Disco 1 Electrical Gremlin!

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currymunster

currymunster

Well-Known Member
Posts
796
Location
Folkestone, Kent.
Hi every one, hope you've all had a good start to the year.
I have a problem I'm hoping you may be able to help with.
1999 disco 1 300tdi manual
Car stood for 3 weeks to do MOT welding.
Flat battery
Jumped it
Drive a couple of miles to finally get an MOT.
Got to the garage and the right hand indicators are permanent on. Not flashing. Just on, as well as the dash tell tale light for the indicators.
Only way to turn them off is to disconnect battery.
I've done the MFU diagnostic test and all is fine.
I don't think it's the hazard switch as I've swapped it and no difference.
Also I removed the plug from the infivator stalk and they all started on
Worked out fuse 12 turns off all the RH indicators and dash warning light.
Found out that allegedly fuse 12 is for MFU and specifically the key switches in the doors.
I remembered that when battery was flat I unlocked the doors manually and maybe they needed locking/unlocking with the key to sync them back.
Low and behold I locked with key, then unlocked, then locked again and unlocked with the remote. I then locked with the remote and they all went off except one.
The ones that went off are the dash warning light, front right indicator, rear right indicator.
So, for some reason, the side repeater says on permanently. I can remove fuse 12 and it goes off without effecting anything else.
I've removed the bulb for now.
Strangly the indicators work fine and they flash at the normal rate even though the bulb is removed??
The other thing that's changed is when I lock with the remote, the indicator's flash 3 times as usual but when I unlock with the remote. It unlocks fine but the indicators do not flash once like they used to??
Immobiliser appears to be fine.
It starts and drives no problem.
But it's not going to pass an MOT with the repeater on permanently.
I really don't understand how it can just be the side repeater on the drivers side?
I thought they were all connected so surely they would all come on?
I'm guessing the alarm theft module??
It was damp in the passenger foot well. Looks like the heater inlet may be leaking
Sorry for the long post ...
Anyone any ideas??
 
Have you tried removing pin 1 C274-1 on the alarm module to eliminate the alarm firing the righthand repeater
upload_2023-1-16_12-37-49.png
 
mystery said:
Have you tried removing pin 1 C274-1 on the alarm module to eliminate the alarm firing the righthand repeater View attachment 281488
Click to expand...
That is a really good diagram. I've only got a black and white one from the 1995 electrical workbook.
I haven't tried removing that pin but I can. That looks like it's connected to the front indicator as well??
It also looks like it's connected to the MFU as well on connection K?
I do know that if I remove fuse 12 on the MFU it turns off and if I unplug the connector on the back of the MFU it turns off.
I could swap the MFU as the only one I've got is black and mine is cream. I did try it and there was no change but the rear fog lights came on permanently which I assumed is down to it being the earlier type and not compatible..
I have removed that whole plug and the other one and connected to the alarm module and it stays on??

I'm give it a try but not sure how soon I can do it
 
Last edited:
Ok, starting with the MFU, fuse 12 is its fuse but the indicators is fuse number1. plus at the moment I don't have any idea on the MFU relationship with the alarm or indicators.
You found the correct way to synchronise after the battery disconnection, unlock with key then press the fob lock button four times.

As u thought correctly, both indicator repeaters are supplied in parallel and also to ground with the front indicators on each side.
The bulb fitted in the repeater is only 5w so very low current draw.

The security ECU controls the unlock and lock hazard signal and as a built-in feature indication the the fobs battery is failing u will find that on disarm the single flash won’t flash, also the need to press the unlock button twice is required.

Finally I don't see why the r/h repeater bulb is illuminated but the main bulb isn’t. It doesn’t make any difference normally, but the repeater bulb is an LED by any chance ? If so fit a replacement.





Sent from my iPad on a train
 
Last edited:
currymunster said:
rear fog lights came on permanently which I assumed is down to it being the earlier type and not compatible..
Click to expand...

You are correct IME.

currymunster said:
That is a really good diagram.
Click to expand...

+1 - @mystery 's diags are superb. Certainly tak the Mystery out of the job..:)

currymunster said:
Flat battery
Click to expand...

3 weeks seems a relatively short time to go flat ... battery OK?

Have you checked all the earths for the indicators..? with a wander lead as necessary ... the side repeater wiring on our '97 D1's is not the best - the covering of the loom seems brittle - could it be allowing a short ? The 95 scrapper I have seems to have better, more flexible covering :confused: ...
 
discool said:
Ok, starting with the MFU, fuse 12 is its fuse but the indicators is fuse number1. plus at the moment I don't have any idea on the MFU relationship with the alarm or indicators.
You found the correct way to synchronise after the battery disconnection, unlock with key then press the fob lock button four times.

