Tail Lights Not Working :(
01-12-2013, 06:19 PM
#1
Race Director
Thread Starter
Tail Lights Not Working :(
Since my 2nd body off on my '69 I haven't been able to get my tail lights working again.
-Doesn't look like any fuse is blown.
-Nothing in the rear works(tail lights, side blinkers...)
-Front lights work fine.
Turn signals don't flash, just on(front) or nothing(rear)
I think this is also connected to my LS1 swap electrical problems. Any time a light/brake/blinker(all get power from orange wires) everything electrical primes with the LS1(fuel pump, injectors, maf? ...)
Pretty sure it's a backfeed of power through grounds but I've got plenty of grounds from what I can tell.
-Doesn't look like any fuse is blown.
-Nothing in the rear works(tail lights, side blinkers...)
-Front lights work fine.
Turn signals don't flash, just on(front) or nothing(rear)
I think this is also connected to my LS1 swap electrical problems. Any time a light/brake/blinker(all get power from orange wires) everything electrical primes with the LS1(fuel pump, injectors, maf? ...)
Pretty sure it's a backfeed of power through grounds but I've got plenty of grounds from what I can tell.
Last edited by PUNISHER VETTE; 01-12-2013 at 06:21 PM.
01-12-2013, 09:48 PM
#2
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St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
This really should help you understand how the lamps work.. and help you solve the problem. I hope.
Most people don't realize the stop lamps go through the turn signal switch and/or how it works. The lamps are fed power on two wires.. One is the (both lamp) power and one wire is the turn only power. So in a nut shell... When you hit your brake lamps the power form the switch goes to the turn signal switch (not the rear). If you have the turn signal switch in the neutral position then power goes out to both lamps (green and yellow below). But if you have a turn signal on.. the power from the white wire is cut and switched to purple power wire (which has the flasher) for the side you are turning on.
So with this in mind.. you should start some diagnosis...
1) Always verify you have power coming out of the brake lamp switch or white wire.
2) Verify power on the purple wire at the flasher.
3) Place a jumper in line for the brake lamp switch (testing takes time) and disconnect your distributor power wire (save those points).
4) Once you have the power jumped at the switch then go to the turn signal switch and see if you have power at H and E in the diagram below.
5) If you have power at H and E without the turn signals on you should have power coming out on G and F below. If not then take a hard look at the connection for the t/s switch..
6) Test the flash.. turn the lever to one side or the other and test to see if power is pulsing on either F or G depending on side.
If all this works.. then I would go to the back of the car and start working forward by testing the grounds at the taillamps and pinging the wires. The rear harness connector can sometimes be the culprit too.
Hope this helps you Punisher.. if you need more post back.. signing off for the night though..
Willcox
Most people don't realize the stop lamps go through the turn signal switch and/or how it works. The lamps are fed power on two wires.. One is the (both lamp) power and one wire is the turn only power. So in a nut shell... When you hit your brake lamps the power form the switch goes to the turn signal switch (not the rear). If you have the turn signal switch in the neutral position then power goes out to both lamps (green and yellow below). But if you have a turn signal on.. the power from the white wire is cut and switched to purple power wire (which has the flasher) for the side you are turning on.
So with this in mind.. you should start some diagnosis...
1) Always verify you have power coming out of the brake lamp switch or white wire.
2) Verify power on the purple wire at the flasher.
3) Place a jumper in line for the brake lamp switch (testing takes time) and disconnect your distributor power wire (save those points).
4) Once you have the power jumped at the switch then go to the turn signal switch and see if you have power at H and E in the diagram below.
5) If you have power at H and E without the turn signals on you should have power coming out on G and F below. If not then take a hard look at the connection for the t/s switch..
6) Test the flash.. turn the lever to one side or the other and test to see if power is pulsing on either F or G depending on side.
If all this works.. then I would go to the back of the car and start working forward by testing the grounds at the taillamps and pinging the wires. The rear harness connector can sometimes be the culprit too.
