so grounding pin E with the engine running turned the fan on,  but will the temperature sensor turn the fan on with the engine running  when it gets too hot,  have you verified that yet?

"Why is this happening and how do I fix it"

I think all your symptoms are consistent with a faulty temperature sensor signal. I'd test the temperature sensor.

For starters at the female plug (loom side) of the fuel injection computer, with the engine cold (say 20 Celsius)  you should read about 2.5 kOhms, between pin 10 and earth (pin 13 is also earth) At normal operating temperature about 300 ohms.Testing Temperature Switching Relay - Page 2 Img_2018


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

costellon

costellon
active member
active member
@daveyson wrote:OK, so grounding pin E with the engine running turned the fan on,  but will the temperature sensor turn the fan on with the engine running  when it gets too hot,  have you verified that yet?

"Why is this happening and how do I fix it"

I think all your symptoms are consistent with a faulty temperature sensor signal. I'd test the temperature sensor.

For starters at the female plug (loom side) of the fuel injection computer, with the engine cold (say 20 Celsius)  you should read about 2.5 kOhms, between pin 10 and earth (pin 13 is also earth) At normal operating temperature about 300 ohms.Testing Temperature Switching Relay - Page 2 Img_2018

Thanks Daveyson for another helpful and informative post. I actually changed the temperature sensor in mid November with a known working unit off one of my other K's. The old one tested faulty AND was installed with ptfe tape.

I have not had time to take it up to operating temperature and test the circuit in the real world yet but will do so when the presssure at work eases off - at least now the mystery of "pin E" has been resolved.

Every evening after work I only have 2 hours in which to cook, eat, update my correspondence and tend to my chores before sleep.
I'll get back to the bike next week hopefully.

Thanks again, be well

    

64Back to top Go down   Testing Temperature Switching Relay - Page 2 Empty Temperature relay Tue Dec 15, 2020 7:56 pm

daveyson

daveyson
Life time member
Life time member
OK, got it. As a side issue, next time you crank it, might be worth looking to see that headlight cuts out.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

View previous topic View next topic Back to top  Message [Page 2 of 2]

Go to page : Previous  1, 2

Permissions in this forum:
You cannot reply to topics in this forum