Intermittant Prado 150 electrical fault

[brett004 Junior Member Find all posts View Profile Close brett004]

POST UPDATE:

Just an update to this post, I disconnected all the engine earths including battery and cleaned and replaced and the fault to this day has not reoccured.

Hi all, has anyone had this type of random electrical fault before,
2010 Prado 150 1KD Auto, 170,000ks. Fitted with duel lead acid batteries and Redarc BCDC 1240D and 120w solar panel. Redarc wired with signal blue/orange/green trigger wires not connected.
Over the last 3 months this random fault has only happened 4 times.
Driving along then suddenly the Android head unit will start re-booting (due to the unstable voltage levels) and the digital volt meter that I have installed in the car I can see the voltage levels rapidly changing, down to 10v upto 15.8v all over the place. This happens and next the car dash goes blank and the engine stops. Pull over put the trans into park, foot on brake and start the car as normal and all good for another week or so. I thought it may be a faulty regulator in the altinator but I am not so sure as it is so random. Battery voltage at rest = 12.3v (12 month old Yuasa) Engine running = 13.9v no load, 13.6v full load. I have started checking all connections, earths etc.

Any suggestions or ideas. Thanks in advance.

[RPP Senior Member Find all posts View Profile Close RPP]

Some suggestions:

Sounds like something is interrupting the cranking battery voltage/earth randomly.
Assuming you haven't been driving thru deep water/mud (that might impact the alternator):

1. check the cranking battery terminals, and major fuses, for good connections, and the chassis earth
2. check the wiring to all high power accessories for abrasion/shorts etc - winch, the BCDC, compressor etc

[ptommo59 Senior Member Find all posts View Profile Close ptommo59]

Most probable cause is a loose/dirty body earth connection from your battery to the mudguard which is making it intermittent, initially causing a voltage drop across that point (your 10V), the ECU will try to compensate by increasing the alternator output voltage but when the connection remakes it will be at maximum output (your 15.8V) and have to readjust back down.

Try removing the earth lead bolt in the guard and at the battery then clean the connections and retightening and see if that helps.

[brett004 Junior Member Find all posts View Profile Close brett004]

Thants guys, it confirms the path that I was on, today before reading your replys I had started to disconnect and clean all earths etc. I will complete and report back. Thanks for your time.