Hope this helps you Punisher.. if you need more post back.. signing off for the night though..
Willcox
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drvaclassic (10-26-2023)
01-12-2013, 10:48 PM
#3
Race Director
Thread Starter
Thanks. I'll try to dive into this hard tomorrow.
My center console isn't in... could that be causing issues with anything?
I only ask because really I never touched any wiring related to the rear lighting. So I find it strange they're not working anymore.
No distributor anymore with the LS1 so not sure about the bypassing step #3.
My center console isn't in... could that be causing issues with anything?
I only ask because really I never touched any wiring related to the rear lighting. So I find it strange they're not working anymore.
No distributor anymore with the LS1 so not sure about the bypassing step #3.
01-13-2013, 11:25 AM
#4
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St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Thanks. I'll try to dive into this hard tomorrow.
My center console isn't in... could that be causing issues with anything?
I only ask because really I never touched any wiring related to the rear lighting. So I find it strange they're not working anymore.
No distributor anymore with the LS1 so not sure about the bypassing step #3.
My center console isn't in... could that be causing issues with anything?
I only ask because really I never touched any wiring related to the rear lighting. So I find it strange they're not working anymore.
No distributor anymore with the LS1 so not sure about the bypassing step #3.
You'll still need the jumper between the two wires at the brake lamp switch in three..
LS1 huh.. I hate points too.. LOL..
01-13-2013, 11:41 AM
#5
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Replace it anyway. I've seen fuses which looked good until you pulled them out into the light of day and could see the burn.
Check the rear harness ground on the frame. Good contact is required.
Ensure the rear harness is plugged in well to the main dash harness.
...Nothing in the rear works...
Ensure the rear harness is plugged in well to the main dash harness.
01-13-2013, 12:15 PM
#6
Race Director
Thread Starter
The fuses are my first thing to check this morning. Taking each one out to inspect. Wouldn't know which one to replace... DIR SIG, Tail lights, stop....
01-13-2013, 12:32 PM
#7
This a quick brake light circuit check I use to check operation of the brake light circuit.
1. Turn on the hazard lights, they will flash the indicators on the dash.
2. Depress the brake, the flashing will stop, but the indicators will remain on, with no flash.
If this works the problem is down stream from the switch.
The brake switch circuit overrides the T/S & Hazard circuits.
1. Turn on the hazard lights, they will flash the indicators on the dash.
2. Depress the brake, the flashing will stop, but the indicators will remain on, with no flash.
If this works the problem is down stream from the switch.
The brake switch circuit overrides the T/S & Hazard circuits.
Last edited by bpassmore; 01-13-2013 at 12:35 PM.
01-13-2013, 12:34 PM
#8
Race Director
Thread Starter
The shift console should not play an issue. Make sure the connector at the bottom of the column is not loose too.. that would cause you all kinds of issues.
You'll still need the jumper between the two wires at the brake lamp switch in three..
LS1 huh.. I hate points too.. LOL..
You'll still need the jumper between the two wires at the brake lamp switch in three..
LS1 huh.. I hate points too.. LOL..
Trying to get all your info straight from your first post. I need to bridge the white wire from the brake switch and the purple wire right before the flasher? Or is it saying to bypass the brake lamp switch altogether and give direct power to the white wire?
01-13-2013, 12:42 PM
#9
Race Director
Thread Starter
This a quick brake light circuit check I use to check operation of the brake light circuit.
1. Turn on the hazard lights, they will flash the indicators on the dash.
2. Depress the brake, the flashing will stop, but the indicators will remain on, with no flash.
If this works the problem is down stream from the switch.
The brake switch circuit overrides the T/S & Hazard circuits.
1. Turn on the hazard lights, they will flash the indicators on the dash.
2. Depress the brake, the flashing will stop, but the indicators will remain on, with no flash.
If this works the problem is down stream from the switch.
The brake switch circuit overrides the T/S & Hazard circuits.
