Author Topic: Courtesy light issue  (Read 653 times)

Offline Jeff86inMS

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Courtesy light issue
« on: May 02, 2022, 06:40:22 PM »
Looking to trace down an electrical issue related to the under dash courtesy light.  I have a 1986 custom deluxe.  There is only one door jam switch on the drivers side, passenger side looks to be plugged from the factory.  I have replaced the light socket under the dash with one from  .  I know itís getting power because the orange power wire shorted on the dash as I was testing it and it blew the fuse.  I disconnected the battery, spliced in the new socket, still doesnít work.  The switch only has one wire to it, but the switch has two blades for a connection.  Should there be two wires going to that switch?  Did I mention I hate auto electrical issues?  I am determined to fix it though!  Any help would be greatly appreciated!!


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Offline Mike81K10

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Re: Courtesy light issue
« Reply #1 on: May 02, 2022, 08:27:37 PM »
The door switch is a ground when the door opens. If you have power to the switch it could be the bulb or a ground problem.

Offline bd

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Re: Courtesy light issue
« Reply #2 on: May 03, 2022, 12:56:05 AM »
How many wires connect to the courtesy lamp socket?
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Jeff86inMS

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Re: Courtesy light issue
« Reply #3 on: May 03, 2022, 04:56:17 AM »
Because itís an aftermarket socket, there is a white wire for power (according to the directions) and a black wire for ground.  I connected these to the corresponding wires there were cut from the old socket.  Came with a new bulb as well. 


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Offline bd

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Re: Courtesy light issue
« Reply #4 on: May 03, 2022, 09:44:32 AM »
Not all courtesy lamps operate when the doors open.  Have you tried rotating the headlamp switch knob all the way CCW?  If the lamp works by rotating the knob, you can add door open lamp control by installing an additional wire to the door jamb switch.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Jeff86inMS

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Re: Courtesy light issue
« Reply #5 on: May 03, 2022, 09:48:36 AM »
No, tried that as well.  Light does not come on when rotating headlight switch.  Could it be the headlight switch thatís defective?  Head lights come on when switch is pulled.


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Offline bd

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Re: Courtesy light issue
« Reply #6 on: May 03, 2022, 11:34:52 AM »
Ensure that the bulb and socket are correctly matched.  How many terminals are on the bottom of the courtesy lamp bulb?  Are there corresponding terminals at the bottom of the socket? 

Using a test light, validate power and ground by probing the socket contacts with the bulb removed.  One socket terminal should be constant B+.  The remaining terminal should be switched to ground.  If you verify power and the ground side is continuously open, try jumping the ground side momentarily to bare sheet metal to see if the bulb illuminates.  This will verify that the bulb is making good electrical contact in the socket. 

To address one of your earlier questions, the door jamb switch has two terminals.  The terminals are insulated from one another yet ground simultaneously when the door opens.  One terminal is for the ignition key warning buzzer.  The other terminal is for the door open courtesy lamp option when installed at the factory.  The left and right door jamb switches, when both are installed, are wired in parallel.  Only the left door jamb switch connects to the key warning buzzer circuit.

The headlamp switch grounds the courtesy lamp circuit (identified by the white wire connected to the switch) with full CCW rotation of the knob.  For the courtesy lamps to illuminate via the headlamp switch, the headlamp switch frame must be suitably grounded.  There is a terminal protruding from the headlamp switch frame for this purpose.  It should have a black wire connecting the switch frame to the left kick panel.  Often, this ground wire is missing, which forces the headlamp switch to ground directly to the instrument panel.  Unfortunately, since the instrument panel is painted, the ground can be poor when the jumper is absent; you may need to add it.  For images see Diagnosing dash instrument lights near the bottom of the page.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Jeff86inMS

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Re: Courtesy light issue
« Reply #7 on: May 03, 2022, 05:17:58 PM »
Wow!  That is pretty comprehensive right there!  Thanks!  Stopped on the way home from work to get a tester.  Will start tracing it down following those steps.  Thanks for this great info.  Will let you know what I find out.  I suspect itís something with the ground.  I will update after some testing.


