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excossack



Member Since: 22 Feb 2012
Location: North West
Posts: 4402

United Kingdom 1999 Defender 110 Td5 SW Caledonian Blue
TD5 temperature gauge fluctuating

This morning did a 95mile trip to the rally venue - all good. Drove home tonight and the temp gauge started to fluctuate while driving along.
It first happened about 5 miles after climbing a hill. I found a lay-by and pulled in.
Expansion tank hot, hoses all OK, no sign of any water leaks or steam and no steam out the exhaust
No loss of power, or odd engine noises and no warning lights on the dash,

This happened about another 4 or 5 times on the way home. Journey was 45mins since first odd moment,

Here is a video on YouTube of the gauge - best press mute or you will get road noise etc

&feature=plcp

Any thoughts people? 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?

Post #181803 3rd Nov 2012 10:34pm
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bob neville



Member Since: 30 Apr 2009
Location: somerset
Posts: 3232

England 2001 Defender 90 Td5 SW Epsom Green

Clean the contacts on the sensor and check for any signs of chaffing on the wires.

Gauges normally use a common ground so worth checking that.

Other things it could be - thermostat stuck open, sensor shot, air in the system (open the valve on the top hose etc.)

Good luck

Bob 2015 Jaguar XE240 R Sport - goes like ....... !!
2013 Defender 90 CSW - sold
2009 Defender 110 Double Cab - sold
2001 TD5 90 CSW - offroad project - sold to a forum member
2011 Porsche Boxster - for the sunny days !

Post #181809 3rd Nov 2012 10:57pm
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Laurie



Member Since: 22 Feb 2008
Location: Sussex, England
Posts: 2871

England 2005 Defender 90 Td5 XS CSW Bonatti Grey

Make sure your radiator(s) is clean.
TD5 Rads can only just cope. 

Post #181811 3rd Nov 2012 10:59pm
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jasong4110



Member Since: 19 Oct 2009
Location: Henley On Thames
Posts: 268

United Kingdom 2003 Defender 110 Td5 G4 LE Java Black

I would say it's possible you have an earth fault, mine started doing this I went through all the wires etc and then ran a new earth to the bulkhead which sorted things...

However as on a run TD5's normally sit in the middle it could be the sender although this is very uncommon.

Jason.

Post #181815 3rd Nov 2012 11:06pm
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Lou Sparts



Member Since: 15 Apr 2012
Location: Kent
Posts: 1501

United Kingdom 2005 Defender 90 Td5 XS CSW Zambezi Silver

I had a very similar problem on my Turbo Diesel years ago so swapped the sender (twice) tried a known good sender from a mates vehicle all to no avail so ran a new engine earth wire to the chassis and no more problems for the 5 years i owned it.Hope you get to the bottom of it soon. 2005 Td5 90 XS

Steve

Post #181816 3rd Nov 2012 11:17pm
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diesel_jim



Member Since: 13 Oct 2008
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Posts: 4898

United Kingdom 2006 Defender 110 Td5 SW Epsom Green

Check the earth on the ECU.

Post #181821 3rd Nov 2012 11:34pm
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excossack



Member Since: 22 Feb 2012
Location: North West
Posts: 4402

United Kingdom 1999 Defender 110 Td5 SW Caledonian Blue

Had a quick look this morning.
No loss of water
Wiring to the temp sensor looks OK.
Checked wiring at the back of the gauge and that looked OK.

Where is the ECU earth cable ? I had a quick look but could not see it.


Will check the rad and remove the air lock screw in the top hose.
Does the temp gauge take its reading from the ECU via the sensor in the top hose (RHD side front of the engine) or is there a separate temp sensor the gauge? 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?

Post #181920 4th Nov 2012 11:55am
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wslr



Member Since: 18 Jul 2010
Location: Wellington, Somerset
Posts: 581

United Kingdom 

It's a strange one, and interestingly I had someone give me the exact same description of an issue last week.

It could be the earth, or a wire being pulled tight as Jim says. Probably a good start point. You'll ideally need to unbolt the ECU and fuse box under the driver seat and just check the earth wire bolted to the bottom of the under seat box firmly. May even be worth removing and cleaning anyway. Also, on some I've seen the main loom being pulled tight through the under seat box (it heads off towards the transfer/gear box). However, when you get these, usually (not always) the gauge hits the red and the engine will cut out. So Jim's earthing is a good place to start as it is a minor fluctuation.

