10P Defender cut out and binnacle gauges went mad

Sat in the Defender earlier talking to my mate as we’re leavong work I had the engine running and we noticed the voltmeter was only reading 13.5v despite a new denso alternator a few weeks ago, revved the engine slightly and no change. Thought no more of it, then about 30 seconds later it just cut out and all the gauges in the binnacle went mad. Switched off and started again fine.

I suspect possible a loose ecu plug or perhaps a wire in the plugs or something so I’ll check all the in the morning, but just wondering if anyone else has had anything similar??

Nothing obviously amiss, it did it again today. Switched ignition on, wiered groaning noise from binnacle and gauges going mad. Switched off and on a couple of times and it was fine all day.

Can’t find anything similar about it, anyone have any ideas?

Check the plugs going into the ecus for oil ingress. Check the relays near the ecus as well, remove and clean the terminals. Check the earth next to the relays too, remove clean retighten. Easy and cheap to try first.

Check if the receptacles in socket of the main relay are tight enough, that relay used to get loosened, it's C0063 in the attachment

Sounds like a dogey earth. Check them all!

Managed to get a video of it this morning.....

tom1979 said:

Managed to get a video of it this morning.....

Click to expand...

check all your earths and connections check and swap the relays incase of a lazy relay also spray the relay box with wd40 incase there is some slight moisture

Relay knackered

I put the old ecu back in and haven’t had any problems (touch wood).

As the problem didn't reoccur with a different ECU I sent the ECU off to be tested and no faults were found. I have reinstalled it and it seems to be fine so far after a few days. Very strange indeed! I may replace the relays anyway, are they just standard relays? I cannot find part numbers for them

Little update. Took it down the car wash they rang up to say they couldn’t start it. Had a look and the corner of the fuse box was red hot, any ideas? The relays aren’t hot

Had another poke around and found one of the connections on the fusebox was loose and causing the heat. This also momentarily caused a similar issue to before with the gauges so I suspect it is all down to this loose connection

I had similar symptoms back in 2015 and it turned out to be the large positive terminal on the alternator whose nut had come loose. Puzzled me at the time but the AA man who came out for me guessed it was an alternator problem straight away. The battery warning light on the instrument console is fed by a separate wire in the multiplug on the back of the alternator so that you don't necessarily get a charging warning light when this happens.

It turned out to be the loose connection on the fusebox on the wire coming from the battery to the fusebox. Cleaned it all up and refitted and it has been fine ever since.

Ta for the update, another place to check in case of trouble