Dome/Cargo/Courtesy Light Question

Leeunc1

Junior Member
Joined
Sep 18, 2021
Posts
6
Reaction score
0
Location
North Texas
First Name
Lee
Truck Year
1987
Truck Model
R10
Engine Size
5.7
I just fixed (replaced wiring) for the Dome and Cargo Light. New harness from fuse panel (power to battery) and spliced white (ground) wire to door jamb switch all the way to each light.

Both lights now work when opening each door. Both lights shut off when closing door. Cargo light switch works also. Issue is the under dash courtesy light does not work unless turning the dimmer switch to "on". Is this normal? Could it be a possible headlight switch?

It would seem all wiring (white ground wire) from both door jamb switches and headlight switch are good to the courtesy light.

Lost now and any help is appreciated.
 

Leeunc1

Junior Member
Joined
Sep 18, 2021
Posts
6
Reaction score
0
Location
North Texas
First Name
Lee
Truck Year
1987
Truck Model
R10
Engine Size
5.7
Truck is a 1987 R10 reg. cab
 

SirRobyn0

Full Access Member
Joined
Dec 6, 2019
Posts
2,952
Reaction score
3,064
Location
In the woods in Western Washington
First Name
Rob
Truck Year
1984
Truck Model
C20
Engine Size
350
Without looking at a wiring diagram, I can't tell you if that is normal or not, but it would seem unlikely to be a headlight switch to me, and those lights come on when you activate that way.

There is a wiring diagram section in the forums, and if I wasn't on my phone I'd give you a direct link. But you should be able to look at a schematic to see if the courtesy lights are wired to come on with the doors.
 

Leeunc1

Junior Member
Joined
Sep 18, 2021
Posts
6
Reaction score
0
Location
North Texas
First Name
Lee
Truck Year
1987
Truck Model
R10
Engine Size
5.7
I have a diagram and seems that the the all lights (dome/cargo/courtesy) are connected in a parallel circuit to both door switches and headlight switch. Once one of the switches creates a short, all lights should come on.

What I don't understand is why both dome and cargo work when either door is open, it should also light the courtesy light since they are connected in parallel. Not sure what I am missing.
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
3,379
Reaction score
4,479
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
Do the dome and cargo only work with door switches or also with the headlight switch?
Sounds like courtesy lamp is wired only to headlight switch and others only to the doors.
Bad splice or missed one connect under the dash is what I’d look for.
 
Last edited:

Leeunc1

Junior Member
Joined
Sep 18, 2021
Posts
6
Reaction score
0
Location
North Texas
First Name
Lee
Truck Year
1987
Truck Model
R10
Engine Size
5.7
I just checked, the dome/cargo light does not come on when the the dimmer switch is turned on, just the courtesy light. I checked wiring from the RH jamb switch, which runs directly to the courtesy light. Also on the courtesy light, a white wire directly to the LH jamb switch and a white wire to the headlight switch.

This is what confuses me, when the RH door is open it creates the ground all the way through the courtesy light to the dome and cargo light. Seems all 3 would light.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
7,764
Reaction score
4,374
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Do the dome and cargo only work with door switches or also with the headlight switch?
Sounds like courtesy lamp is wired only to headlight switch and others only to the doors.
Bad splice or missed one connect under the dash is what I’d look for.
i know my truck has some corroded connections here or there, but if i open my passenger door, the floor comes on, but faint, and the dome on. if i turn the switch, floor goes full, dome stays as it was. my driver door doesnt turn lights on because the switch mounting spot does not exis Lol.

Anyway, that tells me that it prob should..?if the cargo light is used to cuto ut the lights, doesnt it make the floor stay on only?
 

Leeunc1

Junior Member
Joined
Sep 18, 2021
Posts
6
Reaction score
0
Location
North Texas
First Name
Lee
Truck Year
1987
Truck Model
R10
Engine Size
5.7
Thank you, at least I know that both should turn on. As the poster stated above, it has to be a splice somewhere I cannot see. Will take dash/glove box, etc put and trace each wire.

