What bulb is in the switches?

[Sqrly]

I noticed my switches light up at night. The door lock buttons and window switches in the doors and overhead console.

I also noticed a few of them don't light up. Taking the switch apart is not a problem, if they do come apart.

Can anyone tell me what bulb goes in them?

 

[mrrsm]

 

[Sqrly]

@mrrsm

The switches work fine. In my vehicle the white icons and text on the buttons light up on every door and the overhead console when it's dark.

I was hoping to buy bulbs before I take them apart.

(It's not dark yet so you can't see them lit in the pic)

 

[Mooseman]

IIRC, they are just 12v T1 3mm bulbs with wire leads like these:

20pcs Miniature lamp 3mm 12v Indicator Bulb Bombilla Incandescent Filament NEW | eBay

Item : Edison Miniature 3mm Lamp Bulb.

www.ebay.com

 

[TJBaker57]

Here is a sneak peek inside. One picture shows the bulb alongside a standard yellow pencil.

 

[Mooseman]

Those are replaceable twist lock types. AFAIK, the GMT360/370 don't have those except in the rear HVAC control. They are all soldered in place. We do have this big LED mod thread but most of the pictures are long gone. Maybe @Blckshdw still has them somewhere but we may not hear from him until after the hurricane. There are some writeups also on the old site.

 

[Blckshdw]

The front door modules and rear HVAC controls have the twist lock bulbs, everything else is soldered in place. @Sqrly if you're interested in doing an LED conversion, I've been recommending these T4.7 style LEDs. You can get them in various colors, and have built in resistors, so all you have to do is solder the leads in place, and you're on your way.

T4.7 Instrument Panel LED Light,Gauge Cluster Bulbs 10Pack White​

Maybe if I'm bored today, I'll go back into the old LED mod thread and add back the pics as attachments

 

[Sqrly]

@Blckshdw

I can stick those LED's in the twist lock holders too? I'd want everything the same brightness.

I like the idea of using longer lasting parts. Especially when repairing 'non user servicable' parts.

 

[Blckshdw]

The issue with the door modules is the lights don't shine directly under the buttons. There's a clear piece of acrylic, with 2 holes on the driver's side, 1 hole on the passenger side, which the bulb seats in. The light emitted from the sides of the bulb goes through the acrylic, and refracts under the buttons to light them up.

What I ended up doing was soldering some wire to the pads on the circuit board, running them around to each location of the buttons, drilled 5mm holes in the acrylic and solder in an LED in place under each button inserted through the holes. They are very bright, especially the white ones.

 

[Sqrly]

The lights in your picture are way too bright for me.

I was thinking some standard 5mm leds.

 

[Mooseman]

If too bright for you when you install them and test it, use a black marker on the LEDs. I did that on the ones for the steering switches. Worked great.

Now I'm getting the itch to do LEDs on my current TB. I had done it on my 02 EXT many moons ago. I've got a bag of those T4.7 that are just itching to get in. Only my door and steering switches are burnt out.

 

[Blckshdw]

The first time I did them, I used 5mm straw hat LEDs but they weren't bright enough, redid them with 5mm flat tops, and liked that look much better. But when some of them failed after years of use, I found these which were just easier due to not needing resistors.

 

[Sqrly]

I found these at one of my usual outlets. They are 12V with built in resistors and they do come in red, white, green, blue, and yellow. They also come in 3mm and 5mm sizes.

White Clear 12V LED

 

[Blckshdw]

Nice find! I haven't spent time cruising Digikey and Mouser in I don't know how long.

 

[Sqrly]

Nice find! I haven't spent time cruising Digikey and Mouser in I don't know how long.

Thanks. If/when I buy some I'll get a photo of one side by side a stock bulb.

 

[Sqrly]

So I took everything apart before ordering anything.

Master Switch = 2 - 4.7mm Halogen Twist locks
Front Passenger = 1 - 4.7mm Halogen Twist lock
Rear Doors = 1 - 3mm incandescant each, soldered in.
Overhead console = (just the 3 buttons for the tail gate window, mid gate windows and roof) 3 - 4mm(ish) incandescant, soldered in.