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Offline Jeff86inMS

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Re: Courtesy light issue
« Reply #8 on: May 19, 2022, 02:53:21 PM »
Okay, got the light to come on with the headlight switch, but does not come on when opening the door, though I have replaced the door jam switch as well. 

The wire from the door switch goes to the back of the fuse panel, so I canít see what that wire is connected to.

My headlight switch is a 7-pin and there is a ground connected to the ground tab via the harness plug. 

Any suggestions?


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Offline Mike81K10

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Re: Courtesy light issue
« Reply #9 on: May 19, 2022, 09:30:13 PM »
The door jam switch may have been aftermarket and would simply be a ground spliced into the ground side of the light. Still will not work unless the is constant power to the light. When you open the door ground is supplied to the ground side of the light. I have not looked at the diagram, but if the headlamp switch has to be turned to apply power there will be a problem with using the door jam switch as it is only a ground.

Offline Jeff86inMS

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Re: Courtesy light issue
« Reply #10 on: May 20, 2022, 06:53:57 AM »
Okay, so the hound wire coming out ok the light socket goes to the headlight switch via the factory harness (bulk wire), so if I understand what you are saying, I should ďspliceĒ into the blk wire coming from the socket and connect the other end to the door jam switch.  That way, I can manually turn the light on with the headlight switch while inside the cab, OR the light would otherwise come on when the door is opened because the ground would be supplied.  Is that correct?

Thanks for the input!  I know this seems inconsequential to some, but I like things to work as they should.


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Offline bd

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Re: Courtesy light issue
« Reply #11 on: May 20, 2022, 11:22:38 AM »
...To address one of your earlier questions, the door jamb switch has two terminals.  The terminals are insulated from one another yet ground simultaneously when the door opens.  One terminal is for the ignition key warning buzzer.  The other terminal is for the door open courtesy lamp option when installed at the factory.  The left and right door jamb switches, when both are installed, are wired in parallel.  Only the left door jamb switch connects to the key warning buzzer circuit.

The headlamp switch grounds the courtesy lamp circuit (identified by the white wire connected to the switch) with full CCW rotation of the knob.  For the courtesy lamps to illuminate via the headlamp switch, the headlamp switch frame must be suitably grounded...


If you intend to work on the vehicle wiring you really should refer to the factory diagrams to become comfortable and familiar with them.  You have the right idea.  Run an 18-gauge white wire (to maintain consistency with the factory) from the unused terminal of the door jamb switch to the white wire connecting to the headlamp switch.  Voila!

Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Jeff86inMS

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Re: Courtesy light issue
« Reply #12 on: May 20, 2022, 11:52:06 AM »
Thanks BD
All of the wiring going to the headlight switch is in a wiring plug.  How do I connect the additional wire to that plug?  Or go I simply splice into that wire?

Iím trying to learn as much as I can about the wiring, but wiring diagrams are confusing at this point to me.  I can follow the wires on the diagram, but am finding it difficult to relate to the vehicle.  I am determined though and will keep at it.  Thanks again for your help!


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Offline bd

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Re: Courtesy light issue
« Reply #13 on: May 20, 2022, 02:29:37 PM »
Method A:
Remove the white wire from the headlamp switch connector, cut off the existing terminal, and then crimp (using a dedicated electrical terminal crimper) and solder (using 60 Pb/40 Sn rosin core solder) a new terminal onto the end of the original and new wires combined together.  DO NOT TWIST the wires together before crimping!

Use the tool imaged below or substitute a thin blade screwdriver to release the terminal from the headlamp switch connector by slightly depressing the tab on the back of the terminal.  Each terminal cavity has a narrow channel exposed on the front of the connector for the purpose of inserting the tool.





Replace the terminal using a brass or ďtinnedĒ brass Packard 56 style terminal, imaged below.





The tools and terminals should be readily available from most auto parts stores.

Method B:
Inline splice the new white wire to the existing white wire that connects to the headlamp switch.
« Last Edit: May 20, 2022, 07:42:46 PM by bd »
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)