Cooling Fan Test

[cool]

Fellow Brick Riders,

I understand the Clymer's manual says the operation of the cooling fan can be tested by jumpering the terminals at the temperature sensor cable. Doing so is supposed to cause the cooling fan to run. Has anyone successfully tested the fan using this method?

Thanks!

D Cool
88 K75C

[johnny]

not me... butts I have jumpered power to the under tank connector to power the fan...

j o

[Inge K.]

Jumping the connectors won't help you....the sensor is a dual element, which both elements
measure the resistance to ground.
One element is for the fan, the other is for the injection ECU (for calc the mix)
Disconnect the multiconnector at the injection ECU....and try to ground each of the
connectors at the sensor to start the fan (both have the same colour code).

[cool]

Johnny,

If you mean the relay terminals for the fan, I did that too and the fan runs.

D Cool
88 K75C

[johnny]

yawl... on one of my motobricks I hot wired the 2 pin under tank fan connector and switched it on and off with a red toggle switch...

welcome to motobrick.com there cool... listen to inge k... he knows more about motobricks than me... im just a trail braking throttle whacker...
j o

[cool]

Inge K.

"Jumping the connectors won't help you"

I got that information from the ibmwr.org K tech pages. 

So when I jumpered (is that a word) the cable connections and the fan didn't run.

So I looked again at the wiring diagram.
 
The lines to the temperature sensor are grounded to the engine block through the sensor.

The wiring diagram shows a violet/green wire runs directly to fuel injector control plug terminal 10, the other violet/green wire runs to terminal E at the relay/switch.

I re-read your post. I will remove the fuel injection control plug and ground each sensor plug terminal to see whether the fan will run.

Thanks!   

D Cool
88 K75C

[Inge K.]

The IBMWR sensor test would function on a sensor which have the resistance element
between the terminals, and not connected to ground.
This kind of sensor is more common...and is used on the 4V bricks which got a different
engine management system.

[rbm]

If you are planning on installing a switch to manually override the temperature sensor, then you want to ground the violet/green wire leading pin E on the fan relay with the switch you plan to install.

If you want to test the operation of the fan as part of a diagnosis, then remove the fan relay from its socket and jumper pins E and 15.

[Inge K.]

If you want to test the operation of the fan as part of a diagnosis, then remove the fan relay from its socket and jumper pins E and 15.

Not quite correct, Robert.
If you jump pin E and 15, all you would achieve is to feed the sensor with 12V+.
If you want to test the fan circuit w/o the relay you must jump pin 15 and A2.

By grounding the wire to the sensor (E),  relay function is also being tested.

Inge K.

(Corrected by Inge K. after advice from RBM).

[cool]

Inge K. and all,

I removed the multi pin connector at the fuel injection control. I removed the temperature sensor plug and grounded each terminal to the block. The fan did not run. Since the coolant fan relay/switch is new, I believe the connection to terminal E is likely damaged.

Thanks!

D Cool
88 K75C
 

[Scott_]

I would think that the early K1002V would be real similar to the K75, no?

From Here. Bert Vogel

Pictures are good...

[wmax351]

More than just similar: identical.

[Inge K.]

Inge K. and all,

I removed the multi pin connector at the fuel injection control. I removed the temperature sensor plug and grounded each terminal to the block. The fan did not run. Since the coolant fan relay/switch is new, I believe the connection to terminal E is likely damaged.

Thanks!

D Cool
88 K75C

Start to remember a similar issue in another forum a couple of years back....a bit late...
It is a bit more complicated than just to ground the sensor, you also need power to pin 9
from the FI relay.....to close the FI relay contacts the engine must be turning.
You could try to turn the starter for a few seconds.

The starter signal is enough to make the FI relay close it's contacts for 1,5 -2 seconds
w/o the engine turning.....but don't know if that's enough to start the fan.

Inge K.

[Scott_]

Inge K. and all,

I removed the multi pin connector at the fuel injection control. I removed the temperature sensor plug and grounded each terminal to the block. The fan did not run. Since the coolant fan relay/switch is new, I believe the connection to terminal E is likely damaged.

Thanks!

D Cool
88 K75C

Start to remember a similar issue in another forum a couple of years back....a bit late...
It is a bit more complicated than just to ground the sensor, you also need power to pin 9
from the FI relay.....to close the FI relay contacts the engine must be turning.
You could try to turn the starter for a few seconds.

The starter signal is enough to make the FI relay close it's contacts for 1,5 -2 seconds
w/o the engine turning.....but don't know if that's enough to start the fan.

Inge K.

Wouldn't the "starter signal" drop out the load shed relay? purpose to not let the fan run when trying to start.

[Inge K.]

Wouldn't the "starter signal" drop out the load shed relay? purpose to not let the fan run when trying to start.

You're absolutely correct, Scott......this test wasn't that easy.
....Terminal E must be shorted to ground....and engine be running.