Disco 2 Starting Issue

Hi all. D2 TD5 Manual, 2001. Having not been used for six months, with all that wet and cold weather, tried to start Landy. WOW !! The engine turned and started immediately on key position 2, ie Should have been ignition only.... Also making an unusual noise from running engine, so switched off quickly !
Could problem be with ECU, or am I looking at starter solenoid fault ?
With engine running, nothing electrical seems to function. Ie no seat or window control when selected.
Dried out moisture on ecu connectors etc, but the thing still starts on the wrong key position.
Any ideas folks ? I am stumped. Do not know where to start on this one.
Dave

If you are handy with electrics and you have RAVE i'll give you some troubleshooting hints

OK on the Rave. I have a Hawkeye but it has not helped in this problem.
Hoping someone can steer me in right direction eg Ignition switch, solenoid, a relay, or ECU perhaps OMG...........
Not really sure where to start.
Thanks
Dave

When i name a connector see RAVE-Electrical library-connector views for it. First test which will reveal things is to leave the ignition off then go to C0028(front of the interior fusebox) and give feed with a wire in the plug from behind into pin 5 (yellow wire) and ee if it cranks this way or not.... according to this result we'll go further

Hi folks. Been a few days since starting this thread. Anyway finally got it sorted.
After a lot of testing with DVM traced this fault to a sticking relay in starting solenoid circuit. Relay in box under driver dash was sticking, so replaced with new and all fixed!!!!
Thanks all who replied with help.
Dave

That's strange cos there's no relay connected to the starting circuit whatsoever, those relays are for the indicators and rear window motors, eventually DRL's so if you jiggled with that fusebox better prepare yourself with another cos the fault might be within it

Yup, your dead right. Fault is back......
Perhaps water ingress dried up a bit, but is now back causing problem.
Studying the circuit, and after much measurement with DVM and continuity meter, I have eliminated the ign switch, the ignition relay (which is in the engine comp fuse box), and the under dash fuse box.
I am left with suspecting the BCU, which is required to supply an earth return for the fore mentioned relay, to switch power to starter solenoid.during ign switch in cranking position only.
So I reckon I am looking for a short to earth within the bcu, causing the engine to start when key is in position 2 ie IGN. only.
Arggggg................
Will continue tomorrow by removing bcu !!!!
Thanks for all suggestions folks.
I will report back on progress.
Dave

DaveMac said:

Studying the circuit, and after much measurement with DVM and continuity meter, I have eliminated the ign switch, the ignition relay (which is in the engine comp fuse box), and the under dash fuse box.

Click to expand...

How did you eliminate the interior fusebox though? ....cos according to the next statement of your's you didnt undersdtand well the circuit and at this point that fusebox or ignition switch is still suspect

DaveMac said:

So I reckon I am looking for a short to earth within the bcu, causing the engine to start when key is in position 2 ie IGN. only.

Click to expand...

IMO you should have followed my plan from the beginning cos you are on the wrong path... the BCU can't provide crank feed for the starter relay, it's managing only the earth on the relay's coil for immobilisation purpose so even if you connect this wire to earth or it has a short it will not activate the relay, the live for the coil is coming from the interior fusebox and it's not supposed to be live without the ignition on crank position what so ever. .... if you decide to believe me start again from post #4 and i'll help you

OK Let me get this right. With ign switch in off position, ie key out, you want me to wire a live 12v feed, from battery +, to pin 5, yellow wire on the fuse box connector, leaving this connector in place. Is that correct ?
Sorry if I did not follow this after your original reply. I am really grateful for your input.
Thanks
Dave

Yes; that's the plan cos the yellow wire is only for ignition pos II(which you said it cranks on it) and if it will crank this way then it's a short within the fusebox or wiring, or even switch between the pos 2 live and crank live if you see what i mean

so if it cranks this way unplug that C0028 and give feed to pin 5 on the fusebox that way

A correction for the previous post, you have to unpin that pin 5 and do the trick with feed into that port with ignition turned to 2...or if it cranks this way with the yellow wire undone the fault is found(make sure the yellow wire doexnt toiuch earth), it means it's a short in the switch, if it cranks with unpinned Y wire and external live to cavity 5 then the short is in the fusebox or wiring beyond it... sorry, i neglected that without ignition on 2 the BCU doesnt complete the relay's earth path so it will not crank at all

OK Thanks for clarifying the role of BCU, in regard to earthing for immobiliser etc. BTW I have already checked the ignition switch, by removing ign switch and checking the switch contacts. All seems ok in as mutch that, the W/R wire from the switch gets shorted to the N wire (+12v feed), only when the ignition switch is turned to the crank position.
So it looks like the fault is in one of the fuse boxes, if I am not mistaken.
Happy to carry out your suggestions, if you have the time to carry on helping.
Regards
Dave

I'll not let you down on this no worries... a dogged devil i am

sierrafery said:

I'll not let you down on this no worries... a dogged devil i am

Click to expand...

OK Thanks sierrafery for being so patient!!
I am very reluctant to keep canking the disco with this fault, and possibly causing more damage re starter etc when it starts.
I have found the direct lead to the solenoid coming out of the engine fuse box. A thick N/R (brown/red) lead. If I disconnect this connector and put a voltmeter on the outlet of connector I can read whether the solenoid would be getting energized, with +12volts. Is it OK to carry on investigation like this or do I need the engine to actually crank over and start?
Just by chance I have found that removing F29 fuse, cabin fuse box, no +12volts appears at this connector, on any position of ign switch.
Does this point to the faulty areas ? Maybe BCU ?
Anyway thanks for help.
It is absolutely peeing down here in South Scotland, so looks like I will continue with this tomorrow, Thursday.
Regards
Dave

It's OK to investigate by checking the voltage at the solenoid wire but dont remove fuses just like that, F29 is the feed for the BCU and you dont get feed to the solenoid cos the BCU doesnt complete the earth path to the relay's coil, it's like immobilised....forget about the BCU it's not your problem, as you well presumed in a previous post it's a short in the interior or engine bay fusebox, do that test with pin 5 cos it will be relevant

OK All noted.
Will give it a try tomorrow.
Dave

Hi serra ferry,
Disconnected yellow wire at the fuse box connector pin 5 (it comes from ign switch) leaving others on the connector and plugged into fuse box.
Turned key through all positions. No cranking volts to solenoid, but some clicks from around vehicle etc as normal.
With switch in position 2 (ignition only) connected +12v from battery to vacant pin 5 on fuse box.
Immediately 12v appeared at solenoid feed, and also I can hear the fuel pump running.
Removed 12v wire and pump goes off and 12v disappears from solenoid feed.
What does all this mean now ?
Regards
Dave

OK, we are close to the answer, unpin the crank wire from the plug too,(WR from pin 6) then do the test again with feed to pin 5 and key in pos 2... if this way there will be no 12V to the solenoid it's clear that the short is within the ignition switch/harness if you'll get 12V with pin 6 undone as well the only move left is to replace the interior fusebox

OK
Did that. Exactly the same. 12v to solenoid and pump running.
Conclusion ?
Dave

Final conclusion: Replace the fusebox, or remove it, open it and inspect it maybe you can see where's corrosion in it but even if no visible sign now it's clear that it's a short somewhere between the ignition feed and crank feed circuits and this fusebox is quite common to make all kind of tricks so it shopuld be ruled out before going further... the short can be in the wiring or in the engine bay fusebox too but interior fuseboxes are not so expensive second hand and the troubleshooting to rule the thing out 100% implies removing both fuseboxes and make more measurements with other unpinned wires... i'ts not hard for me to tell you what to do but it can be a nightmare for you.... do you want to go this way?