Brake light issues

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Fjordlander

Fjordlander

Full Access Member
Joined
Oct 10, 2022
Posts
104
Reaction score
39
Location
USA
First Name
Kyle
Truck Year
1976
Truck Model
Scottsdale K10
Engine Size
V8
Hello! The brake lights stopped working in my 76 K10 but all other lights continued to work fine. The brake light switch was in rough shape so I replaced it but instead of the brake lights working, now the brake light bulbs flash instead of the indicator bulbs when the blinker is turned on. I've tried new bulbs, cleaning up the grounds, and cleaning the sockets but the results are the same. Any suggestions on what to do next?
 
Fjordlander

Fjordlander

Full Access Member
Joined
Oct 10, 2022
Posts
104
Reaction score
39
Location
USA
First Name
Kyle
Truck Year
1976
Truck Model
Scottsdale K10
Engine Size
V8
I ordered new sockets but would I be better off getting a whole new rear wiring harness? All the wiring in my truck is a mess
 
Goldie Driver

Goldie Driver

Full Access Member
Joined
Mar 19, 2018
Posts
4,047
Reaction score
6,640
Location
Houston, Texas
First Name
Britt
Truck Year
1980
Truck Model
GMC K1500 Suburban
Engine Size
350
Fjordlander said:
Hello! The brake lights stopped working in my 76 K10 but all other lights continued to work fine. The brake light switch was in rough shape so I replaced it but instead of the brake lights working, now the brake light bulbs flash instead of the indicator bulbs when the blinker is turned on. I've tried new bulbs, cleaning up the grounds, and cleaning the sockets but the results are the same. Any suggestions on what to do next?
Click to expand...
I am no electrical guru, but , the brake light bulbs and turn signal bulbs for the rear are one and the same. The brake light switch is the one that is above the brake pedal and activated by it. Are you sure the bulbs are the correct ones ?

1157 is the part number.
 
R

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,593
Reaction score
9,107
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Wiggle the turn signal switch see if you can get the signals to go off and the brake lights to work. The turn signal switch controls power for the brake light and turn signals
 
Last edited:
Fjordlander

Fjordlander

Full Access Member
Joined
Oct 10, 2022
Posts
104
Reaction score
39
Location
USA
First Name
Kyle
Truck Year
1976
Truck Model
Scottsdale K10
Engine Size
V8
Goldie Driver said:
I am no electrical guru, but , the brake light bulbs and turn signal bulbs for the rear are one and the same. The brake light switch is the one that is above the brake pedal and activated by it. Are you sure the bulbs are the correct ones ?

1157 is the part number.
Click to expand...
My truck has a mini bulb for the blinker and 1157 for the brake light
You must be registered for see images attach
the blinker bulb is the little one on the right
 
Fjordlander

Fjordlander

Full Access Member
Joined
Oct 10, 2022
Posts
104
Reaction score
39
Location
USA
First Name
Kyle
Truck Year
1976
Truck Model
Scottsdale K10
Engine Size
V8
Ricko1966 said:
Wiggle the turn signal switch see if you can get the signals to go off and the brake lights to work. The turn signal switch controls power for the brake light and turn signals
Click to expand...
Just tried that and no luck
 
R

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,593
Reaction score
9,107
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Fjordlander said:
My truck has a mini bulb for the blinker and 1157 for the brake light
You must be registered for see images attach
the blinker bulb is the little one on the right
Click to expand...
The 1157 does all three functions. It is brake tail and turn. That's why the turn signal switch controls power to turn signal and brake. It kills brake light power to the 1157 when the turnbsignal is on pull the tail light housing see if someone has splicingbwires behind it.
 
Fjordlander

Fjordlander

Full Access Member
Joined
Oct 10, 2022
Posts
104
Reaction score
39
Location
USA
First Name
Kyle
Truck Year
1976
Truck Model
Scottsdale K10
Engine Size
V8
Ricko1966 said:
The 1157 does all three functions. It is brake tail and turn. That's why the turn signal switch controls power to turn signal and brake. It kills brake light power to the 1157 when the turnbsignal is on pull the tail light housing see if someone has splicingbwires behind it.
Click to expand...
Interesting. It looks like someone had spliced the wires at one point but now they're just connected back together. I'll double check the connections.

