Discharging voltage & electrical short?

[hodders]

Over the last couple of days I've noticed the voltmeter in the red at just over 10V, normally a healthy 12.
Today while driving into work on the motorway, the radio suddenly cut out, voltmeter dropped to almost zero, also the rev counter went dead & no indicator lights on the dashboard. Indicators OK I think, but dim. Horn also not working properly. The rev counter did pick up again, but now rather erratic. Other stuff OK - headlights, fan, aircon, windows.

I assume a short has occurred somewhere, maybe blown a fuse or two. Any suggestions for a likely place to start the detective work?

two other clues - I did wonder if the purge pump has not been switching off in this hot weather, maybe discharging the battery more than usual? More likely - I used a garage jet wash a few days ago. But I avoid dousing the engine bay and there are normally with no ill-effects.

[Lotus-e-Clan]

This does sound like water ingress given the recent pressure wash.

I'd have a good look at the fuse and relay boxes under dash (take each fuse/relay out).

For example, water could have got in via the grommeted cable holes (eg bonnet release cable?) in the top right (drivers) bulkhead and dripped over the fuse/relay boxes.

My bulkhead cable grommets have been sealed with additional rubber compound (previous owner must have had this done for a reason).

[hodders]

Update - symptoms continued in the drive home, except the rev counter died completely as did the voltmeter. With 10 miles to go, she "failed to proceed" as someone recently described their breakdown. Apparently lost all electrics, in fact the battery was down to 9v. The AA man diagnosed a failed alternator. So I will attempt to locate & fit one of these.

[hodders]

Wire from the alternator to the starter motor solenoid had snapped off at the alternator terminal... replacement supplied & fitted by Mike T in the time it took to drink a cup of coffee...