I only eyeballed the "4mm(ish)" bulbs. They are smaller then the 4.7mm and larger then the 3mm. It looks like there's plenty of room for the 5mm led.

The rear AC controls are totally different. There is a tiny power led and 2 - 4mm(ish) incandescent bulbs with blue rubbers over them that are soldered in. The 2 bulbs work and when I checked the voltage on the leads while they were on I got just under 6v on each. (Note: Dash light dimmer set to max brightness) The LED is out and I couldn't get a steady voltage reading but it stayed in the mv range so I'm just going to leave that one alone.

The AC controls have a "Made in Mexico" sticker on them so I'm assuming it's the stock part.

Rear Door



Overhead Console



Rear AC Controls

 

[TJBaker57]

incandescent bulbs with blue rubbers over them that are soldered in

These look like the bulbs used in the 4WD mode switch.

 

[Sqrly]

These look like the bulbs used in the 4WD mode switch.

They do indeed. The rubber cover can be removed. I took one off with my fingernails to see what kind of bulb was under it. I see that PCB also has some LED's. You didn't happen to get a pic of the backside of that PCB did you?

In the doors and overhead console I can trace the circuit to see that the bulbs are getting voltage from the connector, so they are getting fed 12v. The led on the ac control is not connected directly to the 12v source. I'm curious what the voltage rating of the LED is.

Luckily, all my dash lights work. It's just a few in the doors and overhead console that are out.

 

[TJBaker57]

They do indeed. The rubber cover can be removed. I took one off with my fingernails to see what kind of bulb was under it. I see that PCB also has some LED's. You didn't happen to get a pic of the backside of that PCB did you?

In the doors and overhead console I can trace the circuit to see that the bulbs are getting voltage from the connector, so they are getting fed 12v. The led on the ac control is not connected directly to the 12v source. I'm curious what the voltage rating of the LED is.

Luckily, all my dash lights work. It's just a few in the doors and overhead console that are out.

I do have pictures of the reverse side, let me have a look...




The power source for both the LEDs and incandescent lights is the BCM. The BCM outputs 2 separate powers for lighting, one for the LEDs and another for the incandescents. The BCM uses the dimmer switch as in input sensor to adjust the power signals out to the various lamps. I am fairly certain the 2 power signals are of different natures. I suspect at least one of them is a PWM signal source.

 

[Sqrly]

The power source for both the LEDs and incandescent lights is the BCM. The BCM outputs 2 separate powers for lighting, one for the LEDs and another for the incandescents. The BCM uses the dimmer switch as in input sensor to adjust the power signals out to the various lamps. I am fairly certain the 2 power signals are of different natures. I suspect at least one of them is a PWM signal source.

You just stated everything I sought to learn by looking at it.

Can you figure out what voltage the LED's are? 3mm reds and yellows were typically 2V but these days you can get any color in a wide variety of voltages.

I bet they used the same ones throughout the vehicle.

 

[TJBaker57]

You just stated everything I sought to learn by looking at it.

Can you figure out what voltage the LED's are? 3mm reds and yellows were typically 2V but these days you can get any color in a wide variety of voltages.

I bet they used the same ones throughout the vehicle.

I can tell you this straight away....

all led lamps that dim in response to the dimmer switch get exactly the same voltage. The ONE power source that comes from the BCM for led lamps goes to ALL the LEDs that dim.

Same can be said of ALL the incandescent lamps that dim, they ALL share the exact same circuit.


I can mock up a dimming input to one of my BCM bench test setups and measure what the BCM outputs, both minimum and maximum. I actually did just this not so very long ago but have forgotten what I found!!

 

[TJBaker57]

The incandescent bulbs are powered from BCM Connector 3, terminals B1 and B2. I measured that source is a PWM signal at 128 hz and operates from a max of 85% duty cycle down to about 11% duty cycle. Measuring DC voltage with an autoranging DMM I see 12.4 volts down to zero there.



