Evening, I've been chasing a problem on a Range Rover for quite some time, the battery warning light and engine light were coming on a few years ago. Engine light got sorted but the battery light was very intermittent.

It has had the dashboard loom pulled into the engine bay to repair some wiring that mice ate, there were at-least 4 yellow wires that were the same colour so I'm hoping incredibly badly they're not the cause.

I've now basically got it to the point of where the battery light only comes on the dashboard when the accelerator pedal has been put to the floor. According to scan tool live data the alternator goes from 14.2V prior, to 11.8V afterwards. It doesn't go back to normal if you drive calmly or idle in park. I havn't turned it off and back on again just in-case it doesn't want to start up again.

Its had A new battery and alternator - the alternator has been sent into a local auto-electrical shop for testing and they needed to get some special test procedure from the agent for the "weird internal computer" (I call lies), they've said the alternator is fine - $15 test. Lesson learned.

The battery when everything is connected up produces decent sized sparks every time. I'm unable to pinpoint the voltage drop location as I'm afraid of having to pull the dashboard apart on the suspicion of it being inside the dash board, then later finding out that's not the cause.

If I unplug the large connectors from the main fuse block, majority of the sparking goes away.

I'm determined to get to the bottom of this situation as the car is awesome to drive and the owner wants to put some upgrades on it once the car is running mint.

There is a current draw across the engine bay fuse box in a few of the circuits.



Hopefully someone has had the same issue previously.

Next is probably to get the engine ecu tested since reading online the voltage regulation control function is performed inside of it.

Tonight I got some new info, the car needed to be doing over the speed limit with the heater full blast and wipers going.

Eventually got the light to come on, had to disconnect the battery for 10mins then nurse it back home. Ive come to the conclusion that Parasitic current draw is affecting the car full throttle under heavy load as there is a 0.4amp current draw across majority of engine bay fuse box.

Unless anyone here has clever ideas?