So what's down stream that I can check seeing that my brake switch is working.
01-13-2013, 02:11 PM
#10
Start at your rear lights and work toward the switch,checking connectors and double check the grounds at the rear.
Is the lights the only things not working in the rear? Is there anything any where else not working?
Is the lights the only things not working in the rear? Is there anything any where else not working?
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spdrcr29 (08-17-2019)
01-13-2013, 03:03 PM
#11
Race Director
Thread Starter
Fixed!!
Well. Figured it all out!
After the LS1 swap I never hooked up the old fuel pump wire as I was using the F-body pump. Hooked up what looks like just a black ground wire to the pump and all the issues went away.
I thought that wire was power for the pump but now i remember the pump was on the motor and according to the wiring diagram it's just another ground I never had hooked up!
lesson learned!
weird how all those issues are caused by one tiny little wire.
01-13-2013, 05:05 PM
#12
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St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15
Good deal....
Just in case others see this later.. You jumper the brake lamp switch. This will put power on the white wire so you don't have to keep pushing the pedal.
In some cases you can start from the rear but when the customer states there is a turn signal issue more times than not it's something in that area instead of in the rear. When turn signal pups out I go to the source and work backwards.
IMHO,
Willcox
Just in case others see this later.. You jumper the brake lamp switch. This will put power on the white wire so you don't have to keep pushing the pedal.
In some cases you can start from the rear but when the customer states there is a turn signal issue more times than not it's something in that area instead of in the rear. When turn signal pups out I go to the source and work backwards.
IMHO,
Willcox
07-12-2018, 09:14 AM
#13
Cruising
Possible fix for C3 tail lights not working
Even though I’m replying 4-years after the last thread posting, I wanted to relay what I had found on my 1978 C3. When I purchased the car everything was correct, except the rear brake lights and turn signals did not function With the brake pedal nor did they work with the turn signals. The turn signals would merely come on and stay steady, but would not flash. The front turn signals and running lights would stay on steady but nothing on the rear brake lights/signals were working. I checked only the left rear brake light bulb filaments which looked perfectly intact. Figuring the right side bulb would look identical, and it was a problem elsewhere in the system, I checked all connections including the front to rear wiring harness, turn signal switch, brake light switch, etc. A friend of mine who knows Corvettes well told me he had the same issue and I should check BOTH my rear bulbs again. Once home, I pulled out the right rear brake bulb and found one of the two elements burned out. I replace that with an on-hand 1157 and it worked perfectly. I then went back to my left rear brake bulb, which I had previously checked and found both filament were intact, and using an ohmmeter, I found that one of the filaments was not completing the circuit even though the bulb looked new. In all, it was a $6.50 correction and it would’ve saved me a lot of time if I had Just checked BOTH rear tail lights. Long story short, if your rear brake lamps do not work, please begin with both rear tail lights to save yourself frustration, time and effort. I hope this helps someone who is having the same issue
08-15-2019, 11:49 AM
#14
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Another C3 rear lamp different side to side
I have a question 68 with same issue, tail lamp bright on left side, yet the voltage to each measuring the same at 11.9 volts. New lamp housings, grounds replaced, where is the differential in intensity coming from if the voltage is the same?
07-11-2020, 12:46 PM
#15
Thanks, Wilcox!
This really should help you understand how the lamps work.. and help you solve the problem. I hope.
Most people don't realize the stop lamps go through the turn signal switch and/or how it works. The lamps are fed power on two wires.. One is the (both lamp) power and one wire is the turn only power. So in a nut shell... When you hit your brake lamps the power form the switch goes to the turn signal switch (not the rear). If you have the turn signal switch in the neutral position then power goes out to both lamps (green and yellow below). But if you have a turn signal on.. the power from the white wire is cut and switched to purple power wire (which has the flasher) for the side you are turning on.
So with this in mind.. you should start some diagnosis...
1) Always verify you have power coming out of the brake lamp switch or white wire.
