TD5 limp mode

MatTD5 · Jun 21, 2020

Hi all.
My Dad has a 90 Td5 with manual transmition which has an intermittent problem.
The problem is that after driving through a lot of standing water (only on the road, so not wading etc) the engine goes into limp mode, where it will only tick over, when the throttle pedal is pressed there is no response from the engine.
If left for a few hours the fault seems to 'fix' itself.
He replaced the throttle pedal as they are known to give problems, nothing changed.
No obvious signs of water in electrics etc.
Anyone had anything similar?
Kind regards
Matt

Brown · Jun 21, 2020

Yes indeed. It sounds like some sort of wiring loom fault from the pedal to the ECU. There seems to have been a batch of Land Rover wiring which suffered from brittle conductors and insulation which was apt to chafe through sometime during the mid 2000s. The insulation rubs through on the corrugations on the inside of the plastic conduit they put he loom in. This gives you intermittent faults where the accelerator pedal appears not to work. It may be that the water doesn't help any shorting that is taking place. The loom can retain water for days - or even weeks in some cases - even if it looks dry on the outside.

MatTD5 · Jun 21, 2020

Thanks for your reply.
I guess the throttle pedal wiring is all interlinked with the main loom, or is it a separate loom?

Thanks

Scooby22 · Jun 24, 2020

Is the box under the drivers seat where ecu and relays etc are housed getting water in there.

bankz5152 · Jun 24, 2020

MatTD5 said:
Thanks for your reply.
I guess the throttle pedal wiring is all interlinked with the main loom, or is it a separate loom?

Thanks

Interlinked. However you can bypass the loom with trailer wiring. Wire the throttle direct to the pedal.

However without plugging in diagnostics to find the issue its hard to tell.

resto_d1 · Jun 24, 2020

This happened to me last weekend and she’s booked in Friday at a specialist and will report back. I’ve been running rough since I lost my accelerator but on investigation I have oil in red plug so that needs doing.
There’s a few things that I got from reading Browns and other posts in loom, the main one being rewiring of throttle cable.
The next, and excuse if wrong terminology as I’m not a leccy man, is that the pedal has a tps unit on it and is either 2 or 3 pot.
It takes readings and if these are all over the shop then it messes up your throttle.
As above, only way is to plug in. I have no eml with mine now but mine was after heavy rain and puddles (morning after)

MatTD5 · Jun 24, 2020

Resto: The oil in the red plug is common for sure, however this isn't the issue for me.
I'll keep my eyes open for your response from you regarding this matter.

Kind regards

Matt

resto_d1 · Jun 24, 2020

MatTD5 said:
Resto: The oil in the red plug is common for sure, however this isn't the issue for me.
I'll keep my eyes open for your response from you regarding this matter.

Kind regards

Matt

Yes think the red plug is just an additional on mine and convinced the lack of pedal will happen again. I will let you know what they say. It’s massively off putting and if it doesn’t get resolved it’ll be 300tdi time

MatTD5 · Jun 24, 2020

Indeed, coming from a 2.5 TD it's all a lot more complex!

Thanks!
Matt

Brown · Jun 24, 2020

bankz5152 said:
Interlinked. However you can bypass the loom with trailer wiring. Wire the throttle direct to the pedal.

However without plugging in diagnostics to find the issue its hard to tell.

Yes, that's pretty much what I was going to say. There are examples online of people who've made up their own mini looms just for the driver demand.

resto_d1 · Jun 24, 2020

Brown said:
Yes, that's pretty much what I was going to say. There are examples online of people who've made up their own mini looms just for the driver demand.

I tried looking for this but couldn’t find it on Aussie site etc. I don’t suppose you have a link?

I don’t think you have the vehicle anymore but did you cure yours? It’s really annoyed me as I go fishing lots in remote spots and can’t get stuck by a bloody electric pedal

Brown · Jun 25, 2020

resto_d1 said:
I tried looking for this but couldn’t find it on Aussie site etc. I don’t suppose you have a link?

