Disco 1 Air Con kills starter circuit!

hi all

I'm new to this forum, so forgive me if I've posted the wrong thing in the wrong place, I'm just after some help with a weird fault!

On the rare occasion that I use my air con I have a strange fault appear.
If I stop the engine (let's say I pull into a garage after 20mins of driving), then try to restart, it simply will not start. Doesn't even try. So all lights come on dash, turn the key, nothing. If left for around 20mins, it will suddenly decide that it is happy again, and start no probs.

I have a few thoughts, and I hoping they will be shot down, but lead me to the actual fault!!!

I am guessing this is a sensor issue, telling the EMS not to start???
I am guessing this sensor is something to do with the auto gear shifter position, as this needs to be in N or Park to allow the vehicle to start???
I am guessing this sensor is either being drowned by the air con fluid drain (loads of water under the car)??? Or it's overheating as its already bloody hot when air con on???

The last time this happened I disconnected the battery, and when reconnected she started, however it took around 20mins of fiddling around with all sorts before I tried this, so may be a coincidence...

Ok, don't be too mean with me... GO!

Perhaps u should start with the model year and the engine that's fitted to your D1 and also why you don't think your vehicle has a issue with the security system (immobiliser) and therefore inhibiting the engine cranking, quote: " doesn't even try"
Not being able to crank the engine could be as simple as an iffy starter motor electrical connection.
The auto selector being in position P or N only before the engine will be able to start, is correct.



Today is POETS day

Sent from my iPad Air on a train.

Apologies 'Discool', I had assumed that the data I gave the forum about my disco would be associated with me/this thread? I'm new, go easy on me bud!!!

It's a 1996 petrol v8 auto 3.9 EX, that's had the gearbox rebuilt, and the engine replaced at some point in its little life.

Im pretty sure it's not security related as the little key light (indicating immobilised), and the little flashing led are all good and off when I try to crank it.

The turn of the key does not cause any change in state, no dimming lights, no clicking relays, it literally is as if the last turn of the key it is not connected to the starter circuit.

I have owned this for 2 years, and it has only ever done this 3 times in that time (once last summer, and twice this summer) with months in between, hence me thinking it is unlikely to be a starter or loose/corroded electrics.
The only common conditions (as I said) are the use of air con and piddling out of loads of water.

Thanks in advance for any help!

Ok now we know u have a petrol u have confirmed my first thought, which is an issue with the immobiliser, the infamous 'spider'.

The problem is a symptom of the an iffy spider, it's something I went through a few years ago, it was slightly different my engine cranked but didn't fire the first this happened was one one day when disembarking from a cross channel ferry, the engine failed to start but after 10 minutes or so and after removing and replaceing coil connections it started and then more more issues for six months then every couple of weeks plus cutting out and firing back up at speed, until it cut out all together at speed and I ended up having the disco recovered back home.

With my issue I found although the spider gave the indication of the engine being remobilised it hadn't therefore still able to crank the engine. So as the spider has two circuits both are the same one removed voltage to the ignition the other removes voltage to the start motor, if this is your issue then if or when it happens again connect al link wire from the battery to the starter solenoid terminal and the engine should turn over.

does the 1996 petrol auto have a spider, I think the TDI auto does not have one but don't know about the petrol.

When mine does this I remove the key from the ignition, lock the car with the fob, then unlock with the fob, this seems to fix it for me.

I had a similar issue with my 96 TDI which I fixed with the £5 bypass plug you stick in the imobiliser plug.

Hi all.

I tried the fob trick last time this happened, as that was my first thought, but made no difference.

I have just ripped out the dash, found the spider, opened it up, resoldered everything and put it all back in...
Phew.
The only casualty appears to be the cup holder mechanism, and I am completely over that!

She certainly starts better now, there used to be a 1 second pause when the key was turned before the starter kicked in, this has now gone! I'll wait for the next hot day and repeat the process of sitting in traffic with aircon on and see what happens.

Thank you all for advice and pointers, and for the old thread I found about attacking the spider.

Ive always hated spiders...