Disco dead!!!

Hi all, I have just been messing with brake pedal switch as I have an electrical fault with it, when I tried ignition there is nothing at all, no lights nothing. Central locking locks but won’t unlock, checked all fuses and all ok, brake switch back in place. Any ideas would be appreciated. Thanks in advance

Battery flat, bad earth, loose battery connection, how old is battery.? Cold night can finish them off

freelance said:

Battery flat, bad earth, loose battery connection, how old is battery.? Cold night can finish them off

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Battery ok. 12.3 volts. Disco has been running this morning. Thought I might have earthed something when sorting brake pedal switch but all fuses are ok.

Dean93 said:

Battery ok. 12.3 volts. Disco has been running this morning. Thought I might have earthed something when sorting brake pedal switch but all fuses are ok.

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On a Disco 2, 12.3 volts is NOT OK!.
Charge it up and hope it gets to 12.6 and holds it!

Dean93 said:

Battery ok. 12.3 volts. Disco has been running this morning. Thought I might have earthed something when sorting brake pedal switch but all fuses are ok.

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Fortunately your engine what ever it is will still crank at 12.3v and lower, cranking voltage at the battery can be a lot lower.
But your issue is a dead starting system its it not, or are other main electrical systems not functioning heater, horn, external lighting, wipers for example?

Have u interfered with any thing else electrical under the dash? other than that it’s crystal ball time and something I don't have.

Thanks for that. Battery charged up to 12.8 volts but still the same.

I’d start by checking all battery connections and earths and make sure all good clean contacts

Voltage means nothing...if the ampage is shot then battery goosed...get it drop tested

Double check Fuse 25 in the passenger compartment box and if that doesn't work, disconnect the brake pedal switch and see if it makes a difference.

All things being equal, its something you last messed with... What was the electrical fault with the brake pedal, and did it crank over before you messed with the switch ?

Is there power to fuse 25 in the passenger footwell box ?

Dumb but we've all done it: if auto, it IS in P or N?
And bearing in mind the brake switch relates to the cruise control via an ECU of some sort, is that off?
Best of luck.

scoots said:

Voltage means nothing...if the ampage is shot then battery goosed...

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I tell people this all the time.

As an electrician, volts and amps are linked. Its the basic principle of ohms law... drop testing a duff battery with a load will show a significant voltage drop. But I do agree, an unloaded battery sitting at 12.8 volts means nothing until you load it.

The current that can be delivered by a battery is a function of its capacity (Ah), voltage at the terminals and load + internal resistance. Ah is indicative of the amount of energy stored in the battery, which goes down as the internal resistance increases due to discharge, sulfation and grid corrosion. Internal resistance can be reversed with charging but up to a point and depending on factors such as age, no. of charging cycles, condition of cells, etc. As others mentioned already, the open terminal voltage of a battery does not correspond to the battery's capacity. As an example, if you connect 2 identical batteries in parallel, you will double the capacity (Ah) but not the voltage.

Thanks for all that guys. The car ran and started fine until this point. The fault I originally had was all the dash lights came on when I removed the key. They went off when I pressed the brake pedal but came back on when I released it, unless I kept the pedal depressed for 30 seconds then the lights stayed off. I thought it was brake pedal switch so whilst messing with wiring and testing ignition it just died. Nothing at all. That’s we’re I’m at at the moment. 20 year old disco maybe ready for scrapping.

Dean93 said:

Thanks for all that guys. The car ran and started fine until this point. The fault I originally had was all the dash lights came on when I removed the key. They went off when I pressed the brake pedal but came back on when I released it, unless I kept the pedal depressed for 30 seconds then the lights stayed off. I thought it was brake pedal switch so whilst messing with wiring and testing ignition it just died. Nothing at all. That’s we’re I’m at at the moment. 20 year old disco maybe ready for scrapping.

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Bloody hope not!
All 3 of mine are that age or older!

How old is the battery? if the lights go out with brake lights on I'd say maybe not enough juice to run both.
I had an issue with my old D2 where it would start but the engine would not rev, everything was pointing to the TPS (local ingi guy even said it was the TPS) after running the engine for half an hour while testing it just started working, turned out to be the battery.

If the battery was faulty but showing 12.7 volts the dash lights would still come on wouldn’t they. I understand that it could still have voltage but current could be low under load, I would have thought dash lights would come on and car try to turn over.

Most cars I've owned everything dims when turning over.

backinblack said:

How old is the battery? if the lights go out with brake lights on I'd say maybe not enough juice to run both.
I had an issue with my old D2 where it would start but the engine would not rev, everything was pointing to the TPS (local ingi guy even said it was the TPS) after running the engine for half an hour while testing it just started working, turned out to be the battery.

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The terminal connections on the batt are renowned for being cr@p, real ministry of Cr@ design. The only way I have found of getting them to really connect up tight is to undo them fully, use a hammer and socket to bash the connectors down the posts, then tighten them with the stupid bolt. This might be part of the problem.