D2 Td5 electric fan always on

**Campaspe Man** · 5th March 2026, 02:34 PM

G'day all,

I feel bad, I've been away from the forum over the summer - working like a navvy outside! Not that anyone would have noticed, but I feel bad!

Ok, the problem. I was doing some minor maintenance on both D2's yesterday and have now noticed that the 2004 Td5 has its small electric fan running full time. Using the Hawk Eye, I've removed any fault codes from both the Engine Management System and the Auto. I've also accessed the fan circuit and can turn the fan off temporarily, using the Hawk Eye. Looking at the live data, the coolant temp was 67 deg, so the fan should not be on.

That said, the live data indicates an active fan request as being On - which it is!

I've done bit of a forum search, and couldn't immediately find a lot, but there was a discussion some years back about oil creep into the ECU.

Any ideas gratefully received!

PS When doing the vehicle check yesterday, I noticed the coolant had dropped a little. Not being able to see anything obvious in terms of a leak, I did see a bit of a wet strip in the area where (what I think is) the coolant temp sensor connects at the right engine font right. I disconnected it for better viewing, but couldn't see any obvious coolant leak whilst the engine was running, so put it back in. The temp gauge seems to be working, and I was able access the guage circuit with Hawk Eye, so I'm assuming this isn't a "since the last time you touched my car" incident! (To quote our German friends).

I should add, I have previously noticed some coolant in that weep hole at the bottom of the water pump, which could explain the coolant drop.

Cheers,
Myles

**Slunnie** · 5th March 2026, 03:06 PM

Is the AC on? I thought the electric fan turned on when the AC was turned on.

Originally Posted by RAVE

Engine cooling fan control
While the A/C system is on, operation of the electric engine cooling fan, to assist refrigerant condenser operation, is
determined by a combination of vehicle speed and external air temperature. When cooling fan operation is required,
the ATC ECU outputs a cooling fan request to the ECM, which then energises the cooling fan relay. The cooling fan
request is output if vehicle speed is 80 km/h or less while the external air temperature is 28 °C (82 °F) or more. The
request is cancelled, and the cooling fan switched off, if either the vehicle speed increases to 100 km/h, or the external
air temperature decreases to 25 °C (77 °F).

**Tins** · 5th March 2026, 03:10 PM

Originally Posted by Slunnie

Is the AC on? I thought the electric fan turned on when the AC was turned on.

That was my first thought as well.

**Campaspe Man** · 5th March 2026, 03:55 PM

Originally Posted by Tins

That was my first thought as well.

Sorry, forgot to say AC off.
My understanding is that the fan comes on under 80km but when the temp is over x degrees. My tests were done under temp.

**Blknight.aus** · 5th March 2026, 04:05 PM

on some flashes of the ECU the electric fan latches on in the event of an overheat.

IIRC its also on a relay which has its main power switched with ignition, that relay may be stuck closed.

**Graeme** · 5th March 2026, 06:09 PM

Back when my D2a was quite new, the fan was always on after I temporarily disconnected the temp sensor which caused a DTC to be stored. LR weren't able to clear the fault so fitted a new ecm.

**Campaspe Man** · 5th March 2026, 06:43 PM

Originally Posted by Graeme

Back when my D2a was quite new, the fan was always on after I temporarily disconnected the temp sensor which caused a DTC to be stored. LR weren't able to clear the fault so fitted a new ecm.

Thanks Graeme. Well, so to build on this theory, I turned the car on whilst the sensor was out, so as to see if any leaks were apparent behind it. Could this have logged a deep fault that is not being cleared?

Any ideas how to access such a fault, if indeed this is it? Could I reverse engineer the circumstances, and trick the ECM?

Myles

PS I have a 2002 donor vehicle. Could I try a temporary swap of the module and see whether the problem appears? Any quick guidance on which module precisely I am taking out?? I'm assuming the one behind the battery?

**Campaspe Man** · 5th March 2026, 07:13 PM

Originally Posted by Blknight.aus

on some flashes of the ECU the electric fan latches on in the event of an overheat.

IIRC its also on a relay which has its main power switched with ignition, that relay may be stuck closed.

Thanks Dave. In relation to the stuck relay idea, would the fact that I can force it off using the Hawk Eye suggest this isn't the cause? And if not, can a stuck relay be unstuck?

Cheers, Myles

**Graeme** · 5th March 2026, 07:23 PM

If the ingition was on with the electrical connector unplugged then a fault would be logged, but such a fault should be able to be cleared. I expect that LR would have addressed mine's issue a long time ago.
Maybe a more LR-specific diagnostic tool should be tried.

**Campaspe Man** · 5th March 2026, 07:36 PM

Originally Posted by Graeme

If the ingition was on with the electrical connector unplugged then a fault would be logged, but such a fault should be able to be cleared. I expect that LR would have addressed mine's issue a long time ago.
Maybe a more LR-specific diagnostic tool should be tried.

Thanks Graeme. Maybe someone will chime in here with some further guidance... I do have more menus in the Hawk Eye to go through - maybe Ill find an error code somewhere deeper inside...?

Thanks,
Myles

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