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No parking lights. All others work.

951 Views 29 Replies 6 Participants Last post by  jamescarter61799
Hi guys.

I Already searched the forums and YouTube and everyone mentions fuses relays and some mention the headlamp switch.

None of my parking lamps work. All other exterior lighting is fine. Turn signals, brake lights, hazards etc.

Vehicle is 2006 TB 4.2 with the automatic DRL

I cannot find reliable schematic or pin out diagram of the headlamp switch or BCM.

Ideally I would like to trace the voltage and see if it's possiblity a break in circuit or I can test pins on the body control module.

Since it has Daytime running lights could it be a photo eye?
Looking for suggestions on where to start. Where are the other components that control the lighting circuit?
Trying to get the lights working because right now my wife can't drive at night.

I have checked all fuses and relays and have verified operation.
I do not believe my headlamp selection switch is bad, I installed a new one from rock auto and that didn't fix my issue.
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JAMES --- break your monoparagraph down to single sentences forming individual paragraphs.

It's just good form to help us read about your problem.


Got it?
Get it?
So, after dark, the low beam headlights do not function?
The low beams function at night.
So then why can't your wife drive the car at night if the low beams are working?
So then why can't your wife drive the car at night if the low beams are working?
I'm a little perplexed too --- but let's try to figure it out better.

There are a lot of "things" that can affect the lights.

1. Multifunction switch (not likely here, but it's included)
2. Relays --- they may click but can they pass current?
Either swap them with a known good one or test them -​
there are relay testers available and for a fact -​
on my TB several of the ones that worked, tested BAD on my tester.​
3. I'd not be looking for 12 Volts; I'd be looking for bad grounds.
4. Use a $10 Logic Probe from Harbor Fright.
5. DO NOT puncture any wires unless you heal them up again!

Primary Rule here:
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She technically "can" drive the vehicle at night..
The problem is the running lights at the rear of the vehicle are inoperable.
Therefore, unless she has her turn signal activated or is on the brake pedal or in reverse there are no lights on the rear of her vehicle. The brake lights and running lights share a bulb on this vehicle.
You mentioned grounds.
Could you please elaborate on what exactly I am looking for (color of wire, continuity, etc) I do have a multimeter I can sniff around with.
Do you mean the tail lights are not functioning?

To me running lights mean something completely different than parking lights and parking lights are completely different than tail lights.

We need you to be specific in order to provide you with correct information. So, are you referring to the red tail lights that are illuminated when you turn the headlights on?
Yes sir, those specifically. The ones that are dimly lit in the rear while driving at night.
OK. Have you looked at the circuit board that the bulbs plug into? They are known to go bad and replacements sell for $15 - $20 each depending on brand at I would take a DMM and see if there is 12 VDC in the bulb side of the lamp socket when you turn the headlights on. If you do not see 12 VDC, then back probe the connector and you should see 12 VDC between pin A and pin E (ground). If you see 12 VDC at the connector, then replace the taillight circuit boards. If you do not see 12 VDC at the connector, then you have to look further up the chain so to speak.

I've attached the lighting system electrical diagrams for you to use.

Good Luck!


This ---->
"The problem is the running lights at the rear of the vehicle are inoperable. "

....................... changes things --- big time.

You've got to be concise with your symptoms --- now we have to go in an entirely different direction.

You likely have broken wires in the tailgate wire bellow at the hinge area or some bad circuits in the multipin connectors on the three-gang tail light nacelles.
Bicycle part Rim Automotive tire Auto part Automotive wheel system

Tell us truthfully --- are you having no marker or no tail lights?
These "markers" are different from the tail lights - and let's not talk about brake/turn lights --- OK?​
Tell us about the license plate illumination light too.​
THEN we have to talk about the CHMSL.

EDITED for spelling mistakes and the addition of one image.
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Sorry guys about not being specific. I'll post some pictures so there isn't any more confusion
Automotive parking light Automotive tail & brake light Automotive lighting Automotive tire Car

Car Vehicle Automotive tail & brake light Automotive lighting Automotive tire

Vehicle Motor vehicle Car Steering part Steering wheel


I will check the circuit board for the tail lamps with my DMM today.
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Just a schmall hint --- the left side appears to have a much higher failure rate than the right one.

This has been the situation on both a SoCal (no salted roads) vehicle and a GMC version that had been in Montana (very salty roads) all of it's known life.

Go figger .......................... but I've seen this a few more times too .... just sayin' .........

Look for rusted-away pins in the receptical end of the boards - since those pins are very small and hard to see for rust or broken off conditions.
I've been there, done it too!​
It had a new board that was pre-installed before I got the vehicle ----- and inside the female end, one of the old pins had broken off in the holder.

When the new board was installed, the old pin just shoved the new pin out of the plug end and even though it looked OK, it was not making contact.

No voltage to light blue wire before the circuit board with lights on. I do get 12 volts with brakes applied.

Also, the two lights that illuminate the license plate do not work as well.

Motor vehicle Hood Automotive tire Bumper Automotive exterior
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Tell me if you have RPO code T84 and T85?
Looking for suggestions on where to start. Where are the other components that control the lighting circuit?
You must start by checking these lines. Are you sure all fuses and relays are good?
Font Rectangle Slope Parallel Schematic
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Will do.
Is FW in-between C3 and C4 an abbreviation for a color?
Praying it's not the BCM, I know you have to get those flashed at the dealer, at least that's what I was told.
If you remember, the BCM is connected to the rear fuse box with a cable. See photos. C3 and C4 are connectors. I have not yet been able to find information on FW 1080 and A14

Audio equipment Gas Electrical wiring Gadget Bumper

Rear Fuse Block - C4

Font Parallel Rectangle Auto part Drawing
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