Cooling fans constantly running

I think this has been covered, however I need assurance.

series of events.
LR1 perfect for a couple of weeks.

Over night battery dead.

Ordered new battery.

Replaced.

Cooling fans start running at full speed.

Cooling fans "stop" as soon as ignition is turned on.

Replaced temp sensor, replaced every relay and fuse.
---------

1.Fuse 4 in engine bay removed and cooling fans stop.

2.Cooling connector plug (C1680) removed will also stops the fans

So my question is, after all the checks, is it highly probable the ecu has an issue and needs to be replaced or have i missed something?

You need to check the cooling system ECU is getting the correct signal.
This is applied on the thin Blue/White wire. This signal is in the form of a variable duty cycle pulsed feed.
0 to 9% wouldn't run the fans. 10 to 90% slowly increases fan speed. 90% and over gives maximum speed.
You can test this feed with an meter but a scope is better.

Thanks for the answer.

I know from basic tests (with a crocodile clip a piece of wire and a handy bulb) that it would appear, that both the blue and white cable and the brown are producing negative.

Being new and know little of electronics.

If the ecu is receiving the incorrect signal, how should I correct it.

I am at a complete loss as to why or how this has happened and can only assume the ecu has a fault.

Wondering if a basic reset of the ecu may clear this.

Open to any suggestions.

Here's the description of the system from the manual. My figures were a bit off, but I was going on my clouded memory!
If the fan ECU receives an unusual or out of spec signal on the control wire. It puts the fans on max speed to protect the engine.

Yep.
I've search all the manuals and electrical wiring diagrams.
That's what I came up with too.

It does indeed point directly to an ecu issue/fault.

I have a spare ecu from a donor Freelander, just need to work out how to get it working on mine.
I believe it needs reprogramming some how.

Really appreciate your time and help by the way.

Reset the ecu... though I doubt the standard method (red lead on the positive, wait 10 mins) actually did diddly.


However the plot thickens.

The issue seems to stem from something electrical within the engine bay.

When the ignition is turned off, there is something making a high pitched sound.
I can't make out where exactly but somewhere near the rear of the engine bay.
After around 3-4 mins it stops, that's when both fans start up and quickly progress to full speed, until I pull fuse 4 out.

What is causing that high pitched noise?

Many thanks in advance.

What engine is it ?

Nodge68 said:

What engine is it ?

Click to expand...

1.8 (2003)

ALR2 said:

1.8 (2003)

Click to expand...

Next test is to check the integrity of the wiring between the engine ECU and fan controller.

That's a lot easier said than done.
But that'll be my next course I think.

I've also heard that maybe the thermostat may have failed.

But as you said, everything points to an ecu-fan controller.

I'll have a look tomorrow.

Continuity is good.
However. When the connecting the ecu connector back on continuity is lost.

If I had hair I would of pulled it all out by now.

Nodge68 said:

Next test is to check the integrity of the wiring between the engine ECU and fan controller.

Click to expand...

Brown is 5v - engine turned off
Blue is 0v

Brown is 12v - engine turned on
Blue is 0.18v

Help

ALR2 said:

Brown is 5v - engine turned off
Blue is 0v

Brown is 12v - engine turned on
Blue is 0.18v

Help

Click to expand...

Brown is producing too much voltage when ignition is off.

The question is, where does the brown wire get voltage from initially.?

ALR2 said:

Brown is producing too much voltage when ignition is off.

The question is, where does the brown wire get voltage from initially.?

Click to expand...

Update:
Traced Brown to engine bay fuse box.
(What is telling the brown to wire to remain live ?)
Discovered fuse 2 & 4 kills the power.

Traced Blue to ecu.

Need to research fuse 2 further I think.

From memory. The brown is the main power feed. This is constantly live at battery voltage. The fan is triggered by the control wire (blue?)

Nodge68 said:

From memory. The brown is the main power feed. This is constantly live at battery voltage. The fan is triggered by the control wire (blue?)

Click to expand...

On the other 3 FL1s I have it's live 12v when ignition on, and 0v when off.
But mine is showing 5v when off.
When engine is stone cold.

I would of thought if it was always on constant this would drain the battery prematurely eventually.
Though a thermostat sensor would over rule that, if the engine required cooling after the ignition is turned off.

Either way, there's definitely a fault with the brown cable.
So my next job, is literally running a new brown from the fuse box to the connector, to see if that "solves" it.
I am going to have to assume there's an issue with just the wire. Fingers crossed for tomorrow.

Nope.
Couldn't resist.
Checked 3 freelander fuse boxes (it's getting late.)
All 3 fuse boxes (not wire) the physical terminal where the brown wire comes out, are all showing 0v.
Mine is showing 5v

So, in conclusion, I'm assuming there's a short in the fuse box.
So tomorrow I will swap the entire fuse box.
Let's see what happens then.

Fuse boxes swapped.
No joy.

Next step:
Can anyone tell me where the wiring diagram is for the AUX ?
Or at very least tell me what wire does what?
I can't find it.(though I must have it somewhere)
As I believe one of those wires going in is the culprit.

Top row.
Brown/blue - brown/pink - brown/pink - 5.37v

Bottom row
Brown/blue - 5.37v

(The rest of the wires on bottom row 0v)

ALR2 said:

Top row.
Brown/blue - brown/pink - brown/pink - 5.37v

Bottom row
Brown/blue - 5.37v

(The rest of the wires on bottom row 0v)

Click to expand...

Looking at the wiring diagram , the 1.8 has a simple relay for the cooling fan.

So it's possible the relay is stuck in the closed position.