As u thought correctly, both indicator repeaters are supplied in parallel and also to ground with the front indicators on each side.
The bulb fitted in the repeater is only 5w so very low current draw.

The security ECU controls the unlock and lock hazard signal and as a built-in feature indication the the fobs battery is failing u will find that on disarm the single flash won’t flash, also the need to press the unlock button twice is required.

Finally I don't see why the r/h repeater bulb is illuminated but the main bulb isn’t. It doesn’t make any difference normally, but the repeater bulb is an LED by any chance ? If so fit a replacement.
from my iPad on a train
Click to expand...
Hey Discool,
Lots of info there, thanks
I will change the battery on the fob and see if the indicators flash on unlock. I did test the battery with a multimeter and it was over 3v but not by much. 3.1v I think. I assumed that was okay but clearly not.
I knew the alarm module did the flash on lock and unlock as you can see the two relays inside which click when it's inertia cuts in.
I also bypassed the whole module on my old 95 but I don't believe it's quite as easy on this as there is no spider. It's all in the alarm module.
As far as the bulb goes out isn't LED so yes, it's rather confusing.

Disco1BFG said:
You are correct IME.



+1 - @mystery 's diags are superb. Certainly tak the Mystery out of the job..:)



3 weeks seems a relatively short time to go flat ... battery OK?

Have you checked all the earths for the indicators..? with a wander lead as necessary ... the side repeater wiring on our '97 D1's is not the best - the covering of the loom seems brittle - could it be allowing a short ? The 95 scrapper I have seems to have better, more flexible covering :confused: ...
Click to expand...

Thanks,
The battery was new from the last owner I think last year but that's not too say they didn't swap it before they sold it. I just have the receipt for it with a new alternator....
It seems to be holding is charge now and starting okay. I will check is voltage.
 
currymunster said:
with a new alternator....
Click to expand...

I was going to ask if you had a new alternator, because, sadly, IME, you need to be super careful of the set point - a new alternator on my D1 with a way too high set point fried my MFU, and damaged my alarm ECU too.. The alarm is repairable, the MFU is not. Remember that the MFU is old, and was made by the Prince of darkness..

I saw 14.7 v, which rose to 15.4, and then climbed to 19.2 on the over-run - hardly any wonder that the MFU was fried.. I fitted Hitachi regulators to both our D1's - set point is 14V - and it falls on the over run..
 
Well, your not going to believe this, it's fixed itself!
Just got home from work and on the off chance I put the bulb back in thinking I'd check the two connectors.
It didn't come on. So I put the hazards on and works fine. Popped the ignition on and it works fine. All flashing as it should and not staying on. I've driven it to work today and yesterday. 200 miles so I'm guessing it was water somewhere and it's dried out?
Fob batteries ordered....lol
 
Last edited:
currymunster said:
Well, your not going to believe this, it's fixed itself!
Just got home from work and on the off chance I put the bulb back in thinking I'd check the two connectors.
It didn't come on. So I put the hazards on and works fine. Popped the ignition on and it works fine. All flashing as it should and not staying on. I've driven it to work today and yesterday. 200 miles so I'm guessing it was water somewhere and it's dried out?
Fob batteries ordered....lol
Click to expand...
Well it was a strange electrical issue and now stranger in that it disappears.
Was it just a dream :D and hopefully now wont return.
 
currymunster said:
Let's hope so.
I can only assume there was some damp in the header plug mention above and it was allowing a current to get into the green and white wire.
Cheers
James
Click to expand...
Well it’s not having to carefully removing and then refitting the black stuff thats in the footwell underneath the glove box to enable to get access to the header makes u a winner.
So now go and buy a Loto ticket :D
 
discool said:
Well it’s not having to carefully removing and then refitting the black stuff thats in the footwell underneath the glove box to enable to get access to the header makes u a winner.
So now go and buy a Loto ticket :D
Click to expand...
It's already removed...lol
I just put it off until daylight. Which looking at work at the moment won't be till the week after next............
 
mystery said:
Check for water ingress at header HJ6View attachment 281525
Click to expand...

Well,
Thanks mystery.
Because of you I've found the problem, and boy was it a problem.
It most definitely was the header plug and I'd never found it without your help.
It was actually under all the fabric like wrapping they had wrapped around the loom
Still wet. The water had gone down the loom and was sitting there and not drying out. It was a right mess
I ended up cutting the wires and removing it. Solder the wires back and now it working again.
Yes, it had gone wrong since the last post.
It joint all the green and whites together(offside)
All the green and reds together(nearside)
Then two purple wires which were constant live which is where the power was leaking from with the water.
I'll put a photo up.
Everything is working great now. Just got to find the Leak.
Windscreen...... Heater intake...... Sunroof........
I've already siliconed the sunroof frame up.
Thanks also to Discool as I'd not have worked out the fob battery flat.
Thanks guys
 
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