Help! interior background illumination lights not working

[Jessica19699]

Hello,

I have a 1992 corvette and driving to work this morning I noticed that my interior illumination lights wasn't working they always had before. My headlights,turn signals,brake lights,dash lights,aftermarket stereo,and ac/heater buttons light up everything outside the car works but the door,rear view mirror, headlight on/off knob,fuel and miles/per gallon cluster on the dash and ac/heater illumination lights don't work.is there a fuse for this and if so where is it located? I know about the dimmer control on the headlight knob and it is turned up to where it should be for them to work and the interior lights do come on but nothing else.Any other ideas on what can be wrong would greatly be appreciated.

Thanks,
Jessica

 

[ecss]

If the background lights are out for the following items

PRND indicator console background light for automatic transmission.
LH, RH Power seat background lights
Driver Information Center background lights
HVAC control head background lights
Light Switch background lights
LH, RH Door Lamp background lights
Power Mirror switch background light
Power Window switch background lights
Rear view mirror console illumination
Radio head background lighting. (You have an aftermarket radio so this doesn't apply).

I don't have documentation for a 92 but a 91 had a INST LPS 5 amp fuse in the end of dash fuse panel. :L

If the fuse is good my educated guess is the Incandescent Lamp driver Module is bad. ad

To replace the module.
You need to remove the driver side foot well panel that contains the foot well courtesy lamp.
Then remove the carpeted knee panel which will expose a metal panel that also needs to be removed.
Bolted on the driver side of the steering column towards the middle of the column is the Incandescent
Driver Module.
It has a large silver colored heat sink and a white molex connector plug.

If the module is bad you have two choices.

Purchase a new replacement. AC Delco D1509B around $30 on Amazon.
Or replace the transistor which is a 2n3055. Very common transistor around $4.00
from an electronic store. Some Radio Shacks stock the part. Part # 276-2041

This is a picture of where it's located.
The bottom picture is a link and shows what the module looks like.

 

[Jessica19699]

ecss thanks so much for the info I will check this out, I hope it is as simple a fix as it seems.

 

[Jessica19699]

ECSS so I replaced the INST LPS 5 amp fuse except mine was a 3 amp fuse and that didn't fix it so my next step will be to purchase the Incandescent Lamp driver Module and hope that fixes it. I do have another question though I seen others speak of a lighting sensor on the dash panel where all the buttons for mpg, odometer, fuel check etc. are and I located where it is on my car, does that light sensor there have anything to do with the night time illuminations lights working? and if so does it or can it go bad and if so how do you go about replacing it? I appreciate all your help

 

[ecss]

ECSS so I replaced the INST LPS 5 amp fuse except mine was a 3 amp fuse and that didn't fix it so my next step will be to purchase the Incandescent Lamp driver Module and hope that fixes it. I do have another question though I seen others speak of a lighting sensor on the dash panel where all the buttons for mpg, odometer, fuel check etc. are and I located where it is on my car, does that light sensor there have anything to do with the night time illuminations lights working? and if so does it or can it go bad and if so how do you go about replacing it? I appreciate all your help

The ambient light sensor does effect the back lighting brightness for the dash cluster LCD but I don't believe it effects the back lighting for the other back lighting incandescent bulbs.

You can test the ambient light sensor by turning the headlight switch to Park.
No need to turn on the ignition. Shine a light on the sensor and the dash cluster LCD back lighting should brighten. Place your finger over the sensor and the back lighting should dim.

If you don't have a flash light just block the sensor with your finger and you should see a change in the back lighting brightness. :L

The sensor has a slow reaction time so give it a second for the display to change brightness.

To verify the Incandescent Power Driver Module is the problem.
After you gain access to the module, unplug the THREE PIN CONNECTOR.

One pin on the connector should have a Brown wire.
One pin on the connector should have a Green wire.
One pin on the connector should have two wires. (Purple/White)

After you disconnect the connector, take a jumper clip (piece of wire or paper clip and connect the Brown wire to the Green wire at the connector.

This bypasses the Incandescent Power Module and the dimmer switch.

Turn the headlight switch to Park. (No need to turn the ignition On).

All of the incandescent back lighting should be working again at full brightness.

If they don't work the module is not the problem.

Post your result. You can verify the back lighting circuit is working by doing some diagnostics using the CCM which controls the incandescent back lighting brightness via the Incandescent Power Driver module.



The ambient light sensor is the small round item top left.

 

[Jessica19699]

so when you say the ambient light sensor does effect the back lighting brightness for the dash cluster LCD are you referring to the speedometer ,tachometer etc.. cause that is the only thing interior that works now in the dark.. the courtesy light works when I flip the headlight switch thing all the way to the top, and the ac/heater buttons light up indicating what setting is on (vents ,feet, defrost ect) but no other illumination is lit on the ac/heater or anything else, I did order the Ac Delco part from amazon.

