Defender TD5 2003 - temp gauge working backwards (ECU?)

[James Mason]

Hi all,

I am a newby to this site and fairly new to a land rover owner. I have a Defender 90 TD5 2003 (pick up) and have been doing various jobs on it. I have one issue that I cannot seem to solve and that is the temp gauge starts in the middle but as it warms up it drops down to cold and remains there. Any pointers? (new gauge and sensor fitted)

I have been looking into it and it seems it may be down to the wrong ECU? has anybody else come across this?

I have check my ECU and it is a NNW004050 (which comes up on a search as a Land rover discovery TD5). what is the correct ECU for a 2003 Defender TD5? 

I have been trying to think as to why the wrong ECU has been put in (if it has?) and was wondering whether it would be due to the fitting of a Clifford Immobilizer? but I don't see why that should make a diffrence.

Thanks in advance

[RedLineMike]

the ecu is set up as a discovery, which is why the temperature gauge works backwards,
 

if you contact https://stormtuning.com

they will be able to assist in getting the ecu set up correctly for your vehicle,

[James Mason]

36 minutes ago, RedLineMike said:

the ecu is set up as a discovery, which is why the temperature gauge works backwards,
 

if you contact https://stormtuning.com

they will be able to assist in getting the ecu set up correctly for your vehicle,

Thanks a lot, I have sent them a message.

[dave88sw]

Happens a lot because Discovery ecu's are far more plentiful and therefore cheaper.  Defenders don't tend to be broken up often so second hand ecu's are hard to find.  Do as above, or fit a matched gauge and sender.  I have found that with a discovery ecu fitted, the engine ecu appears to see the right temperature when looking at live data, so it is simply the wrong signal being sent to the gauge.

[RedLineMike]

16 hours ago, dave88sw said:

Happens a lot because Discovery ecu's are far more plentiful and therefore cheaper.  Defenders don't tend to be broken up often so second hand ecu's are hard to find.  Do as above, or fit a matched gauge and sender.  I have found that with a discovery ecu fitted, the engine ecu appears to see the right temperature when looking at live data, so it is simply the wrong signal being sent to the gauge.

the senders are the same
 

Source:

im using a discovery engine in my defender

[dave88sw]

I'm well aware, what i'm saying is that the Discovery ecu outputs a different signal to the dash gauge but interprets the reading from the sender the same.  Therefore, any alterations to the fueling due to coolant temperature are still happening but the dash gauge will read wrong.  If you simply disconnect the original gauge and fit a new gauge wired direct to a matched sender, you will have an accurate dash gauge and an ecu functioning entirely as it should.  You must leave the original sender in place and connected though, so that the ecu has a coolant temperature reading.

I achieved this by welding a threaded boss to the top hose stub, opposite the original sender and then turning the top hose stub so that one points up and the other down, however, you can buy hose joiners with a boss welded in them for this purpose.

[dave88sw]

The alternative, as said, is to send the ecu away.  i just preferred to do as i said for a couple of reasons; first, the original gauge is not an accurate indication of engine temp, it has no scale and so as not to alarm the driver, it doesn't creep up in normal use, instead it reads "normal", until it suddenly jumps into the red when it's all a bit too late. Second, it's cheaper to fit a new gauge and with Defenders using standard size 52mm gauges, a VDO vision gauge looks original, can be green illuminated and gives a scale in degrees celsius.

[Dave W]

The ECU can easily be changed from Discovery to Defender by anyone with a Testbook or equivalent (did mine with an Autologic one). Only takes a few minutes, just remember to take a note of the injector codes before you start although, that said, it would be worth checking those against the engine anyway. I'd assume that anyone that didn't bother changing the vehicle type on the ECU probably didn't bother coding in the injectors either...