Aftermarket Gauge Lighting
Thread Starter
Instructor
Joined: Jan 2002
Posts: 128
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From: Mayfield KY
Aftermarket Gauge Lighting
Where do you tap into the dash lighting to provide power to the lights when adding aftermarket gauges?? I would like them to dim with the dash lights.
Thanks
Thanks
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
Original Founding Member!
Joined: Jul 1999
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From: Granby, MA
Cruise-In 1, 3, 9. 10 & 11 Veteran
?????
Hopefully some electronic techs can step in.
Tim (Tstar) might be a good source or his buddy (i forget the guys forum name). They have comprehensive background knowledge with the lights and the circuitry.
Hope this helps.
Last edited by XtremeVette; Mar 24, 2008 at 04:08 PM.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
and how is that different then the bulbs that come with the car? They are all 12v bulbs. Except for the gauge cluster that is....but he is not talking about that....he wants to tap into the source to remain dimming function. Is there enough slack (if you will) in the load on that circuit to allow aftermarket lights to be added? or will you blow that circuits fuse cause of an overload.....guess it would depend on the draw the other bulbs are going to place on that dimmer circuit.
Hopefully some electronic techs can step in.
Tim (Tstar) might be a good source or his buddy (i forget the guys forum name). They have comprehensive background knowledge with the lights and the circuitry.
Hope this helps.
Hopefully some electronic techs can step in.
Tim (Tstar) might be a good source or his buddy (i forget the guys forum name). They have comprehensive background knowledge with the lights and the circuitry.
Hope this helps.
Original Founding Member!
Joined: Jul 1999
Posts: 9,037
Likes: 88
From: Granby, MA
Cruise-In 1, 3, 9. 10 & 11 Veteran
Here's the problem ... when you "dim" the IP lamps by rotating the switch, that switch is "internal" to the IPC. The IPC sends out a message on the Class2 data bus so that other components on the bus (radio, door controllers, etc.) can "match" their lighting to the IPC lighting. There is no "external" voltage change that you can pick up on to control non-standard lighting.
Drifting
Joined: Oct 2004
Posts: 1,384
Likes: 8
From: Southwest Virginia
Here's the problem ... when you "dim" the IP lamps by rotating the switch, that switch is "internal" to the IPC. The IPC sends out a message on the Class2 data bus so that other components on the bus (radio, door controllers, etc.) can "match" their lighting to the IPC lighting. There is no "external" voltage change that you can pick up on to control non-standard lighting.
This is true. But I "think" the body computer receives that Class2 command from the IPC and outputs an analog signal for standard incandescent bulbs in things like the dumb (non-computer) HVAC panel. I would have to dig out a manual to be sure, it has been a year or two since I have looked at that.
Drifting
Joined: Oct 2004
Posts: 1,384
Likes: 8
From: Southwest Virginia
hmmmmm bummer....so the computer sends out the signal on the Class 2 data bus for the other components to lower the voltage thus dimming? What if you wired in parelle another bulb to say the door light switch? Would the increase in load cause the fuse to blow or would the computer read the additional load and compensate? or am I not reading you correct?
Paralleling another bulb may work. I would say away from the door bulbs since they are controlled by the door computers. Which HVAC do you have? If it is NOT a dual zone system you can probably get the signal there. DO NOT try this on a dual zone system, they can't drive their own bulbs correctly with a simple factory bulb load.
Safety Car
Joined: Aug 2000
Posts: 4,933
Likes: 30
From: San Rafael CA
This is true. But I "think" the body computer receives that Class2 command from the IPC and outputs an analog signal for standard incandescent bulbs in things like the dumb (non-computer) HVAC panel. I would have to dig out a manual to be sure, it has been a year or two since I have looked at that.There is a YELLOW wire from the BCM to the HVAC that controls the HVAC lamps. It is circuit 390 and is pin B2 on Connector 3 to the BCM (the small one) .....
HOWEVER .... I'd be really cautious putting a load on that wire ... the HVAC lamps are tiny and draw very little load ... you put some 50 watt bulbs on that circuit and your HVAC will be one dark little puppy ....
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Drifting
Joined: Oct 2004
Posts: 1,384
Likes: 8
From: Southwest Virginia
Never noticed that before ....
There is a YELLOW wire from the BCM to the HVAC that controls the HVAC lamps. It is circuit 390 and is pin B2 on Connector 3 to the BCM (the small one) .....
HOWEVER .... I'd be really cautious putting a load on that wire ... the HVAC lamps are tiny and draw very little load ... you put some 50 watt bulbs on that circuit and your HVAC will be one dark little puppy ....
There is a YELLOW wire from the BCM to the HVAC that controls the HVAC lamps. It is circuit 390 and is pin B2 on Connector 3 to the BCM (the small one) .....