 

[ecss]

so when you say the ambient light sensor does effect the back lighting brightness for the dash cluster LCD are you referring to the speedometer ,tachometer etc.. cause that is the only thing interior that works now in the dark.. the courtesy light works when I flip the headlight switch thing all the way to the top, and the ac/heater buttons light up indicating what setting is on (vents ,feet, defrost ect) but no other illumination is lit on the ac/heater or anything else, I did order the Ac Delco part from amazon.

:bash

The Central Control module determines the brightness of the Digital (LCD) Display and the back lighting for the the dash cluster, Tach, oil pressure, coolant temperature gauges etc..

When the headlight switch is Off, the CCM uses the ambient light sensor to determine LCD brightness.

When the headlight switch is On, the CCM uses the ambient light sensor and the head light dimmer switch
position to determine the LCD brightness and the back ground light brightness for the dash cluster Tach, oil temp. coolant temp gauges etc..

All of the incandescent lighting you refer to as being DEAD are controlled only by the dimmer switch and not the ambient light sensor. The position of the dimmer switch controls the Incandescent Driver Module which determines how much voltage the bulbs get (12 volts or less). The lights you see on the HVAC buttons and radio buttons are LED's. The brightness of the LED's as far as I can determine are controlled by the CCM which monitors the position of the dimmer switch. The signal voltage from the ambient light sensor is not used for the LED lights.
To the best of my knowledge that's how the circuit works.

If you were to follow the procedure In my prior post, that will tell you with 100% accuracy if the Module is
causing the problem.

 

[Jessica19699]

so ecss i am awaiting the ac delco part to come in so i can replace it but tonight i noticed also that my outside parking lights all the way around the car dont work either and the flood lights dont either,the headlights,backup lights and turn signals all work ..are the parking lights tied in with the interior illuminiation lights that i am getting ready to replace the part with? god i hope so ughhh

 

[ecss]

so ecss i am awaiting the ac delco part to come in so i can replace it but tonight i noticed also that my outside parking lights all the way around the car dont work either and the flood lights dont either,the headlights,backup lights and turn signals all work ..are the parking lights tied in with the interior illumination lights that i am getting ready to replace the part with? god i hope so ughhh

This is not good news. :ugh

You need to verify if the TAIL fuse is blown.

If the fuse is not blown you need to use a test light or volt meter and verify there is 12 volts at the TAIL
fuse which is hot all the time.

If the fuse is good, there could be a bad connection at the Headlight Switch connector or the electrical contact
in the Headlight switch is bad. To verify you need to gain access to the Headlight Switch and check for 12 volts on a Orange wire. That is the input voltage to the Headlight switch. Obviously 12 volts is not coming out of the Headlight switch via a Brown wire because of all the devices that use that 12 volts are not working. :L

This 12 volts is used by the headlight switch to power the Incandescent Power Module, front and rear parking
lamps, license plate lamp, fog lamps and cornering lamps.

The Headlight Switch uses a different set of contacts and power source to power the head lights.

 

[Jessica19699]

ecss thanks for the reply, so the tail lights and interior lights are a separate issue? also I just checked the tail light fuse and sure enough it was blown I did replace it but as I was literally putting the fuse in the spot a little spark popped in it and it blew the new fuse before I could even set it. the keys were not in the ignition and the headlights were not on, this is really starting to freak me out, what could cause this? is this a bad headlight switch like u said earlier or a grounding issue. If it is a bad headlight switch how hard are they to replace? thanks so much for all your help

 

[Jessica19699]

ecss I just reread your posting you say the tail light fuse spot stays hot all the time? so that could be why it sparked on me is there a certain way to replace new fuses like that? maybe disconnect the battery?

 

[ecss]

ecss I just reread your posting you say the tail light fuse spot stays hot all the time? so that could be why it sparked on me is there a certain way to replace new fuses like that? maybe disconnect the battery?

The fuse has power to it all the time but unless the headlight switch is turned to the Head or Park position,
there is no load on the fuse so it should not blow.

Since the fuse blew when you installed it, either the Headlight Switch is bad (something inside the switch is bad)
or the wire from the fuse to the Headlight Switch connector is shorted to ground. (Insulation worn off the wire and touching something that is grounded).

*************************************************************************
If you decide to mess with the Headlight Switch first disconnect the Negative battery terminal.
*************************************************************************

Gain access to the Headlight Switch and unplug the connector with a Orange wire.


*******************************
Reconnect the negative battery terminal.

With the connector unplugged if you install the new fuse and it blows that would indicate a wiring problem
from the Headlight Switch Orange wire to the fuse block.

If the fuse doesn't blow that would indicate the problem is the Headlight switch.

