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Ask Mike V. Your Own Question
Mike V.
Mike V., Auto Service Technician
Category: Jeep
Satisfied Customers: 23844
Experience:  25 years of experience, Certified Subaru Technician and Nissan factory trained.
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Brake light issue, Last service full, 05 liberty, Tested

Customer Question

Brake light issue
JA: Have you checked the brake fluid? How's the level and when was it last changed?
Customer: Last service full
JA: What is the model/year of your Jeep?
Customer: 05 liberty
JA: Are you fixing your Liberty yourself? What have you tried so far?
Customer: Tested power from brk switch and have power to rear
JA: Anything else you want the mechanic to know before I connect you?
Customer: No
Submitted: 1 month ago.
Category: Jeep
Expert:  Mike V. replied 1 month ago.

Thank you for your question!
My name is ***** ***** give me a moment to review your question and respond with the assistance you need!

Expert:  Mike V. replied 1 month ago.

Just to be clear here, you are saying you have power to the brake light sockets on the back?

Customer: replied 1 month ago.
i have power comming off the brake light switch harness, countinuty at the points on the switch. When pedel is pressed down i have power at the tan/wt wire in the rear both sides
Customer: replied 1 month ago.
If im not mistaken the turn singals and parking lights receive the same ground as the brake light?
Expert:  Mike V. replied 1 month ago.

Ok,

Thanks for that info. Please give me a moment to pull up the wiring diagram and see what I can do to help.

I assume you have replaced the bulbs already?

Expert:  Mike V. replied 1 month ago.

I am actually going to check that ground right now, please stand by.

Customer: replied 1 month ago.
Didnt replace the blubs but switch the brake light blub into the parking socket and it work. Also, jump the brake light blub with the tan/white wire and a ground and it work with the brake pushed in
Expert:  Mike V. replied 1 month ago.

Sorry, you lost me.

You have power at the white/tan wires out at the sockets but with a bulb in that socket you don't get brake lights?
However when you put it in the parking light socket you got brake lights when you step on the brake?

Customer: replied 1 month ago.
No, i have parking lights and turn singals, so i put the brake light into the parking light socket to see if the light was good or bad with it in the parking light socket it was good. It also has countiuty across the blub.
Expert:  Mike V. replied 1 month ago.

Gotcha, sorry.

Just tested the bulb, my brain is in the wiring still.

Does the high mount brake light work?

Customer: replied 1 month ago.
I also took the brake light and jumped it off the wt/tn wire that goes in the main harnness and a ground and with the brake pedel pushed in the brake light worked
Customer: replied 1 month ago.
No it doesnt but it has power in the wt/tn wire with brake pushed in.
Customer: replied 1 month ago.
Does the top brake light play any role in completing the circut? Looking at the wiring diagram it feeds of the wt/tn wite from brk switch but has a seperate ground correct??
Expert:  Mike V. replied 1 month ago.

Ok

They are all using the same grounding point G304 is the ground. However it would seem like if the parking lights and signals are working the ground should be good.

If you rig up something to connect the test light to on the power side, like a small piece of wire, you could then use the other end of the test light to check the ground. If it lights, then you know the ground is good. If not, then trace the ground and locate the break in it.

Customer: replied 1 month ago.
The ground going to the left and right side of the rear sockets is the blk/white wire??
Expert:  Mike V. replied 1 month ago.

My diagram is showing solid black on the left and right, but black/white stripped on the high mount

But actually for the high mount it's G303 not 304 on the left hand drive model. Assuming you are in the US, this would mean it's a different grounding point, however possibly in the same harness.

Expert:  Mike V. replied 1 month ago.

And it also looks like it starts out solid red at the high mount socket and changes to bl/white

Customer: replied 1 month ago.
im testing from the rear right tail light assm. I back probed with wires out of the main harness with power supplied and brake pressed in. I connected the clip to the wt/tn wire and the probe point to the solid black wire and the test light shows good and reads around 12v
Customer: replied 1 month ago.
I also did the same with the blk/wht wire that runs in the asm and same thing happened
Expert:  Mike V. replied 1 month ago.

Ok

from what you are saying then, either the sockets themselves are no good or the bulbs. I do think that the bulb for the parking and turn signal should be a different bulb then the stop light, but still, you have all you should have when you are testing. Including a good ground source or the test light/meter wouldn't show any voltage with that test you just sent to me.

Customer: replied 1 month ago.
Are you talking about the socket that the blub itself is in or the socket that is part of the assembly. And what would make the whole light assm go bad
Customer: replied 1 month ago.
Are you still there
Expert:  Mike V. replied 1 month ago.

I am talking about the socket the light bulb goes into and I am sorry, I didn't get any notification that you replied to me.

Customer: replied 1 month ago.
Is possible that the whole circuit board for the light assm is bad. If it was the light/socket asm it would have worked when i jumped it with power/grnd
Customer: replied 1 month ago.
Wouldnt have worked or worked when i switched into the parking light slot
Customer: replied 1 month ago.
When looking at the circut board assm. Where the metal connections are in each light slot should all of them have countinuty across them
Expert:  Mike V. replied 1 month ago.

I don't have a blow up of the circuit board so I cannot answer the question about continuity for you

I guess what I am seeing here is you have power on the right wire, and you have ground on the right wire, so it should stand to reason that the bulb or the socket is the issue. Since the socket is part of the circuit board, then the board would have to be the problem in my opinion, you have everything you need to light a bulb.

This is the only thing that makes any sense to me on this to be honest.

Customer: replied 1 month ago.
That is what is what i came up with. I test the board sockets parking light has continuity, turn socket has continuity, but not continuity in the brake socket. Going to order and keep fingers crossed
Customer: replied 1 month ago.
But....just dont see how both could go bad
Expert:  Mike V. replied 1 month ago.

I am thinking one was went bad, don't notice, suddenly no brake lights and everyone notices!

I really think that's how it went down, they probably didn't go bad together, it just seems that way.

Please let me know what more I can do to assist you today. Also, please remember to rate my answer, Just Answer does not compensate me for my time and resources. Follow up questions are included in the price of your question. If you are using the free trial, or have a subscription a rating is still required.
Thank you so much!

Expert:  Mike V. replied 1 month ago.

Hadn't heard back and was wondering how you made out with this?

Expert:  Mike V. replied 1 month ago.

Do you need further assistance with this?
Did replacing the boards resolve the issue?