Thank you!
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
7,764
Reaction score
4,374
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
heres a dash piece cut out of a cab upside down to give you an idea of what the wiring does by the light. orange with black stripe i believe is the lead from the light to the dome and orange is the power to the light.. i think.
.
You must be registered for see images attach
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
3,379
Reaction score
4,479
Location
Washington
First Name
Todd
Truck Year
1986
Truck Model
K20
Engine Size
454
i know my truck has some corroded connections here or there, but if i open my passenger door, the floor comes on, but faint, and the dome on. if i turn the switch, floor goes full, dome stays as it was. my driver door doesnt turn lights on because the switch mounting spot does not exis Lol.

Anyway, that tells me that it prob should..?if the cargo light is used to cuto ut the lights, doesnt it make the floor stay on only?
No, cargo light switch doesn’t affect the dome lamp. Or it shouldn’t if it’s wired like factory
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
7,764
Reaction score
4,374
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
No, cargo light switch doesn’t affect the dome lamp. Or it shouldn’t if it’s wired like factory
i thought it could kill the dome but the floor stayed on
how many stops does the switch have? 2 or 3? Maybe the one on my dads gmt400 was different but ithought the switch was the same. i suppose how it was wired in may change
 

RoryH19

Full Access Member
Joined
Aug 21, 2015
Posts
1,668
Reaction score
1,054
Location
Texas
First Name
Rory
Truck Year
1987
Truck Model
R10 Silverado SWB
Engine Size
350 TBI
Not 100% sure of the question but here are the details for my 87 r10.
With door closed I can turn the inside cab light and floor light on with headlight switch. If the cargo switch is also turned on it will also light up.
With headlight switch off and door opened the floor and cab lights come on. Also if the cargo lamp switch is on it lights up too.
The wiring of my truck has never been hacked, modified or removed.
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
7,764
Reaction score
4,374
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
Not 100% sure of the question but here are the details for my 87 r10.
With door closed I can turn the inside cab light and floor light on with headlight switch. If the cargo switch is also turned on it will also light up.
With headlight switch off and door opened the floor and cab lights come on. Also if the cargo lamp switch is on it lights up too.
The wiring of my truck has never been hacked, modified or removed.
appreciated definitely cant claim any of the things ive seen are wiring virgins and then anything my dad has... oh god... im not a electrical engineer and Ill use a cheapout connection if I deem it sufficient or adequate enough for the situation, but man everyone in my family who touches wiring except literally my step dad who is a fire fighter, he will go above for even the simplest wiring thing for safety.... I dont know how im alive or any of them just by association lol. That can start and end at car electrical too!

Screws to hold the positive post on
Tape only for wires
10 year old batteries and bad connections near combustibles

Thank god rory kind of people can exist,i need to buy a truck from someone like him some day and see the difference
 

RoryH19

Full Access Member
Joined
Aug 21, 2015
Posts
1,668
Reaction score
1,054
Location
Texas
First Name
Rory
Truck Year
1987
Truck Model
R10 Silverado SWB
Engine Size
350 TBI
appreciated definitely cant claim any of the things ive seen are wiring virgins and then anything my dad has... oh god... im not a electrical engineer and Ill use a cheapout connection if I deem it sufficient or adequate enough for the situation, but man everyone in my family who touches wiring except literally my step dad who is a fire fighter, he will go above for even the simplest wiring thing for safety.... I dont know how im alive or any of them just by association lol. That can start and end at car electrical too!

Screws to hold the positive post on
Tape only for wires
10 year old batteries and bad connections near combustibles

Thank god rory kind of people can exist,i need to buy a truck from someone like him some day and see the difference

Too funny. Yes OCD has its plus side.
 

Forum statistics

Threads
35,828
Posts
755,054
Members
24,840
Latest member
KC_Stuart
Top