Outer Limits 4x4 Board

I have a GQ TD42 patrol thats playing up.
Put your foot on the brake and the glow plug light, high beam light come on, blinkers flash quiker and it idles up.
Battery is a few years old, reads 12.6 and 13.4? when the car is running.
I have checked the main earth that runs from the battery to the battery tray then to the donk. Cleaned them and sprayed with battery terminal stuff.
Nothing electical has been done to it in the past few months and was working fine till the other day.

Could the battery be failing and still reading OK?

It's more likely to be a bad earth near your brake lights. Are your brake lights actually working? Tail lights? Reversing lights?

Bingo

Spoke too soon. Its back again

-Scott- wrote:It's more likely to be a bad earth near your brake lights. Are your brake lights actually working? Tail lights? Reversing lights?

Brake lights work but when the parkers are on they are at brake light brightness........Reverse lights work, blinkers work.
Thing thats making it hard is ,its random. Thought I had it nailed but came back right at the rego check