What is the mini bulb for? That used to blink when I put the turn signal switch on
 
Goldie Driver

Goldie Driver

Full Access Member
Joined
Mar 19, 2018
Posts
4,047
Reaction score
6,640
Location
Houston, Texas
First Name
Britt
Truck Year
1980
Truck Model
GMC K1500 Suburban
Engine Size
350
Fjordlander said:
Interesting. It looks like someone had spliced the wires at one point but now they're just connected back together. I'll double check the connections.

What is the mini bulb for? That used to blink when I put the turn signal switch on
Click to expand...
That is a side marker light. As wired by GM it comes on with the parking lights and would not blink.
 
Fjordlander

Fjordlander

Full Access Member
Joined
Oct 10, 2022
Posts
104
Reaction score
39
Location
USA
First Name
Kyle
Truck Year
1976
Truck Model
Scottsdale K10
Engine Size
V8
Goldie Driver said:
That is a side marker light. As wired by GM it comes on with the parking lights and would not blink.
Click to expand...
I think I'm going to order a new harness for the rear. None of the lights seem to be doing what they're supposed to do lol
 
WFO

WFO

Full Access Member
Joined
Jan 6, 2017
Posts
3,713
Reaction score
5,102
Location
Texas Panhandle
First Name
Dan
Truck Year
1986
Truck Model
K20
Engine Size
350
Fjordlander said:
I think I'm going to order a new harness for the rear. None of the lights seem to be doing what they're supposed to do lol
Click to expand...
I would expose those wires, and use a test light or voltage meter on each wire to determine the 3 functions of the tail light.
If you have all 3 functions the wires are probably crossed, and you can resplice them accordingly.
Also check continuity from those wires to the bulb socket.
 
Fjordlander

Fjordlander

Full Access Member
Joined
Oct 10, 2022
Posts
104
Reaction score
39
Location
USA
First Name
Kyle
Truck Year
1976
Truck Model
Scottsdale K10
Engine Size
V8
I ended up replacing the rear harness, the bulb sockets, all the rear ground wires, the blinker flasher, and I redid the connect of the white wire under the steering column that runs to the stop light switch and after all that, I finally have brake lights!

The only weird thing was midway through, my dome light started turning on anytime I turned on the headlights and my instrument lights quit working. I didn't touch any wires that would have had anything to do with that but the PO made a real mess of the wiring so who knows lol. I'm planning to pull apart the dash and run new wires that match the OEM wiring diagram so hopefully that will solve my remaining issues
 
Fjordlander

Fjordlander

Full Access Member
Joined
Oct 10, 2022
Posts
104
Reaction score
39
Location
USA
First Name
Kyle
Truck Year
1976
Truck Model
Scottsdale K10
Engine Size
V8
I replaced the light switch and the printed circuit for the dash instruments but I'm still have the same issue where if I turn on the headlights the dome light turns itself on and none of the dash lights except the blinker indicators work.
Also, as soon as I turn on the headlights, this 20v fuse burns out. Any suggestions for me?
You must be registered for see images attach
 
R

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,593
Reaction score
9,107
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Fjordlander said:
I replaced the light switch and the printed circuit for the dash instruments but I'm still have the same issue where if I turn on the headlights the dome light turns itself on and none of the dash lights except the blinker indicators work.
Also, as soon as I turn on the headlights, this 20v fuse burns out. Any suggestions for me?
You must be registered for see images attach
Click to expand...
You probably have more than 1 problem.Headlight switch is wired wrong. It picks up power for the headlights from a fusible link,not the tail light fuse.You probably also have a short in a headlight wire. Headlight switch picks up power for the taillights from the tail light fuse. You need to grab a wiring schematic and look real hard at how you have things run in comparison to the schematic.
 
Last edited:
You must log in or register to reply here.

Similar threads

P
Brake light grounding
Replies
3
Views
556
Ricko1966
R
P
Brake light issue I can't get smart to
Replies
7
Views
516
Jgonick
Jgonick
Mark80K15
No driver's side rear turn signal or brake light, because no power at bulkhead
Replies
12
Views
672
Mark80K15
Mark80K15
C
Brake Light and Turn Signal Issue 82 c10
Replies
10
Views
740
Cpmskinny
C
T
Passenger turn & side marker lights trouble
Replies
4
Views
429
laurat
L

Latest posts

Forum statistics

Threads
44,401
Posts
956,721
Members
36,714
Latest member
MartinK5
Top