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90GTR



Member Since: 05 May 2020
Location: London
Posts: 64

2016 Defender 90 V8 Petrol Works V8 Auto Santorini Black
04 TD5 Yellow Relays - ECU / starting issue - advice please

Recently noticed one of the Defenders (2004 TD5) was cranking, but seemed a tad hesitant to fire up (did fire up, but it was not as immediate it used to be). ECU Injector harness was oil free, however the 2x yellow relays next to it both had some minor blue/green corrosion on some of the pins. This was both on the relay contact points and on the connection point. Figured this could be a cause...

-What do these relays do?
-Any reason as to what would've caused it?
-Best way to clean it?
-Best to buy a genuine relay?


Any guidance of course greatly appreciated - Thank you


Last edited by 90GTR on 17th Nov 2020 10:09am. Edited 1 time in total

Post #865002 2nd Nov 2020 4:45pm
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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 1880

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue

From my head:

The black one is: Glow plugs
1 yellow Fuel pump
other yellow main relay

i don't know the order as mine are not under the seat anymore. Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)

Post #865044 2nd Nov 2020 6:08pm
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dorsetsmith



Member Since: 30 Oct 2011
Location: South West
Posts: 3972


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Post #865064 2nd Nov 2020 7:30pm
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AndyT66



Member Since: 19 Sep 2016
Location: Bedford
Posts: 136

England 2004 Defender 90 2.5 TD XS CSW Zambezi Silver

Dorsetsmith helped me identify the fuel pump relay a couple of years ago. When I turned the ignition on the fuel pump didn't energise and make the whirring noise.


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Post #865105 2nd Nov 2020 9:39pm
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90GTR



Member Since: 05 May 2020
Location: London
Posts: 64

2016 Defender 90 V8 Petrol Works V8 Auto Santorini Black

Thanks all.

Replaced the relays as a precaution and the area was cleaned by a specialist.

Started as it should upon leaving them (and the multiple times they tried, when they finished the above) . However within a few hours the car refused to start. A lot of cranking and it just felt like it didn't want to start.

The next day, it started as normal but developed to an intermittent starting car. Sometimes as normal, other times a lot of cranking.

Had a genuine starter motor fitted last year which is now being replaced to see if it solves the now intermittent starting.

Just wondering if cranking too long can cause the crank sensor to fail? As on one occasion the engine management light popped on after cranking too long and the diagnostic mentioned crank sensor. Although this never appeared again, so find this strange.

Strangely at each time specialist started it since it's worked fine..... Specialist mentioned something to do with a magnetic field???

Any shared knowledge on this appreciated

Post #867874 17th Nov 2020 10:06am
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roel



Member Since: 08 Aug 2009
Location: Lelystad
Posts: 1880

Netherlands 2003 Defender 90 Td5 PU Caledonian Blue

Is your battery still good enough? From experience I know that you need a voltage above 8.5V? for the ECU to work. The starter motor will crank the engine but the injector will not give any diesel.

Injector seals can also give starting problems. Is your engine oil level rising? Roel

1984 90 2.5 na Diesel - RR V8 (1994-2001)
1997 Camel Trophy Discovery 300TDI (2001-2009)
2005 G4 Discovery III 4.4 V8 (2008-2018) It's gone but it still hurts.
2003 90 Td5 (2009-now)

Post #867890 17th Nov 2020 12:03pm
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landroverdiver



Member Since: 13 Jun 2009
Location: Johnstone
Posts: 167

Scotland 2004 Defender 110 Td5 SW Zambezi Silver

I'm far from expert, but I will share my own starting issues (2004 TD5)

oil in injector loom - replaced loom and cleaned ECU with contact cleaner

replaced all 3 relays - OK for a while, however I had used non-genuine parts and starting problem returned. I have now replaced with genuine parts and so far so good.

an obvious indicator of problems for me was when I turned the ignition key, if the temperature gauge immediately went into the red, then I knew I had a problem. With the relays, a temporary fix required some manual jiggling before normal starting resumed

Post #867909 17th Nov 2020 2:58pm
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LandymanStefan



Member Since: 30 Aug 2017
Location: Surrey
Posts: 588

England 2001 Defender 90 Td5 SW Epsom Green

I had a crank no start issue at the beginning of the year. I bought a nanocom diagnostic tool, it wasn’t receiving a crank speed. I changed the cranks sensor, same problem, I bought a stand alone loom from Martin to run from the crank sensor to the ecu as the original wiring was pretty Censored . Same problem. Only thing left was the ecu. Bought an NNN ecu on eBay for £200 problem solved. I had one previous start issue before this moment where it’s spluttered then eventually fired but I drove home with the check engine light on.

Post #867945 17th Nov 2020 7:10pm
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MGCarr



Member Since: 18 Nov 2016
Location: Lancashire
Posts: 58

United Kingdom 1997 Defender 90 300 Tdi PU Rioja Red

Had a similar problem on a friend’s car which had us scratching our heads for quite a while until,more by luck than good judgement, we found that one of female spade terminals inside the multi-plug to the yellow relay had spread open and was making an intermittent contact

Post #867967 17th Nov 2020 8:44pm
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90GTR



Member Since: 05 May 2020
Location: London
Posts: 64

2016 Defender 90 V8 Petrol Works V8 Auto Santorini Black

Thanks all, I've certainly learned a lot. A lot of worthwhile checking was carried out on the car so no time wasted.

Well to put it to bed (for now......) new non-genuine starter motor has solved it. A considerable amount of starts throughout the past 24hrs in a range of scenarios and well it works just fine... I trust the car again. So much so, its been sent off to Swissvax so I can use it through the winter...

Genuine JLR starter motor lasted approx 1 year less than 7k miles.... so have gone with the company's recommendation along with their guarantee to warranty it all for longer than that....

Post #868891 21st Nov 2020 11:10pm
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LANDROVER



Member Since: 13 Feb 2016
Location: EAST OF ENGLAND
Posts: 180

United Kingdom 

Sounds like you have cured your problem.

If you get a occurrence my advice would be fit an additional earth from the battery Negative post to the earth post where the ECU is and the yellow relays are under the drivers seat.

I did this after advice from this great forum and my problems went away.

I had long cranking and intermittent non start.

I changed all the relays and the plug bases and crimped in the new plug bases and it turned out to be the earth issue which seems quite common.

I would suggest this if other users have these issues as a first attempt to fix as it's cheap and easy. Thumbs Up

Post #869059 22nd Nov 2020 9:42pm
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