Possible Earth fault causing Defender TD5 issues.

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Tested the throttle pot today:
B & J are paired, White Purple, 5 volt reference feed - both showed a good feed, just under 5v.
D & G are paired, Black Yellow Earth - both showed earth when tested against chassis earth.
Other than that I have no idea how to test any further.
:(

yesterday's AA attempt at communicating with my TD5 was poor to say the least. Got the following error codes:

0091 thru 0095, 0113 & 0120.
 
Ran continuity checks for all three throttle outputs between the throttle plug and the ECU harness plug. All tested as OK. Humph!
 
Id suggest replacing ALL the earth cables coming off the battery. If you have a volt tester check and see if your handbrake cable is live and the seat rails. Sounds stupid but mine where at the time.
 
ratty said:
091 to 094 off the top of my head are extras that aren't fitted to your vehicle such as tacho open load faults, air con and auto box. I can't remember exactly what each one is.

Iirc 113 is a driver demand error and 120 is a communication error to the Ecu, Both of which could be due to the loss of feed from the throttle pot. Check out the wiring on the throttle and there should be a white and purple wire that goes to the Ecu. I believe it is PIN number 14 on the black plug of the Ecu. You could try running a fresh cable between these points and see if that cures it. If that is beyond your capabilities then you could sply try flexing the loom around the Ecu and see if it brings the throttle back. I've had a couple of the wires to my Ecu nearly snap after going brittle.

If the guy brought up the live data and checked the voltage at the throttle pot it would have confirmed or denied this straight away.
Click to expand...

I'll second this. If it's an intermittent fault as vibration makes broken wires make and break contact it may not have been apparent when those people had their diagnostic machines plugged in. If I was you I'd be peeling the wiring loom out of its corrugated tubes, flexing it around, pushing and pulling it and checking for continuity.
 
Unfortunately if only vibration were obvious. It does this intermittently at the 1st ignition switch position. No engine vibration etc. Got an auto electrician coming out tomorrow for a full diagnostic...
 
ratty said:
How did you get on?
Click to expand...

Well the Auto electrician came out, spent three hours on the car and his parting words were 'I have no idea'.

Basically he can see no issues with the earth to the ECU, he has oscilloscoped the pots and they are fine he has been over it with a fine tooth comb and can find no real 'fault'.

Today I took delivery of a NEW pedal/pot assembly - plugged it in and her presto - fault is still there.

I have a 1.5 tonne paper weight stuck in my drive, no hope of finding a fault that is foxing people with more knowledge than me.

I am stumped. The only consolation is that the auto electrician was so embarrassed at not being able to find the fault he didn't charge me (yet!) and the pedal can go on ebay to recoup some costs.

I am at my wits end. :confused:
 
BoredRigid said:
Well the Auto electrician came out, spent three hours on the car and his parting words were 'I have no idea'.

Basically he can see no issues with the earth to the ECU, he has oscilloscoped the pots and they are fine he has been over it with a fine tooth comb and can find no real 'fault'.

Today I took delivery of a NEW pedal/pot assembly - plugged it in and her presto - fault is still there.

I have a 1.5 tonne paper weight stuck in my drive, no hope of finding a fault that is foxing people with more knowledge than me.

I am stumped. The only consolation is that the auto electrician was so embarrassed at not being able to find the fault he didn't charge me (yet!) and the pedal can go on ebay to recoup some costs.

I am at my wits end. :confused:
Click to expand...

Have you tried removing and refitting each of the fuses and relays in turn? Just to make sure that they all have good contacts?

I still think it has to be worth the effort of running a temporary wire from the throttle pot to the ecu just to rule out the 5v feed. Just cos it shows the voltage and continuity it doesn't mean it can carry any load plus it is cheaper than playing Russian roulette buying parts in the hope of fixing the issue.
 
One thing that did come out of the tests was a resistance on the thicker ground that runs to the blue termination plug located in the ECU well under the drivers seat. The resistance climbed as headlamps were turned on. Could be a red herring though.

Any one know more earth points I could have missed.

So far I have cleaned/renewed the following:
Main earth from battery to gearbox, via bodywork.
Double earth to bodywork on the drivers side by the transfer box.
Earth strap from bodywork to drivers footwell.

Any others????
 
You have my sympathies. You have obviously covered the logical reasons for failure.
Although I have little experience with modern engines, after reading the thread again something has struck me - do you have an immobiliser?
I have had issues recently with the one in my Volvo. After research it appears that after a certain age, the internal battery starts to leak onto the circuit board and create all sorts of symptoms.
Just a thought. Hopefully someone else here with TD5 experience can speak with greater knowledge on how an immobiliser would affect things.
 
BoredRigid said:
One thing that did come out of the tests was a resistance on the thicker ground that runs to the blue termination plug located in the ECU well under the drivers seat. The resistance climbed as headlamps were turned on. Could be a red herring though.

Any one know more earth points I could have missed.

So far I have cleaned/renewed the following:
Main earth from battery to gearbox, via bodywork.
Double earth to bodywork on the drivers side by the transfer box.
Earth strap from bodywork to drivers footwell.

Any others????
Click to expand...

by the brake servo in the engine bay
Bottom of the drivers seat box under the ecu
 
Where a bouts in the country are you?

If your near the midlands then try Ian at IRB developments. I can't imagine a really cheap solution but he knows TD5's inside out. If your north of the country then try B.A.S Bell auto services.
 
Shifty1962 said:
Run a temporary earth direct from the battery -ve to the ECU earth point. Also run a heavy temporary earth cable (you can use a boost cable) from the battery -ve to the engine block. If it solves your starting problem then you need to clean and tighten all the main earth points.
Click to expand...
10 years late coming into this thread! Anyway, I had the same problem with my TD5 - intermittent (very) failure to start with the tell-tale 'no ECU light' and the temperature gauge flicking to full deflection at the first key position. A year or so ago, after a tip from another zoner, put a self-tapper through the the seat box to body mount just inside the drivers door which seemed to cure the problem but it has recently returned (ironically on the day it was due to be MOT'd...which did not happen as a result!). For various reasons, I am not able to get under the Landy and work through all the earth connections at the moment - so was contemplating a temporary fix so that, at the very least, I can get it to the MOT station. So, after that very long introduction my question is - if I make up a temporary/emergency earth cable to take the ECU directly to the battery negative (routing it inside the cab), would it be safer to disconnect the ECU earth wire from the terminal in the bottom of the seat box and connect that to the emergency earth cable rather than connect the temporary earth to the seat box terminal (in order to avoid the risk of the light, temporary cable being overloaded by whatever else might try to earth through the seat box as a result of poor connections elsewhere)? BTW, front end of the injector loom has been replaced and the red connector to the ECU cleaned multiple times until the residual oil syphon dried up...so that should not be a contributor.
 
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