Thread: Ignition electrics problem on D2 Td5

Sparkies gave up on finding source of ignition lights remaining on (or coming back on) after ignition key removed.
They cleaned up all loose wiring to asssorted spotties, old radios etc.
Found that if you depressed footbrake after turning keys off that lights went out and stayed out.
Mechanic at dealer thought he had experienced similar problem in past that came down to failing ECU (The large ribbed aluminium block sitting behind battery). (Think he called it something else though.)
I'm waiting for a replacement 2nd hand and will see what gives, BUT meanwhile removed it and found lots of oil around plugs on the unit.
Cleaned it down and as needed to move car re-installed it.
Found that dash light now come on and go off if you press the footbrake, but come back on soon as you release pedal and now dash "chime" joins in. Undo battery to get lights to stay off.
So might be something to do with that ECU, have to wait and see.
Other LR mechanic reckoned it might be do with the large fuse/electrical unit that sits behind that ECU. We are all guessing.
Seems no way of diagnosing what the problem is.
Car runs and goes well if started. (???)

I have access to a complete D2 Td5 to swap bits over, but it is 1000 k's away (!@#$%!!)

Have you removed the relay /fuse board behind the driver's side dash and inspected it?
It is pretty common to be water damaged fom a leak at the corner of the windscreen, and to cause strange problems.
Regards PhilipA

Vbrab - you also have oil working it’s way down the injector harness to the ECU which then causes all sorts of issues. You will need to replace the harness as well.

Davis Performance claim to have a modified harness to prevent this happening in the future.

So I returned the ECU unit to car as I had to move the car(and I did clean up the oil).
(Cannot believe the oil problem is becasue people allow their rocker covers to leak and then the oil "travels" down the harness...and it certainly has at some time in the past.)
On refitting the ECU, I now find that all lights and the chime now come on when key turned off.
Depress brake, light go out, sound stops.
lift foot off brake and lights and bells resume (no key in ignition).
Starts and runs OK.
Previously if you depressed the brake, the light went out and stayed out (no chime at all)
So disturbing the ECU appears to have done something (not sure it was a positive outcome though).

Talking with 2 LR mechanics from different shops, gets the thought that it is likely the Body Control Unit/module (they have heard of this problem with dash electrics and think that was culprit).
So before I replace the ECU and go through the re-install remap process, I will be changing the BCU as I am told that is plug and play (as it were).
While waiting for one to arrive, I am also going though the under dash fuses and checking that what oil I am seeing about harness and battery area is old oil from a past leak and not ongoing.
Well, what was I going to do with my day off anyway??

Originally Posted by vbrab

(Cannot believe the oil problem is becasue people allow their rocker covers to leak and then the oil "travels" down the harness...and it certainly has at some time in the past.)

Just a point of clarification - it is not the rocker cover that leaks- the oil is forced internally down the injector harness by capillary action to the ECU. It is the harness that fails and needs to be replaced once it is saturated with oil.

I suspect your ECU could also have oil inside the ECU as well now and could be creating short circuits. They can be opened up and cleaned and dried out again but do your homework on this first.

And being an electronic gremlin - can always be something unrelated.....

Originally Posted by DiscoDB

Just a point of clarification - it is not the rocker cover that leaks- the oil is forced internally down the injector harness by capillary action to the ECU. It is the harness that fails and needs to be replaced once it is saturated with oil.

I suspect your ECU could also have oil inside the ECU as well now and could be creating short circuits. They can be opened up and cleaned and dried out again but do your homework on this first.

And being an electronic gremlin - can always be something unrelated.....

I can see I will need a security Torx socket, and possibly static from me could be a problem, but having moved the ECU about and then refitted it I could have spread the oil about inside which may be why I now all the lights and bells.
Giong to try and open it and see if there is contamination inside. At moment vehicle starts and runs, downside may be is that I will lose that if I muck up the ECU .

any tips on opening up D2 Td5 ECU to get oil out...

Note plenty warn not to do this.....but others have done and found oil inside.

I don't know about the "capillary action" story for the inside rocker loom. There certainly is capillary action on the loom from the rocker cover plug to the ECU but once the inside rocker loom has been changed in my case a few cleans of the engine bay loom over a few months and it has not recurred.

I changed mine for a new one 6 years ago and the problem has not re-emerged.

I labouriously modified the old loom by splicing it in the middle of each wire and sealing the plug with araldite. It has been hanging up to dry for 6 years!

IMHO the problem is simply that the plug on the inside rocker loom was not sealed well , as the plug has solid pins which would stop capillary action in it's tracks. The oil fills the connector and then oozes down the wires to the ECU.

The message I am making is that in my experience the problem is fixed with a new inside Rocker loom, and eventually the engine bay loom will clear.



Regards PhilipA
BTW did you remove the inside circuit board and inspect it and the relays on it??