The LEDs are powered from BCM Connector 3, terminal B14. I measured that source at a steady state DC (not PWM) from a maximum of battery voltage down to between 7.5 to 8.5 Volts DC depending on the battery voltage. With a charger inputting about 14.5 volts to my benchtop I saw tht same voltage passed right on the the lamps.

My measurements are with minimal lighting load on the circuits.

 

[TJBaker57]

led lamps that dim in response to the dimmer switch get exactly the same voltage

ALL the incandescent lamps that dim, they ALL share the exact same circuit

Well this may not be 100% accurate !!

I just noted that in wiring diagrams I do not see these power sources going to either the Driver or Passenger door modules.

It sort of looks like these two modules AND the cluster adjust their own brightness levels in response to serial data messages from the BCM.

I just had a look at that and I do see serial data messages from my test BCM as I adjust my 'dimmer' switch (potentiometer).




Not shown here are acknowledgment messages from the cluster. The cluster brightens and dims the odometer and PRND321 display directly, not relying on the LED power from the BCM. And it at least looks like the DDM and PDM do likewise for their lights?

I learn something new every day. Which is good because I will likely forget several of them in a day or two.

 

[Sqrly]

I replaced the bulbs in the switch in the overhead console with the 3mm LED's I linked earlier. They appear to be just a little brighter once installed, due to the fact these LED bulbs have a 120 degree lens and, they do dim evenly with the rest of the lights.

I'm pleased with the result as they are very close in brightness to the rest of the stock lights. Remember, I am doing this because several bulbs are out and I'm using LED's simply for the longer life span. Next is putting the 5mm bulbs in the front door switches. My plan is to reuse the twist lock bases. (Note to self: add polarity markings to twist lock bases and PCB's.)


Comparison to stock bulb on the desk @ 12V, 90 degree angle. (Bottom is stock.)



Finished switch on the desk.



Finished switch in vehicle at night from back seat. (upper most lights)

 

[Sqrly]

I finished replacing the bulbs in the front door switches. They also seem only a little bit brighter then stock and they dim evenly with the rest of the lighting.

Soldering bulbs in place would have been quicker and easier but I wanted to keep it as close to original as possible.

FYI: If either front door window/lock switch is disconnected the rest of the lighting malfunctions. As in, the dome lights stay on unless turned off manually and the marker lights don't flash when you lock/unlock the vehicle with the remote. There's probably more but the point is, your exterior lights may malfunction or your battery might get drained if you leave one of the switches disconnected too long.

Drivers door switch with polarity marked. (I added red + signs to photo, the yellow paint is my permanent marking.)



Passenger door switch with polarity marked. (Yellow dot not applied yet)



Bulb after assembly with important notes.



Additional Note.

 

[TJBaker57]

FYI: If either front door window/lock switch is disconnected the rest of the lighting malfunctions. As in, the dome lights stay on unless turned off manually and the marker lights don't flash when you lock/unlock the vehicle with the remote. There's probably more but the point is, your exterior lights may malfunction or your battery might get drained if you leave one of the switches disconnected too long

Interesting....

The BCM depends on serial data messages from the door modules to know whether those doors are open or closed. And it is the BCM that turns on these interior lights. I wonder if lacking the information from a door module the BCM defaults to turning interior lamps on as if one of those doors are open.

 

[Sqrly]

Interesting....

The BCM depends on serial data messages from the door modules to know whether those doors are open or closed. And it is the BCM that turns on these interior lights. I wonder if lacking the information from a door module the BCM defaults to turning interior lamps on as if one of those doors are open.

Though I understand what your saying, it is all new to me and I have no experience with the tools your reffering to.

I was blissfully unaware that cars had networks in them until I started troubleshooting this one.

I do however appreciate your posts and find them very interesting as I always like to learn.

 

[TJBaker57]

I do however appreciate your posts and find them very interesting as I always like to learn.

Rarely, if ever, do I actually have the vehicle troubles that I explore. I do like to dig into things and learn how they really work.