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OK, what's going on here then?


FridgeFreezer
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After spending a weekend wiring in Nige's 90 with MS'n'EDIS it starts and runs lovely. The only problem is it won't bluddy STOP! You turn the key off and the battery light comes on and it keeps running.

The setup: The only place the new wiring joins the old is one +12v feed for the two relays (Main + Fuel pump) and the switched ignition live that turns the main relay coil on.

The circuit diagram for Nige's setup is here, you can see the two relays and they are connected exactly as shown - there is no other interface with the main loom.

What happens: When you turn the key off the ignition switched live stays at between 4 and 10v (as if it's coming through a resistance somewhere) which keeps the main relay powered up so engine running. It's not back-feeding through the relay as current is always flowing into it not out of it.

What we tried:

Disconnect alternator (no change)

disconnect alt warning light (no change)

disconnect fan belt to alt (no change)

move ignition switched feed to permanent +12v (ISL still puts out +5..10v when key is off)

Disconnect ignition feed from back of ignition barrel (alt light goes out but it still runs on)

Pull each fuse from the fusebox in turn (things stop working but truck keeps running)

Pull each and every other relay in the truck (ISL voltage goes up from ~5v to ~10v as less things are drawing current from it)

A call to Bull Bar Cowboy turned up the fact that 90's of this era have an Ignition Light Resistor in parallel with the battery warning light:

(Just to the left of the alternator on this diagram)

90_to86_diagram.jpg

Which would explain a few things - Nige's alternator is a Mondeo one so doesn't need this, but after an extensive search around the truck and behind the dashboard we can't find the damn thing, if it's fitted <_<

So, does anyone know where this resistor lives or what it looks like, or has anyone got any other ideas that might be causing this? :unsure:

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I've only ever experienced this problem twice and both times it was the ignition switch, although I have heard of this happening and it was apparently the starter motor.

Les.

Funnily enough Ign switch was the other thing I was thinking as I was typing the above!

Jon

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This has got to be down to where you've taken the switched feed from.

When you turn the key off, what happens to the other stuff (radio, wipers....)?

If there were a resitstor in the LR somewhere then this would keep all that stuff powere also & flatten your battery overnight.

I would double check:

a) where you took the IGN feed from

B) there are no shorts on the MS connectors. a short from the IGN to something else could do that.

c) if using the relay PCB, is it constructed correctly? also shorts?

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The feed is 0v with the switch off, and drops to 0v when the engine stops.

The IGN feed is a potential suspect as it comes from behind the dash tray where the central gauge pod is.

The MS would not affect it if there was a short as the only point of interface is the main relay in the MS diagram, and it's coil is the only thing connected. With that feed moved to permanent +12v there is no difference, the engine carries on running until you stall it, and the voltage then drops to zero. The MS holds the fuel pump and coils live for ~2sec after the last ignition event so if it was the MS I would expect the voltage to stick around for a couple of seconds.

There's no relay PCB and the MS connector was checked before being screwed together, although a re-check would prove in case something has worked loose everything is working fine and I would expect to see a fault.

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Well i'm damned! I ran into exactly the same issue with mine (but was too embarrased to post it on the forum :lol: ).

When I switched the ignition off there was about 5 volts keeping the relays open, the alternator warning light flickered dimly and I could kill the engine by switching the rear worklights on! (totally different circuit but figured the mini bulb inside the switch was enough to kill the remaining power).

I figured because everything else on the vehicle was through relays there was not enough load to kill the remaining power, I guessed some power was leaking from the alternator across the ignition switch. Didn't know about the ignition light resistor, mine's a 1986 so will check this out.

Didn't solve it but worked around by powering the whole MS feed from the ignition switched live (not ideal i know)

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Do you by any chance habe a mechanical AND electric fan?

I have known the mech fan to keep the electric one turning and thus turning the fan motor into a low voltage dynamo, just enough to excite solenoids etc.

Lara.

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That diagram is for an oil burner. was the 90 originally so?

Has the IGN feed been taken from the glowplug output of the switch?

It cannot be the alternator causing the problem, as its connect to the battery. any voltage would remain even after the engine has stopped. Unless it is the charge light output....

The resitor is there in that diagram, probably beacuse the output of the alt is 'open collector'. its purpose is to pull the lamp signal voltage up to 12v (lamp off), unless the altenator grounds it.

Try to disconnect the alt charge light lead & then ground it (dash lamp should come on)

Does it stop then?

Hoss

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HfH, that diagram matches the one in my LR defender workshop manual shown as 'Early V8'

(the other diagram 'all models from '86' seems to match my V8 better, which is a '93 model)

Note that theres is no resistor shown on those diagrams. Of course that doesnt mean its not there ;) we know LR chucked whatever bits that were lying around in sometimes :)

Try that experiment of mine. remove & short to ground the (loom side) alternator charge lamp wire. See if it stops.