HOWEVER .... I'd be really cautious putting a load on that wire ... the HVAC lamps are tiny and draw very little load ... you put some 50 watt bulbs on that circuit and your HVAC will be one dark little puppy ....
Burning Brakes
Joined: Jul 2000
Posts: 1,134
Likes: 1
From: Arlington Texas
Here's some information that I saved a long time ago for when I do my gauges. This was posted a few years ago on Z06vette.com:
I recently installed a 3 gauge cluster (Boost/Fuel-Pressure/IAT) as a "compliment" to my Vortech Supercharger. I used Auto-Meter Sport Comp gauges (because they have black faces with orange pointers kind of like the factory gauges). These gauges use incandescent lamps for backlight illumination.
The C5 uses a Pulse-Width-Modulated (PWM) signal to control the intensity of the dash lamps (and associated lamps). The circuit provides a switched ground that toggles on/off at a high rate. The greater the percentage "on" time, the brighter the dash lamps. The lower the percentage "on" time, the dimmer the dash lamps.
As I found out after my initial install, the dimmer circuit is "current limited". If you attached additional lighting to the circuit, and that lighting draws too much current, the circuit shuts off (and the dash lamps all go out). Alas, the 3-bulb Auto-Meter gauge set up pulls almost 1 amp, and that appears to be too much.
It seemed my only options were to either wire the lamps to 12V with no dimmer, or add a potentiometer in series with the lamps so they'd have their own dimmer. Neither solution was satisfactory, I went looking for alternatives. The circuit below fixes the problem. It "slaves" off the OEM dash lamp circuit, adding a load of only about 20 milliamps, but will allow an additional lighting load of a couple of amps to be controlled by the dashboard dimmer ****.
There are at least two places you can grab the necessary dimmer signal, one is behind the climate control, the other is behind the Traction Control switch on the center console. The Traction Control switch is the easiest to get at, you don't need to disassemble the dash to get at it (it pops right out, and you can feed a wire up inside and along the console without removing a single screw!). The Traction Control switch has a multi-wire connector (6 or 8, I don't remember. And why it needs so many wires for a simple switch, I can't imagine). There is an orange wire all the way at one side of the connector. This is always-on 12V. There is a brown wire right next to it. That brown wire is the dimmer circuit PWM switched ground. The center console Auxiliary 12V power outlet also provides an Orange always-on 12V wire, as well as a Black electrical ground wire, all on a preexisting fused circuit. Very convenient for my purposes. I tapped the Aux power plug wires for the primary power hookups for my circuit.
The MOSFETs are available at Radio Shack for about $2.00, the resistors will cost you another $2.00 bucks. I recommend a small perf-board to solder it all together and some large heat-shrink or electrical tape to insulate it all once assembled.
This probably isn't for you if you're not comfortable wiring things up. If there's enough interest from people who don't have the skills, I might be induced to make up some preassembled kits.
Note that There are cheaper and much smaller ways to do this same thing, but not with parts you can buy at Radio Shack.
Anyway, here's the circuit, for those that are brave of heart.
Circuit:
I recently installed a 3 gauge cluster (Boost/Fuel-Pressure/IAT) as a "compliment" to my Vortech Supercharger. I used Auto-Meter Sport Comp gauges (because they have black faces with orange pointers kind of like the factory gauges). These gauges use incandescent lamps for backlight illumination.
The C5 uses a Pulse-Width-Modulated (PWM) signal to control the intensity of the dash lamps (and associated lamps). The circuit provides a switched ground that toggles on/off at a high rate. The greater the percentage "on" time, the brighter the dash lamps. The lower the percentage "on" time, the dimmer the dash lamps.
As I found out after my initial install, the dimmer circuit is "current limited". If you attached additional lighting to the circuit, and that lighting draws too much current, the circuit shuts off (and the dash lamps all go out). Alas, the 3-bulb Auto-Meter gauge set up pulls almost 1 amp, and that appears to be too much.
It seemed my only options were to either wire the lamps to 12V with no dimmer, or add a potentiometer in series with the lamps so they'd have their own dimmer. Neither solution was satisfactory, I went looking for alternatives. The circuit below fixes the problem. It "slaves" off the OEM dash lamp circuit, adding a load of only about 20 milliamps, but will allow an additional lighting load of a couple of amps to be controlled by the dashboard dimmer ****.
There are at least two places you can grab the necessary dimmer signal, one is behind the climate control, the other is behind the Traction Control switch on the center console. The Traction Control switch is the easiest to get at, you don't need to disassemble the dash to get at it (it pops right out, and you can feed a wire up inside and along the console without removing a single screw!). The Traction Control switch has a multi-wire connector (6 or 8, I don't remember. And why it needs so many wires for a simple switch, I can't imagine). There is an orange wire all the way at one side of the connector. This is always-on 12V. There is a brown wire right next to it. That brown wire is the dimmer circuit PWM switched ground. The center console Auxiliary 12V power outlet also provides an Orange always-on 12V wire, as well as a Black electrical ground wire, all on a preexisting fused circuit. Very convenient for my purposes. I tapped the Aux power plug wires for the primary power hookups for my circuit.
