Rep Power: 0

My 2001 Honda Civic is a sad boy currently, and probably not economical to get a mechanic to repair. Fortunately I know quite a lot about 12V electrics. Unfortunately I know almost nothing about cars.

2001 Honda Civic, 50k miles (bought 8 months ago at 42k miles)

Typically, car has no power. Immobilizer doesn't work & no lights on dash. Sometimes immobilizer works, when turning key to on position, dash lights will light up for 0.1 seconds, then all lights turn off and immobilizer has no power. Very occasionally, car is able to start. Battery voltage reads okay.
Previously, car wouldn't start. After jump start, car lost power whilst driving. Slave battery got us home.

Things I've tried:
Have since replaced car battery with new, car worked for about a week, maybe 50 miles across 5 drives, but yesterday wouldn't start, exactly the same as before new battery.
Have tried spare car key, same issues.


My knowledge of batteries would say to be that with a good voltage reading, we'd expect the battery to be sufficiently charged. Is it possible I'm wrong & the battery has next to no charge, isn't re-charging, but can still have good voltage?

Appreciate any assistance or thoughts or diagnostic ideas people have. Also if anyone has the wiring diagram for this vehicle I'd be very greatful! It's the UK version, automatic. I think it's the EX version? It has sunroof, ABS, Electric windows & door locks.

 
Rep Power: 0

This is (hopefully) solved.

The car has a battery cut-out & whilst I'd noticed that, I hadn't noticed that it was a bit loosly connected to its wire. Lots of spit & cleaning later, including where I think it had been arcing a little, plus putting it all back together as tight as possible, I am moving again.

Here's hoping it doesn't come loose on the road (again!)