Hoss

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Note that theres is no resistor shown on those diagrams. Of course that doesnt mean its not there ;) we know LR chucked whatever bits that were lying around in sometimes :)

Do you mean on the V8 Diagram above? part. 63 'Ignition light resistor' is this the same thing?

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Do you mean on the V8 Diagram above? part. 63 'Ignition light resistor' is this the same thing?

Tom

Erm I fink so :huh: I am waiting for electrical grown up to say what next to do, as the dash is already so far apart I reckon with a bit more work I could change the bulkhead :lol:

Hoss,

erm, sorry, can you make you suggestion HFH level, ie consider me a 8 year old when speaking eletrics to me, can you explain what your suggesting and what I am looking for when I do it ?

Nige :blink:

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Do you mean on the V8 Diagram above? part. 63 'Ignition light resistor' is this the same thing?

True, i didnt see that. I dont think its on the post '86 diagram though. Don't have the manual by me now.

Tom

Hoss,

erm, sorry, can you make you suggestion HFH level, ie consider me a 8 year old when speaking eletrics to me, can you explain what your suggesting and what I am looking for when I do it ?

1) Take the charge light lead off of the back of the alternator & connect the lead to ground. leave connected to ground for the following:

2) Start the motor & see if it stops ok when the ignition is turned off.

If it does, its the resistor causing the probs.

If so, I think you can probably remove the resistor - If the later alternators dont need it. I will do some checking.

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IIRC there's a resistor inside some insulated tubing within the loom somewhere between the fusebox & the ignition switch, could be behind the dash tray to the left of the steering column.

look for a fuse holder type part like this one

http://www.vehicle-wiring-products.eu/VWP-...s/photo/inf.jpg

found it in my old main harness, which you may remember I changed recently, the one in that is black with a glass fuse style resistor inside.

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Ralph

thanks.gif

You are a Bl**dy Star,

I will go a huntin' and report back,

although Fridge has removed most of it surgically I will have to be carefull I don't let it out,

or the next prob is I'll have to track down some of this :

smoke2gg3.jpg

I have also got a test to do from BBC, so it may be we have a plan :)

Nige

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Ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo :huh:

Ian G (BBC) suggested I did a test to see what it did......

Basically his suggestion was to ensure the circuit was "Broken",

and this was via his suggestiion of removing the igntion light bulb and try again

So early this morning I scutled into the workshop, lift up dash,

but for time sake I pulled the ligh bar pin unit out (this is a 2.5 inch Plug) that connects dash lights (inc the battery light)

start up :)

turn off :huh:

IT STOPS !

So, I think BBC has once again got the 'spot on answer',

now with Ralphs help of a picture I will be doing a spot of dash huntin, ........

....and will report back........... prob now not till the weekend

Thanks Ian and all - as always :)

Thats just one of the reasons this forum is so damned good !

Nige

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At first I thought that this fault may have been the classic earth loop……………… earths of variable resistance with the current find the path with least resistance to ground ……………… we cannot rule this out quite yet, but there are also other options.

Although the alt tell tale light is a very strange circuit, there is no direct connection to battery live (unswitched) when the ign switch is in the off position, although the test that I asked Nige to do has confirmed that the issue is fairly and squarely in this area. As Tom G has had the same issue, there must be a tie up somewhere.

Looking at the factory diagram, instead of the Haynes book of lies, there is also a possibility around the old ign ballast resistor …………. This picks up cranking live from the starter motor, and also ign switched live……………… the easiest way to dismiss this issue is to look at the starter motor and disconnect the White / Purple feed to the ballast. Although, if this vehicle was fitted with a factory ignition module then the wiring to the starter motor may not exist.

Remember that during the testing I asked Nige & Fridge to disconnect the alt and remove the belt then stop the engine mechanically………… but the problem continues until the engine is stopped ………. This to me points to either an earth loop, or extraneous wiring that is connected to the engine operation.

Mr HFH ………..don’t for one minute think about just pulling the alt tell tale bulb to fix the problem :rolleyes: ……………..that is a bodge and will come back to bite you later ………. We need to get to the actually fault …………and fix it.

:)

Ian

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Mr HFH ………..don’t for one minute think about just pulling the alt tell tale bulb to fix the problem :rolleyes: ……………..that is a bodge and will come back to bite you later ………. We need to get to the actually fault …………and fix it.

:)

Ian

<cough> :rolleyes: Moi ?...think of such a think :ph34r:

The thought never crossed my mind - its still in there :lol:

Nige

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PAv.gif

This post contains violence, threats, and torture

post-22-1185889342_thumb.jpg

What do you mean your innocent ?

Talk damned you talk..........

Tell me everything you know..............

Do I have to get rough then ?..................

post-22-1185889393_thumb.jpg

Right, this is your last warning

Take me to your leader

You ever what to shine again speak now

Resistance is futile..............................................

Nige :blink:

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