2) Verify power on the purple wire at the flasher.
3) Place a jumper in line for the brake lamp switch (testing takes time) and disconnect your distributor power wire (save those points).
4) Once you have the power jumped at the switch then go to the turn signal switch and see if you have power at H and E in the diagram below.
5) If you have power at H and E without the turn signals on you should have power coming out on G and F below. If not then take a hard look at the connection for the t/s switch..
6) Test the flash.. turn the lever to one side or the other and test to see if power is pulsing on either F or G depending on side.
If all this works.. then I would go to the back of the car and start working forward by testing the grounds at the taillamps and pinging the wires. The rear harness connector can sometimes be the culprit too.
Hope this helps you Punisher.. if you need more post back.. signing off for the night though..
Willcox
Most people don't realize the stop lamps go through the turn signal switch and/or how it works. The lamps are fed power on two wires.. One is the (both lamp) power and one wire is the turn only power. So in a nut shell... When you hit your brake lamps the power form the switch goes to the turn signal switch (not the rear). If you have the turn signal switch in the neutral position then power goes out to both lamps (green and yellow below). But if you have a turn signal on.. the power from the white wire is cut and switched to purple power wire (which has the flasher) for the side you are turning on.
So with this in mind.. you should start some diagnosis...
1) Always verify you have power coming out of the brake lamp switch or white wire.
2) Verify power on the purple wire at the flasher.
3) Place a jumper in line for the brake lamp switch (testing takes time) and disconnect your distributor power wire (save those points).
4) Once you have the power jumped at the switch then go to the turn signal switch and see if you have power at H and E in the diagram below.
5) If you have power at H and E without the turn signals on you should have power coming out on G and F below. If not then take a hard look at the connection for the t/s switch..
6) Test the flash.. turn the lever to one side or the other and test to see if power is pulsing on either F or G depending on side.
If all this works.. then I would go to the back of the car and start working forward by testing the grounds at the taillamps and pinging the wires. The rear harness connector can sometimes be the culprit too.
Hope this helps you Punisher.. if you need more post back.. signing off for the night though..
Willcox
Aldo Jackson '69 Coupe
05-26-2021, 10:24 PM
#16
Le Mans Master
This a quick brake light circuit check I use to check operation of the brake light circuit.
1. Turn on the hazard lights, they will flash the indicators on the dash.
2. Depress the brake, the flashing will stop, but the indicators will remain on, with no flash.
If this works the problem is down stream from the switch.
The brake switch circuit overrides the T/S & Hazard circuits.
1. Turn on the hazard lights, they will flash the indicators on the dash.
2. Depress the brake, the flashing will stop, but the indicators will remain on, with no flash.
If this works the problem is down stream from the switch.
The brake switch circuit overrides the T/S & Hazard circuits.
So i'm now having the same issue, NO BRAKE LIGHTS every other light, & signal work perfectly. when i put on my hazards, they both flash in the rear & on my dash both green arrows as well, I hit the brakes & nothing changes.
Dash still flashes left & right green arrows & the rear light both sides still flash. Hitting the brakes does nothing ! I'm next going to check the bulbs, thats easiest & cheapest. I may also have a ground issue because in the past some lights were brighter then others & other flashed faster or slower then others. Where is the main rear connector all are talking about ?
05-29-2021, 01:06 PM
#19
Le Mans Master
05-29-2021, 01:35 PM
#20
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You need to start a clear new thread then, that shows you followed the steps Willcox have provided - and what were the results of those steps you took.
If you have not done the diagnosis - which it seems may be the case...no one here is going to be able to do that for you unless they are on the same street as you...
Those steps (in the write up) are golden and have solved the issues each time I've been down this road with a C3 and I am sure 100s more...
If you have not done the diagnosis - which it seems may be the case...no one here is going to be able to do that for you unless they are on the same street as you...
Those steps (in the write up) are golden and have solved the issues each time I've been down this road with a C3 and I am sure 100s more...