77 brake light help!

[jason ladd]

my reverse lights and turn signals are functioning properly, but i have no brake lights or running lights. i have checked my fuse and no issues there. i plan to purchase a multi-meter but don't have one on hand.
any thoughts as to where to start?

 

[John McVicker]

Your fuses may indeed be alright...but sometimes you can not tell by just ‘looking’.

Get the multimeter and test for continuity.

 

[Cromagnon]

Get a multimeter and learn how to use it. The interweb is your friend here. Also you need a vehicle specific wiring diagram, look in the FAQ for this. Next understand that your 40+ year old vehicle is inundated with corrosion, be ready to clean every electrical connection you find. Grounds are your friend, make sure your light fixtures are grounded with a properly terminated WB wire. If you rely on the Toyota supplied bolt, or hardware du jour, to the frame method you will be wasting a lot of time, yours and ours. The stop light and tail light are two separate circuits, therefore you will be looking for two different fuses. The fuses may be good but, referring to sentence #3, clean the fuse holder(s). 40+ years of corrosion is enough to wreak havoc on any electrical system. Always let us know what you find along the way. Oh and buy a star...that is what keeps the site alive.

 

[73FJ40]

Have you checked the bulbs?

 

[jason ladd]

Get a multimeter and learn how to use it. The interweb is your friend here. Also you need a vehicle specific wiring diagram, look in the FAQ for this. Next understand that your 40+ year old vehicle is inundated with corrosion, be ready to clean every electrical connection you find. Grounds are your friend, make sure your light fixtures are grounded with a properly terminated WB wire. If you rely on the Toyota supplied bolt, or hardware du jour, to the frame method you will be wasting a lot of time, yours and ours. The stop light and tail light are two separate circuits, therefore you will be looking for two different fuses. The fuses may be good but, referring to sentence #3, clean the fuse holder(s). 40+ years of corrosion is enough to wreak havoc on any electrical system. Always let us know what you find along the way. Oh and buy a star...that is what keeps the site alive.

thanks so much

 

[jason ladd]

Have you checked the bulbs?

i resolved one issue. i accidentally put a single prong bulb instead of an 1157 which did resolve the issue with the running lights. still working on the brake and hazard lights.

 

[Advrider639]

Answer to all electrical problems:

-use a multi meter
-check all of your grounds
-clean EVERY connector/pin

Edit:
-have a good wire diagram (thank @GA Architect for that one)
-don’t let any PO’s touch your harness

 

[GA Architect]

i resolved one issue. i accidentally put a single prong bulb instead of an 1157 which did resolve the issue with the running lights. still working on the brake and hazard lights.

These might help.

 

[Cromagnon]

Fantastic!! You solved one problem, now let's fix the other one. Print the two drawings that @GA Archetect was so kind to provide. You never mentioned hazard lights in the OP. You need to be accurate, consistent and concise when asking for help with electrical problems. What may not seem important, can be the nugget of information needed to solve the issue. So do the hazards work or not? The power for the hazard circuit is fed from the brake light circuit on a 77 from a GR wire. This is fed from the fuse panel. This circuit also feeds the horn, does the horn work? First thing to look at is the brake light fuse. Once you know that is good and you have cleaned the fuse holder contacts, go up the circuit from there looking for voltage. When cleaning contacts or working on pulling any electrical devices from the dash area DISCONNECT THE BATTERY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! When you fry something from inadvertently (or intentionally) shorting a connection you are going to hear a giant sucking sound coming from your wallet. You could burn the 40 to the ground and everything around it too, so be safe and smart.

 

[jason ladd]

Fantastic!! You solved one problem, now let's fix the other one. Print the two drawings that @GA Archetect was so kind to provide. You never mentioned hazard lights in the OP. You need to be accurate, consistent and concise when asking for help with electrical problems. What may not seem important, can be the nugget of information needed to solve the issue. So do the hazards work or not? The power for the hazard circuit is fed from the brake light circuit on a 77 from a GR wire. This is fed from the fuse panel. This circuit also feeds the horn, does the horn work? First thing to look at is the brake light fuse. Once you know that is good and you have cleaned the fuse holder contacts, go up the circuit from there looking for voltage. When cleaning contacts or working on pulling any electrical devices from the dash area DISCONNECT THE BATTERY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! When you fry something from inadvertently (or intentionally) shorting a connection you are going to hear a giant sucking sound coming from your wallet. You could burn the 40 to the ground and everything around it too, so be safe and smart.

thanks again for your help. i plan to take this later today and will post on my progress.

 

[jason ladd]

Fantastic!! You solved one problem, now let's fix the other one. Print the two drawings that @GA Archetect was so kind to provide. You never mentioned hazard lights in the OP. You need to be accurate, consistent and concise when asking for help with electrical problems. What may not seem important, can be the nugget of information needed to solve the issue. So do the hazards work or not? The power for the hazard circuit is fed from the brake light circuit on a 77 from a GR wire. This is fed from the fuse panel. This circuit also feeds the horn, does the horn work? First thing to look at is the brake light fuse. Once you know that is good and you have cleaned the fuse holder contacts, go up the circuit from there looking for voltage. When cleaning contacts or working on pulling any electrical devices from the dash area DISCONNECT THE BATTERY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! When you fry something from inadvertently (or intentionally) shorting a connection you are going to hear a giant sucking sound coming from your wallet. You could burn the 40 to the ground and everything around it too, so be safe and smart.

These might help.

View attachment 2485123

View attachment 2485124

than GA Architect. i plan to work on it later today and will update on progress.

 

[jason ladd]

Success! I followed Cromagnon's advice with regard to the order of checking for potential problems. My hazard lights weren't working and my horns were not functional. I obtained a test light and checked the fuse and the light was intermittent on one side and non-existent on the other. I removed the negative cable from the battery and cleaned/lightly sanded the contacts, reinstalled the fuse and voila".....let there be light.
thanks again!