The MOSFETs are available at Radio Shack for about $2.00, the resistors will cost you another $2.00 bucks. I recommend a small perf-board to solder it all together and some large heat-shrink or electrical tape to insulate it all once assembled.
This probably isn't for you if you're not comfortable wiring things up. If there's enough interest from people who don't have the skills, I might be induced to make up some preassembled kits.
Note that There are cheaper and much smaller ways to do this same thing, but not with parts you can buy at Radio Shack.
Anyway, here's the circuit, for those that are brave of heart.
Circuit:
Last edited by thetorch; Mar 24, 2008 at 09:54 PM.
Tech Contributor
Joined: Jan 2007
Posts: 19,475
Likes: 1,171
From: Dyer, IN
Here's some information that I saved a long time ago for when I do my gauges:
I recently installed a 3 gauge cluster (Boost/Fuel-Pressure/IAT) as a "compliment" to my Vortech Supercharger. I used Auto-Meter Sport Comp gauges (because they have black faces with orange pointers kind of like the factory gauges). These gauges use incandescent lamps for backlight illumination.
The C5 uses a Pulse-Width-Modulated (PWM) signal to control the intensity of the dash lamps (and associated lamps). The circuit provides a switched ground that toggles on/off at a high rate. The greater the percentage "on" time, the brighter the dash lamps. The lower the percentage "on" time, the dimmer the dash lamps.
As I found out after my initial install, the dimmer circuit is "current limited". If you attached additional lighting to the circuit, and that lighting draws too much current, the circuit shuts off (and the dash lamps all go out). Alas, the 3-bulb Auto-Meter gauge set up pulls almost 1 amp, and that appears to be too much.
It seemed my only options were to either wire the lamps to 12V with no dimmer, or add a potentiometer in series with the lamps so they'd have their own dimmer. Neither solution was satisfactory, I went looking for alternatives. The circuit below fixes the problem. It "slaves" off the OEM dash lamp circuit, adding a load of only about 20 milliamps, but will allow an additional lighting load of a couple of amps to be controlled by the dashboard dimmer ****.
There are at least two places you can grab the necessary dimmer signal, one is behind the climate control, the other is behind the Traction Control switch on the center console. The Traction Control switch is the easiest to get at, you don't need to disassemble the dash to get at it (it pops right out, and you can feed a wire up inside and along the console without removing a single screw!). The Traction Control switch has a multi-wire connector (6 or 8, I don't remember. And why it needs so many wires for a simple switch, I can't imagine). There is an orange wire all the way at one side of the connector. This is always-on 12V. There is a brown wire right next to it. That brown wire is the dimmer circuit PWM switched ground. The center console Auxiliary 12V power outlet also provides an Orange always-on 12V wire, as well as a Black electrical ground wire, all on a preexisting fused circuit. Very convenient for my purposes. I tapped the Aux power plug wires for the primary power hookups for my circuit.
The MOSFETs are available at Radio Shack for about $2.00, the resistors will cost you another $2.00 bucks. I recommend a small perf-board to solder it all together and some large heat-shrink or electrical tape to insulate it all once assembled.
This probably isn't for you if you're not comfortable wiring things up. If there's enough interest from people who don't have the skills, I might be induced to make up some preassembled kits.
Note that There are cheaper and much smaller ways to do this same thing, but not with parts you can buy at Radio Shack.
Anyway, here's the circuit, for those that are brave of heart.
Circuit:
I recently installed a 3 gauge cluster (Boost/Fuel-Pressure/IAT) as a "compliment" to my Vortech Supercharger. I used Auto-Meter Sport Comp gauges (because they have black faces with orange pointers kind of like the factory gauges). These gauges use incandescent lamps for backlight illumination.
The C5 uses a Pulse-Width-Modulated (PWM) signal to control the intensity of the dash lamps (and associated lamps). The circuit provides a switched ground that toggles on/off at a high rate. The greater the percentage "on" time, the brighter the dash lamps. The lower the percentage "on" time, the dimmer the dash lamps.
As I found out after my initial install, the dimmer circuit is "current limited". If you attached additional lighting to the circuit, and that lighting draws too much current, the circuit shuts off (and the dash lamps all go out). Alas, the 3-bulb Auto-Meter gauge set up pulls almost 1 amp, and that appears to be too much.
It seemed my only options were to either wire the lamps to 12V with no dimmer, or add a potentiometer in series with the lamps so they'd have their own dimmer. Neither solution was satisfactory, I went looking for alternatives. The circuit below fixes the problem. It "slaves" off the OEM dash lamp circuit, adding a load of only about 20 milliamps, but will allow an additional lighting load of a couple of amps to be controlled by the dashboard dimmer ****.