I don’t think you have the vehicle anymore but did you cure yours? It’s really annoyed me as I go fishing lots in remote spots and can’t get stuck by a bloody electric pedal

It's hard to find the pages I originally looked at with the shifting sands of the internet, but there are a few with some useful discussion
https://www.lrukforums.com/threads/defender-td5-throttle-problems.142192/
https://www.defender2.net/forum/topic65395.html
https://www.aulro.com/afvb/technical-chatter/178486-urgent-no-throttle-response-td5-110-a.html
People talk about it a lot but I don't think anyone's done a step by step pictorial guide
This first appeared shortly after I'd bought the vehicle. The various AA people sent out to see me were under the impression it was the fuel pump. They usually are! The car was then taken on a flatbed truck to a garage who couldn't find the fault because it behaved itself for them. I attempted to drive it home and the fault reappeared at the first roundabout. So I got recovered back to the garage. Then they worked out that it was a wiring loom fault, and I'd need a new one, and then they discovered that they were no longer available so attempted to repair the one I'd got. This served me for another two and a half years or so until another major electronic failure, which required a new loom (this time an aftermarket one) as well as a new ECU, immobiliser unit and a few other bits and pieces. I've still got it. No electronic failures lately, fortunately.

resto_d1 · Jun 25, 2020

Ouch!!! I’m under mine now - just stopped for coffee. I’ve removed ecu and sprayed with contact cleaner, sprayed accelerator plugin, cleaning all earth straps and going to run an earth from ecu. Just did injector harness and cleaned maf and map too. It’s in tomorrow but I want to give them a steer to the cause.
From what I can gather, and I’m no spark, the fault can be found testing continuity between ecu and pedal (provided it is a wiring fault)? They also need to test the reading across the pedal itself.
My problem is eml has cleared and accelerator works now but I know it’ll come back.
Do you know full route of that section? I know the accelerator loom goes up, under dash and I assume through bulkhead. I’m not sure of the route from pedal itself to ecu.
Apologies for thread hijack but think all this will aid op and others

resto_d1 · Jun 25, 2020

Disco, so probably more awkward to do than defender to be fair, but this gent has replaced the section between ecu and pedal. It doesn’t actually look too scary and it probably a 20 quid fix (op has bought a new pedal already)
I think I will do this
https://www.landyzone.co.uk/land-rover/fault-3141-driver-demand-has-been-faulty.302446/

Brown · Jun 25, 2020

Can't remember the exact configuration myself but on my Defender as I remember it joins the main loom and loops around the left hand side of the gearbox. over the transfer box and into the compartment with the ECU under the driver's seat (on a right hand drive car). Yes, the Disco version will be different because I seem to remember on the Disco the ECU was in the engine compartment, wasn't it?

Brown · Jun 25, 2020

resto_d1 said:
Disco, so probably more awkward to do than defender to be fair, but this gent has replaced the section between ecu and pedal. It doesn’t actually look too scary and it probably a 20 quid fix (op has bought a new pedal already)
I think I will do this
https://www.landyzone.co.uk/land-rover/fault-3141-driver-demand-has-been-faulty.302446/

And there it all is in your link, complete with pictures and handy little pins to go in the multiplugs too, for a real Rolls Royce finish. I seem to have missed this completely when i was browsing earlier.

resto_d1 · Jun 25, 2020

Brown said:
And there it all is in your link, complete with pictures and handy little pins to go in the multiplugs too, for a real Rolls Royce finish. I seem to have missed this completely when i was browsing earlier.

It wasn’t obvious as it was labeled up as driver demand and I was searching throttle or accelerator but this came up in pictures.

bankz5152 · Jun 25, 2020

90% of the time the throttle pot wireing wears through above the TX box and tranny tunnel.

An absolute pig to get to.

Best bet is to get a wireing diagram of the ECU identify the throttle wires. Cut and blank them. Then solder new ones in place. Run it however you see fit. You could run it under the floor mats to the pedal.

resto_d1 · Jun 25, 2020

bankz5152 said:
90% of the time the throttle pot wireing wears through above the TX box and tranny tunnel.

An absolute pig to get to.

Best bet is to get a wireing diagram of the ECU identify the throttle wires. Cut and blank them. Then solder new ones in place. Run it however you see fit. You could run it under the floor mats to the pedal.

yeah thing I will mate or along side of tunnel. I don’t even care if it’s on show.
I am fed up with this thing right now as it’s behaving like a Dick.
I have done a thread on my problems elsewhere. Just thought I’d share in here as had same fault as per pm

resto_d1 · Jun 25, 2020

Matt this should help along with wiring diagram in the link I posted above above. If your certain pedal is healthy but getting driver demand error it will be tps related and likely wiring.
If this and the cps are the only things that will strand you it seems mad not to do?!
So....

TD5 limp mode

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