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. 

[Dave69x33]

DaveK,

Yes, tried different flasher units to verify the one in the car was okay. No change to the issue.

Camaronut, 

It may come to that.  This evening I’ll confirm if it’s the tail or stop lights that are on.  If I pull a bulb socket and one filament in the bulb is on, that’s the tail light but if both filaments are on, that would be the brake lights, correct?

I also plan to swap and test the light and ignition switches one at a time to see if one got damaged. Both switches have battery power sent to them 100% of the time, correct?

If one of those two switches got damage with a bent spade pin or loose wire, I am assuming one of these switches could be the power source turning on the tail lights. Or is this a wrong assumption?

[camaronut]

I would defiantly check the wiring to the headlamp switch. - Now make sure you have that switch grounded correctly. There's a wire connected to that plate that goes in front of the headlamp switch - check that to make sure its grounded.  Dangit - I should have told you that in the first place.

[Dave69x33]

Camaronut…not worries! I really appreciate your input!!

When I pulled the headlight switch to work on the RS vacuum hoses, I did check that the ground strap was still in good shape. The ground strap may not be making tight contact with the face of the headlight switch when the special nut is is tightened to hold the switch in place.

[camaronut]

Maybe pull the headlamp switch back out - and make sure you have that connector in correctly.  - Make sure that the front of the headlamp switch is clean and the ground plate.  Also - make sure the nut is tight when you button it all up.  Check for anything that may be burnt.

[Dave69x33]

Will do.  Thanks again for all the input!

I’ll report back with what I find. Maybe it will help someone else in the future…bc this issue is very unusual.

Once I find the issue, I’ll listen to your other bit of advice…”leave well enough alone.” LoL!

[David K]

Now that there is more information,  I would pull the headlamp switch back out and then verify re-install is good.
Are the dash or courtesy lights on as well?
Marker lights in the front or nothing but the rear?

[MyRed67]

You mentioned that you removed the wiper motor.   I believe the wipers and the tail-lights run through the same fuse.   So I would start there.   My wipers recently stopped working.   During trouble-shooting I found I had power to all 5 terminals on the wiper motor as long as the key was in either on position.  I found out it was a ground problem at the switch.  It also could possibility of ground problem at light switch.

[Rick68]

Do the rear side marker lights come on when the taillights come on? I would think that they would be spliced together with the taillights. I think it's the brake lights that are coming on. If you disconnected the turn signal switch and the problem went away I would check the brake lights. The taillights don't go through the turn signal switch. You did have the  brake booster out so maybe the brake switch got out of adjustment when you reassembled it. Disconnect the brake switch and see if the rear lights come on

[Dave69x33]

Thanks for everyone's help! Problem solved! It was the brake light switch.

I double checked to verify it was the brake lights that were on. My bad early on thinking it was the taillights.  I changed the brake light switch, and it solved the problem.

I took the faulty brake light switch apart to evaluate the reason it failed. The switch is very simple with contact points separated by the spring-loaded plunger when the brake pedal is released. The points make contact when brake pedal is pressed, and the plunger extends out of the housing.  It’s still not clear why the switch failed. I do not see any internal damage to the switch.   The switch was a NAPA Echlin #SL169. I typically get good reliability from Echlin electrical parts. However, I had replaced the switch back in March 2022, so it did not have much usage between then and this new switch.

The switch looks like it was designed to have (2) sets of contacts 180 degrees apart. No broken contacts fell out of the switch when I took it apart.  Something in the switch failed to allow it to make electrical contact 100% of the time regardless of the position of the brake pedal.

Over the years I have had brake light switches fail where the brake lights would NOT turn on because the switch plunger stuck and would not extend when the pedal was pressed.  This issue was the opposite and the first time where the brake lights remained on regardless of the brake pedal position and the On or Off position of the headlight switch.  S I struggled troubleshooting this issue.

I can now rest again at night…lol.
Here are general pics of the switch.
Dave

[Dave69x33]

Here are views of the switch contact points in the open and closed positions.

[169INDY]

Wonder "IF" the Delco equivalent would be of any better quality and available.

[camaronut]

Awesome!!!!!  But nothing is as good as NOS GM parts.  I’d use this as a temporary fix and find the real deal.  Just my 2 cents.  I’ve found that AMC used lots of GM parts and marked them as AMC.  I’ve found a few parts like that and paid 1/4 the price….. but don’t tell anyone.  Lol