Tail lights are always on - 1969 Camaro

[Dave69x33]

ISSUE: I have an unusual electrical issue with my tail lights that only recently happened; they are always on regardless if the headlight switch is on or off.  Once the battery is connected, the tails lights turn on. 

BACKGOUND:  I recently pulled everything off the firewall to repaint it. It had gotten scratches and scuffed over the past 23+ years since I restored the my '69 RS Z28 back in 1995 - 2000.  The firewall along with number of components were refreshed. This job included pulling the wiper motor, steering column, brake booster, separating the firewall fuse panel electrical connector from the engine harness connector and setting both aside.  When the car was put back together, it starts and runs fine. The headlights, all (4) turn signal lights, and side marker lights, and the rear backup lights all work normally.  However, the brake lights and 4-way flashers do not work along with the tails lights being on when the battery is connected as noted earlier. 

It appears there must be an issue with a harness connection, or the ignition switch, the backup light switch, or stop lamp switch on the steering column.  My fuses all appear to be fine.  Thus the tails lights must be getting power from an issue with a switch, wiring, or wiring harness connector without the headlight switch pulled to ON.  All these components has worked fine prior to this work.

One thing I did find odd is one of the rear backup light bulbs was blown. I changed it and it now works fine. I wonder if my battery negative terminal was not fully disconnected when I plugged in the harness connectors to the steering column switches? I have rotary knob style quick disconnect "kill" switch attached to my negative battery terminal.  Over the years there has been occasions when the under hood light would flicker if I did not fully disconnect the kill switch.  I had my battery tender connected to the battery during the time I was doing the work so perhaps that may have shorted a switch? 

I will check the brake light bulbs and test a new 4-way flasher, but this issue really has be baffled!

Your tips and recommendations will be greatly appreciated!

[David K]

Marker light or brake lights on?

[Dave69x33]

Brake lights.

[RAfbody]

Sounds like possibly the brake switch under the dash.  When you depress the brake pedal, the switch button comes out turning on the brake lights. It could be misaligned or not connected well. I had this issue in the recent past.

[David K]

Sit in the seat and pull the pedal back with your foot (or get on your knees). Lights go off, make sure the switch nut is tight. Lights stay on, push the plunger in with a flathead. Lights out- adjust the switch. Lights stay on, your switch is kaput. Verify with a DVOM.

[cook_dw]

Just want to set some items here.

You've mentioned tail light and brake light.

Tail lights come on when the headlight switch is activated.

Brake lights are run through as mentioned above.


Is it both or just the brake lights are staying on with car powered.  You also mentioned the headlight switch which doesn't tie into the brake light circuit.

[camaronut]

I'd check the main harness connection at the firewall - hopefully nothing was bent when you put it back together.  Ya never know.

[Dave69x33]

Thanks everyone for your responses so far!  It's much appreciated!!

Sorry for any confusion I may have created offering too much info in my background discussion. I just wanted to "set the stage" on the work I recently completed that may help point to the root cause for my taillights always being on.

To confirm, it is the taillights that come on as soon as power is connected to the battery regardless if the headlight switch is ON or OFF. The lights do not look that bright, so I assumed it is the taillights and not the brake lights.   I will double check this later today by disconnecting the turn signal switch on the steering column. Since the brake lights and 4-way flasher lights run thru this switch, if it's disconnected and the taillights still come on, it will confirm that the brake lights are not what are coming on. 

DaveK - Thanks for that input but I did test the function of break light switch.  Years ago I had a brake light switch plunger stick in the closed (retracted) position and did not make the connection to turn on the brake lights. 

Camaronut - My gut tells me the issue is in that bulkhead harness connection.  It possible that a spade pin got bent or damaged.  That connection is a real "pain in the rear" (to put in mildly) to reach let alone get a good look at!  It will take time but pulling the master brake cylinder loose from the brake booster, then removing the booster provides the most clearance to the bulkhead connector.

Oh joy...can't hardly wait...LOL!!

I'll let you know what I find out.

[David K]

Do the bake lights work correctly? If so, I would lean towards a defective headlight switch.

[Dave69x33]

No, the break lights do not turn on when the brake pedal is pressed.

Also, the 4-way flashers do not work.

[David K]

Is it safe to assume you have the correct bulbs in there and the sockets are properly grounded?

[GMAD_Van Nuys]

Did you reconnect the two ground straps that go from the valve covers to the firewall?

[Dave69x33]

Yes, same bulbs that have worked for years. Checked them and they are fine. All grounds including those between the valve covers and firewall are in place.

Last night I pulled the wiring harness connector off the firewall and the spade pins all look fine. None are bent or damaged. Reinstalled the connector and still have the problem with the tail lights coming on when the battery is connected. If I disconnect the turn signal wiring connector on the steering column, the tail lights do not come on. So battery power is somehow bypassing the headlight switch to the tail lights thru some connection.  Wonder if it’s a bad connection at the ignition switch or headlight switch?

[David K]

Have you tried removing the turn signal flasher and or Hazzard flasher?

[camaronut]

Interesting.....very interesting.  Being that everything worked before hand -  something else had to be moved - wire wise - for this to occur.  Your last resort is to get the AIM wiring diagram and get one long lead and start measuring out continuity from point to point (back to front) in that circuit.  Good luck to ya.....
This reminds me of an old saying - "don't try to fix 1st gen Camaros when all is well"  - believe me - I know.