Are you getting any other electrical issues, such as hard starting in the morning or the lights fading in and out?

It may then be worth checking everything else is OK in the cooling system - Thermostat/pump etc.

Post #181923 4th Nov 2012 12:07pm
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excossack



Member Since: 22 Feb 2012
Location: North West
Posts: 4402

United Kingdom 1999 Defender 110 Td5 SW Caledonian Blue

With the engine running, I had a look in the header tank and no bubbles. Still with the engine running I removed the airlock thingy in the top hose and got a goods squirt of water out straight away - which to me means the water pump is OK and no air in the system?

No probs on the checking/cleaning the earth on the ECU I might even run an extra earth direct back to the battery.

No other electrical issues, no hard starting. I'm now waiting on the the glow-plugs as its gone colder (when warm I can just jump in a turn the key)
Lights are not fading

Now do you check the pump?. The stat I would have to remove and if I am doing that I may as well replace it.? 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?


Last edited by excossack on 4th Nov 2012 12:19pm. Edited 1 time in total

Post #181928 4th Nov 2012 12:17pm
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T1G UP



Member Since: 08 Dec 2009
Location: Bath
Posts: 3101

England 2011 Defender 110 Puma 2.4 XS CSW Orkney Grey

I had oil in the ecu and I had an issue with the blue loom crimp in the ecu area making a intermittant earth fault. Do the guages flick about on start up?

Also consider battery voltage as TD5s hate a weak battery

Post #181929 4th Nov 2012 12:18pm
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diesel_jim



Member Since: 13 Oct 2008
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Posts: 4898

United Kingdom 2006 Defender 110 Td5 SW Epsom Green

excossack wrote:

Where is the ECU earth cable ? I had a quick look but could not see it.





You can just knock another "extra" on up.... use a ring terminal, crimp it to a piece of cable. bolt it under one of the ECU mounting bolts, then run it to a good earth point (ideally out the back of the seatbox following the battery cable (that runs the fusebox) back to the battery and straight onto the -ve terminal, but failing that a good body or chassis earth point will do. There are a couple of studs riveted onto the inside floor of the ECU underseat box, usually with a plastic cap on; this would be better than nothing)

Post #181930 4th Nov 2012 12:19pm
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excossack



Member Since: 22 Feb 2012
Location: North West
Posts: 4402

United Kingdom 1999 Defender 110 Td5 SW Caledonian Blue

Checked the red plug an no oil. Well none since I replaced the loom about 3 years ago.
I did see the blue plug thing and was going to ask what it was for. 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?

Post #181932 4th Nov 2012 12:22pm
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excossack



Member Since: 22 Feb 2012
Location: North West
Posts: 4402

United Kingdom 1999 Defender 110 Td5 SW Caledonian Blue

T1G UP wrote:
I had oil in the ecu and I had an issue with the blue loom crimp in the ecu area making a intermittant earth fault. Do the guages flick about on start up?

Also consider battery voltage as TD5s hate a weak battery


The gauges don't flick about on startup.


It happened again yesterday on the way home drove about 30 miles all OK and then drove home in the evening again about another 30miles and then the gauge started doing its little dance, but not as much. Then it settled down for the rest if the trip. 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?

Post #183961 11th Nov 2012 11:17am
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excossack



Member Since: 22 Feb 2012
Location: North West
Posts: 4402

United Kingdom 1999 Defender 110 Td5 SW Caledonian Blue

Looking at the wiring diagram in the Haynes manual and it looks like there are two coolant temp sensors?

Wiring Diagrams
13.25 Diagram 3 item 32 - Coolant temp sensor with 2 wires. Pink/Black and Pink/Green feeding the ECU on terminals c158/8 and c158/7

13.27 Diagram 5 item 52 - Engine Coolant temp sensor with 2 wires. Green/Blue (then changes to Light Green/Blue) and Earth feeding the instrument cluster on terminals cc1052/2. Earthing on terminal c1052/1 to point earth point E2 and a wire from c1052/3 to Fuse 15, passenger fusebox.


So are there two temp sensors?
Is the passenger fuse box the one behind the gear stick? 1999 Defender TD5 110

Regards
John M0VAZ
Do you know what a nemesis is?

Post #184104 11th Nov 2012 8:56pm
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landyman37



Member Since: 22 Jan 2012
Location: west midlands
Posts: 151

Do you have a pic of the diagrams

Phil

Post #184955 14th Nov 2012 11:40am
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