Converting Precedent Headlight Harness to Auxillary Battery

[Culln5]

Hey Guys,
I'm in the process of installing an auxillary battery and fuse block to run my accessories and need a little help with the headlights/tail lights. My 07 Precedent came with the lights prewired with a harness. Can anyone tell me which wires I nees to remove from the harness to power the lights? There were 2 yellows at the switch (power & lights). I would like to save the harness if possible so that if in the future I want to add turn signals and/brake lights.

Thanks,
George

[SaltLifeCC]

Are your lights currently powered by the blue wire coming off the 4th battery (passenger side front battery) and that blue wire is feeding down under the center cover under the tow switch? If so, you can just remove that feed and replace it with a feed from your battery and not have to change anything behind the dash. I did this but it was a couple of years ago and I don't remember the specifics. Seems like there was the blue wire connection and something about a yellow wire with a bullet connector on it. However, I believe forum user TahoeDawgZ71 is the one that helped me with the specific wiring in the battery bay from my 12v battery. I already had my stereo and lights wired up behind the dash and I didn't have to change any of that.

[Culln5]

Originally Posted by SaltLifeCC

Are your lights currently powered by the blue wire coming off the 4th battery (passenger side front battery) and that blue wire is feeding down under the center cover under the tow switch? If so, you can just remove that feed and replace it with a feed from your battery and not have to change anything behind the dash. I did this but it was a couple of years ago and I don't remember the specifics. Seems like there was the blue wire connection and something about a yellow wire with a bullet connector on it. However, I believe forum user TahoeDawgZ71 is the one that helped me with the specific wiring in the battery bay from my 12v battery. I already had my stereo and lights wired up behind the dash and I didn't have to change any of that.

Yes, the lights come off the blue wire from battery #4. Is it really that simple, by powering that wire from my new auxillary battery? What about the ground? Doesn't it have to come off the same battery (auxillary)? If so, where is the ground that feeds the lights?

George

[rinman]

You DO have to ground off of your aux battery. I did this about a year or so ago and don't remember exact wires. I did all the work behind the dash. I had to play around with the multi-meter to figure out which wire I need to ground to my aux battery, but it didn't take too long.

I have to work today, but when I get home tonight I will take a look if you haven't figured it out yet.

[SaltLifeCC]

Yes you have to ground it as well but the ground wire can run from the battery to the wiring under the tow switch cover as well. I think this may be where the yellow wire with the bullet connector came in. Of course, you can also run the wiring straight to behind the dash and just tap it from there but make sure everything is fused. The reason I did it the way I did was because, A - I could, and B - I already had everything wired behind the dash and my extra battery is mounted in the bagwell. So it was easier just to run the wires from the battery to the battery bay and just change the source and ground for the 12v aux power to the dash.

[Culln5]

Well it was that simple. I disconected the blue wire and ran power from the fuse block back to the blue wire, then jumped the ground from the auxillary battery to the ground on the light harness. I figured teh "double negative" (1 from the auxillary battery and one from the pack batteries) wouldn't hurt anything.

I mounted the auxillary battery and the fuse block behind the dash. The fuse block now powers the head/tail lights, LED lights under the body, the radio, and a cigarette lighter. I took the ring terminals off my 1.5 amp charger and replaced them with a cigarette lighter plug so I can just reverse charge the auxillary battery.

Everything behind the dash is secure and in wire loom. The job looks really nice for something that will never be seen. LOL..... and, of course, I forgot to take a picture before I buttoned it up.

George

[Tennshooter]

Can you post pics of what this all looks like??

[Quizzy]

Can you clarify which wire on the light harness was the ground?

Originally Posted by Quizzy

Can you clarify which wire on the light harness was the ground?

Originally Posted by Quizzy

If I do go with the aux battery setup, how do you tie that in to the stock harness for the lights?

yes it can hook into the stock harness

black to ground and red to positive

What battery would you recommend?

a deep cycle 12v battery

Where do I put the battery?
there are meany places to put it .. search forum there are tons of ideas

Does it charge with the main pack?
no .. you need a 12v charger

Originally Posted by crash test dummy

it will require you to hook up "blue" wire to the 12v + of the battery .. if you watch video you will see the "blue" wire in the center cluster (min 8:20 of video) hook that to 12v battery

then you need to find the ground (black wire)in the wiring harness and hook it to the 12v- post

,,,