One for the electrical savvy.

[Steve Anderson]

Hi all,

Today I had a Gremlin creep into my brake lights. 4.4 volts seeping in from an unknow feed and lighting up the brake light side of my lights.
I disconnected the lights (LED), the tow plug loom and disconnected the rear loom from under the passenger side of the car. From my limitted knowledge that should have isolated the rear loom. The 4.4 volts are still there.
The last thing running off of the loom is the sub tank. I cannot see any other feeds anywhere. Am I missing something?
Also, the lights and brake lights work fine. Just the dull LEDs are the give away. Curiously, the lights will not elluminate with the brake light fuse removed, though the 4.4 volts are still present.
I am at a loss as to what bought this on.

Any ideas?

It is a 2003 Patrol Wagon, if that helps. 3.0ltr TD

[4bye4]

G'day and welcome to the forum. A nice easy one for starters. NOT. Probably an earth gone high resistance or gone altogether and something is seeking earth via the brake lights. Yendor or ET may have some better ideas than me. You might like to post an introduction as well Steve.

[the evil twin]

What mods/work/equipment have you touched recently?
Any extra power sockets down the back?
Do you have a Trailer Brake controller?
Do you have Cruise Control?
Do the LEDs still glow with key removed or only from ACC/On?
How long ago did you fit the LEDs
Is it an Auto or Manual?

It could be lots of things even leakage thru the brake switch.
On rare occasions I have had to put load resistors across the brake lamp circuit in the past to pull down the floating voltage on the low side of the Brake switch after a full LED conversion

[mudnut]

Hello and welcome to the forum, slip over to the introductions and tell us a bit about yourself and your patrol. Sometimes earthing can cause problems as the body sits clear of the chassis on rubber mounts. I have added an earth to the rear of the vehicle and all of my weird electrical probs ceased to exist. Hope it works for you. Edit, I was beaten to the punch.

[Steve Anderson]

Touched nothing at all. Just noticed the LEDs on slightly.
# sockets down the back. Been there for over a year.
Yes, it has a tralor brake controller. I unplugged that and the loom and still the power bleed was there. But I will look again at the controller as light was fading and I may have missed something.
Yes, I have cruise control. Stock issue with the car.
LEDs are onn throught the brake light sytem which is battery fed, so yes, the lights are on all of the time. Off with the brake light fuse removed.
LEDs have been on for 3 years but as said in my post, I unplugged the lights, so the issue is not there.

The 4.4 vots is not coming from the brake switch, It is somehow there in the loom but the fuse seems to complete the circuit somehow..

I am at a loss.

I tend to also think it is an earth isse 4bye4.
just about to go out for round two.

I will put a link in the new members area so you can all see what I get up to.

Thank you for the help thus far also.

[the evil twin]

LEDs are onn throught the brake light sytem which is battery fed, so yes, the lights are on all of the time. Off with the brake light fuse removed.
LEDs have been on for 3 years but as said in my post, I unplugged the lights, so the issue is not there.

The 4.4 vots is not coming from the brake switch, It is somehow there in the loom but the fuse seems to complete the circuit somehow..



I know the brake lights are hot off the battery, that Q was to try and help eliminate other Accessories
Your symptoms are indicative of a dodgy brake light switch 9 out of 10 times but if you have eliminated that then fair enough.

Is your high mounted Brake Light LED or Incandescent?

[Yendor]

How old is the battery in your multimeter? What is the reading across the vehicle's battery?

Have you just installed a new head unit or reversing camera?

ET has already covered the main causes. Double check that you did fully disconnect the electric trailer brake unit.

Extra load in the stop light circuit will more then likely stop the dull LEDs, I.E having a standard incandescent bulb fitted in the high mount.

Does your cruise control still work?

[Steve Anderson]

I have not givien any thought to the high brake light.

I will look into that asap.

Cheers.

[Steve Anderson]

Yes. I put a new head unit in, making the old units reversing camera obsolete.
Nothing is wired into the brake light relay though and I put the head unit in just before xmas. All was good then.

I will look at the switch more closely and replace it.

Thank you for all of your ideas.
Though I am still perplexed as to why there is still power in the loom with it disconnected from the car.

[Yendor]

Well it seems like you have all the answers.......good luck with it.

[Steve Anderson]

No answers..

Replaced the brake switch and still the same.
Closer to the prblem perhaps as the lights were on whilst the plug was not connected. So the issue might will be in the loom just before the fuse.
I will look again on Monday.

[garett]

have seen this problem once in a different car. crushed wire. run a new wire problems gone. just a thought.

[the evil twin]

No answers..

Replaced the brake switch and still the same.
Closer to the prblem perhaps as the lights were on whilst the plug was not connected. So the issue might will be in the loom just before the fuse.
I will look again on Monday.

NOT SURE i FOLLOW... If the fault is in the loom just before the fuse how can the power get past the "normally open circuit" brake switch?

Is your hi mount brake lamp LED or Incandescent?

[Yendor]

No answers..
\

That doesn't surprise me.

You need to take it to an auto electrician as you have NFI and your not prepared to take on advise.

It will work out cheaper for you to take the vehicle to someone....