There are at least two places you can grab the necessary dimmer signal, one is behind the climate control, the other is behind the Traction Control switch on the center console. The Traction Control switch is the easiest to get at, you don't need to disassemble the dash to get at it (it pops right out, and you can feed a wire up inside and along the console without removing a single screw!). The Traction Control switch has a multi-wire connector (6 or 8, I don't remember. And why it needs so many wires for a simple switch, I can't imagine). There is an orange wire all the way at one side of the connector. This is always-on 12V. There is a brown wire right next to it. That brown wire is the dimmer circuit PWM switched ground. The center console Auxiliary 12V power outlet also provides an Orange always-on 12V wire, as well as a Black electrical ground wire, all on a preexisting fused circuit. Very convenient for my purposes. I tapped the Aux power plug wires for the primary power hookups for my circuit.
The MOSFETs are available at Radio Shack for about $2.00, the resistors will cost you another $2.00 bucks. I recommend a small perf-board to solder it all together and some large heat-shrink or electrical tape to insulate it all once assembled.
This probably isn't for you if you're not comfortable wiring things up. If there's enough interest from people who don't have the skills, I might be induced to make up some preassembled kits.
Note that There are cheaper and much smaller ways to do this same thing, but not with parts you can buy at Radio Shack.
Anyway, here's the circuit, for those that are brave of heart.
Circuit:
Burning Brakes
Joined: Jul 2000
Posts: 1,134
Likes: 1
From: Arlington Texas
Since you went to the trouble of building your own circuit, did you reduce the load to see if there was a threshold? i.e. if 1 amp was too much, would .75 amps work..etc? Reason I ask, Autometer makes replacement LED's(that draw a fraction of the current) and are a direct replacement for wedge-based bulbs used in aftermarket instrumentation.
As far as using LED's, I replaced the light bulb in my Wideband Commander gauge with an LED replacement for the 168 that came in it. If you use an LED in place of the incandescent you don't need the circuit above. You can wire directly into the harness using the wires described.
Last edited by thetorch; Mar 24, 2008 at 11:29 PM.
Tech Contributor
Joined: Jan 2007
Posts: 19,475
Likes: 1,171
From: Dyer, IN
I didn't build the circuit, a member posted it on Z06vette.com a few years ago and I kept it because I knew I would need it.
As far as using LED's, I replaced the light bulb in my Wideband Commander with an LED replacement for the 168 that came in it. If you use an LED in place of the incandescent you don't need the circuit above. You can wire directly into the harness using the wires described.
As far as using LED's, I replaced the light bulb in my Wideband Commander with an LED replacement for the 168 that came in it. If you use an LED in place of the incandescent you don't need the circuit above. You can wire directly into the harness using the wires described.
Wouldn't that have been a better suggestion? Or were you going to let the poor bastard try to make that circuit, and then tell him all he had to do was install LED's? That's evil......
Burning Brakes
Joined: Jul 2000
Posts: 1,134
Likes: 1
From: Arlington Texas
Tech Contributor
Joined: Jan 2007
Posts: 19,475
Likes: 1,171
From: Dyer, IN
Le Mans Master
Joined: May 2006
Posts: 5,987
Likes: 18
From: DuBois PA
St. Jude Donor '11-'12-'13-'14-'15
I tapped my EL faceplates directly off the back of the Dimmer, these wires;
Everything works fine and the inverter for the faceplates is a large draw I'd imagine...
The Dimmer directly contols the IPC and the Trunk Release/Fog Light switch, and as stated it sends the BCM the Dimming signal which it uses to control the rest of the interior lighting with a PWM signal, some are Positive while other are a PWM on the ground interestingly enough...
I remember reading somewhere in here also that the Tan wire coming out of the HVAC is an "extra" illumination wire, I haven't confirmed that though...
Everything works fine and the inverter for the faceplates is a large draw I'd imagine...
The Dimmer directly contols the IPC and the Trunk Release/Fog Light switch, and as stated it sends the BCM the Dimming signal which it uses to control the rest of the interior lighting with a PWM signal, some are Positive while other are a PWM on the ground interestingly enough...
I remember reading somewhere in here also that the Tan wire coming out of the HVAC is an "extra" illumination wire, I haven't confirmed that though...
Le Mans Master
Joined: May 2006
Posts: 5,987
Likes: 18
From: DuBois PA
St. Jude Donor '11-'12-'13-'14-'15
Yep, that's a direct feed off of the Dimmer **** in the IPC ie not a PWM signal out of the BCM.
Pin 7 is the lighting lead you want and Pin 8 the ground reference.
Pin 7 is the lighting lead you want and Pin 8 the ground reference.
