Technical Radiator fan not kicking in

[NiekUntamed]

I was unable to get a test light. Once I do, what is the next step?

 

[koalar]

I would manually trigger the control side of the coil and see if the fans operate


Let me find the correct diagrams


There's quite a few, 4x4, dualogic, LPG, with A/C and so on

 

[NiekUntamed]

I would manually trigger the control side of the coil and see if the fans operate


Let me find the correct diagrams


There's quite a few, 4x4, dualogic, LPG, with A/C and so on

I already did that. It only triggers if I give the control wire negative from under the fusebox or if I bridge the contacts with the relay unplugged, but it does trigger.

 

[NiekUntamed]

From following the wires I see that the relay gets a positive on the trigger leg from a common positive in the fusebox. The one coil switch side gets a positive through the fuse and the other side of the coil goes to the resistor. The trigger wire is from the ecu. I know it is a brown wire but I am not sure of the pin. It is at the end that neighbours the smaller plug and is second from the left if I remember correctly.

 

[NiekUntamed]

I think this diagram should be the one. Maybe you can confirm.

 

[koalar]

Pin 8 on connector B of the ECU


But when we shorted the temperature sensor out the ECU should have used pin 18 for fans speed two


Relay T07

 

[NiekUntamed]

Pin 8 on connector B of the ECU


But when we shorted the temperature sensor out the ECU should have used pin 18 for fans speed two


Relay T07

I Agree that it should have triggered, but nothing. Even doing that while bridging the resistor still triggers nothing. The aircon relay did feel quite warm to touch and triggers the monent you plug it in. Can this be related?

 

[koalar]

The engine check light coming on is great, the ECU has detected a problem and put the fans on speed 2

Unfortunately we have only tested speed 1

The green high lighter is what we know is working

This is only speed 1

Tricking the sensor will only use speed 2

It uses a different control line were X is

With the relay T07 unplugged do we have battery voltage on two of the pins

 

[NiekUntamed]

The engine check light coming on is great, the ECU has detected a problem and put the fans on speed 2

Unfortunately we have only tested speed 1

The green high lighter is what we know is working

This is only speed 1

Tricking the sensor will only use speed 2

It uses a different control line were X is

With the relay T07 unplugged do we have battery voltage on two of the pins

View attachment 465883

Thank you for yet another well written response. Yes. When unplugging each relay I get 12v on the one side of the coil and the one side of the trigger on both relays.

 

[NiekUntamed]

Thank you for yet another well written response. Yes. When unplugging each relay I get 12v on the one side of the coil and the one side of the trigger on both relays.

I tested speed 2 as well. All wires check out. Fan switches on at high speed when bridged or when given negative at the trigger wire. Trigger wire stays positive even at high temperature. I don't know about you, but I think this is starting to look like an ECU issue. Please let me know if there is anything else I can test for before having the ECU checked.

 

[koalar]

Well done in checking it yourself, I was going to say test speed 2 exactly the same as speed 1 last night but forgot to hit the post reply button

Yes we are running out of options

Everything in green has been tested as working
E50 is the dash
K36 is the coolant sensor
M1 is the body computer

The problem is to the right of the diagram

You can eliminate K120 by unplugging it

I have seen wiring damage here cause the fans fans to be on permently but not the other way round

Then we are down to testing the continuity between the fuse box and the ECU

And inspecting the pins on the ECU and connector

 

[NiekUntamed]

Thanks for your response and illustrations. I already checked continuity on all wires to do with the radiator fan. I found the temp sensor wires cut and very poorly joined, so crimped and insulated it properly. I will unplug the K120 tomorrow and give you feedback of what I find.

Any idea what to look for after unplugging K120? Should I also bridge the connector?

I will keep you posted on my findings. Thanks for your input. Guys like you keep forums like these alive.

 

[koalar]

Just unplugged, should be the same as no gas in the system

 

[NiekUntamed]

Just unplugged, should be the same as no gas in the system

I unplugged it and nothing changed.

 

[koalar]

I unplugged it and nothing changed.

Shame, it was a long shot

That everything eliminated except for the ECU

You can double check it by removing relay T07

Putting your multimeter on pin 51 (relay control)and battery positive, engine running

Should read battery voltage when the coolant sensor is shorted

Or if the fan is activated via bidirectional software, MultiECUscan, Delphi,wow or similar

If you post a decent photo of the connector and ECU pins something might show up, still a long shot as both speed 1 and 2 aren't working

 

[NiekUntamed]

Shame, it was a long shot

View attachment 465961

That everything eliminated except for the ECU

You can double check it by removing relay T07

Putting your multimeter on pin 51 (relay control)and battery positive, engine running

Should read battery voltage when the coolant sensor is shorted

Or if the fan is activated via bidirectional software, MultiECUscan, Delphi,wow or similar

If you post a decent photo of the connector and ECU pins something might show up, still a long shot as both speed 1 and 2 aren't working

I have tried actuating the fans. It allows the action in Delphi, but nothing happens besides bringing up DTC codes for Fan speed 1 and 2. The relay trigger wires stay at postive 12v with temp cold or warm.