I'll go look at my 90 and see how hard it is to get to the back of the Headlight Switch. I've had it out
a long time ago and don't remember what needs to be removed to get the connector.

 

[Jessica19699]

ecss thanks again for the reply, let me know if you find the info pleas.so could u say if the headlight switch is bad maybe that is what is wrong with the illumination lights as well aren't they controlled off that as well with the brightness ,dimness ect.? also if the switch is possibly bad why do the headlights still work?

 

[ecss]

ecss thanks again for the reply, let me know if you find the info pleas.so could u say if the headlight switch is bad maybe that is what is wrong with the illumination lights as well aren't they controlled off that as well with the brightness ,dimness ect.? also if the switch is possibly bad why do the headlights still work?

The Headlights use a different set of contacts inside the Headlight switch and a different power source. (Not the Tail fuse).

Finding what is causing the fuse to blow will fix all of your problems. :L

From your new found symptoms (Blown Tail fuse) I'm pretty confident the Incandescent Driver Module
is not your problem. If Amazon hasn't shipped yet, cancel the order.

I'll post some pictures in a minute showing how to get access to the Headlight Switch.

 

[Jessica19699]

ecss awesome thanks again, amazon already shipped it but I wont install it until I make sure it isn't something else if it is I will send it back no big deal, also if you might know what part to order for the replacement part for the headlight switch that would be a great help as well, I will look forward to seeing your pics,me being a woman I am clueless to these kinds of things so thanks again for your help you are a life saver:L

 

[ecss]

ecss awesome thanks again, amazon already shipped it but I wont install it until I make sure it isn't something else if it is I will send it back no big deal, also if you might know what part to order for the replacement part for the headlight switch that would be a great help as well, I will look forward to seeing your pics,me being a woman I am clueless to these kinds of things so thanks again for your help you are a life saver:L

This is for a 90. Can't say for sure a 92 is the same.

The screws are easy to drop so be extra careful when you remove them. If you have a magnet with an
extension it will help to retrieve any screws or bolts that drop inside the dash area.

When you reinstall the two bolts holding the Headlight Switch use tape inside your nut driver or socket
to keep the bolts from dropping.

First pic shows the side panel on the driver side end of the dash.
Need to remove 3 phillip screws and the plastic panel comes off.



2nd picture shows the two phillip screws you need to remove from the black plastic bezel piece that surrounds the dash cluster. You only need to remove two of the screws. This will allow you to pull the bezel away to gain clearance to remove the two 9/32 bolts holding the right side of the Headlight Switch. You can use the tilt lever
to move the steering wheel up to get better access to the screws.



3rd picture shows the two 9/32 bolt hole location.



4th and 5th picture shows where two of the electrical plugs plug into the back of the headlight switch.
You only need to unplug the large plug that has the Orange wire in the connector.

Picture 4 shows the connector plug for the fog lamp switch which you don't need to remove unless you replace the switch. There is also a connector for the traction control switch. The picture shows the knub which keeps you from removing the connector plug. You use something flat and pry inward on the connector to clear the knub while you unplug the connector.



Picture 5 shows the connector plug for the larger connector and this is the plug with the Orange wire.
After you unplug this plug replace the TAIL fuse, reconnect the negative battery cable and see if the fuse blows. If it blows the problem is in the Orange wire. (Shorted somewhere from the connector plug to the fuse panel).

If the fuse does not blow the problem is in the Headlight Switch.



As for the headlight switch, don't quote me but I believe all headlight switches are the same from 92-96.
These switches had the traction control switch while 90-91 did not not have traction control.

I'm guessing the only difference between 92-96 head light switches is the color of the plastic cosmetic cover and the lettering are different colors between the 92-93 and 94-96 years.

It appears the switch is only sold as an assembly. (Switch and plastic cover).
92-93 are the same. Dark Gray cover with I think orange lettering (could be Yellow). 94-96 I think have a Black cover and White lettering.

You could take a chance and buy a 94-96 since it has a lower price. Unbolt the Headlight Switch and install it in your Dark Gray housing.

Here's a 92-93 which is exactly like yours.

Also I've attached a link for a 94-96 which I believe is the same switch with a different colored bezel.
Note these are used. New ones sell for over $200.00 ad

There is not a big demand for Headlight Switches so I would make a lower offer and if the seller says no,
no harm done.

Both listings are by the same seller.
----------------------------------------

92-93 $89.00 or Best Offer
http://www.ebay.com/itm/92-93-Corve...92|Model:Corvette&hash=item58c7fd1aeb&vxp=mtr

94-96 $63.00 or Best Offer

http://www.ebay.com/itm/94-96-Corve...758-/381312375592?hash=item58c7fd1b28&vxp=mtr

 

[Jessica19699]

ecss wow you really done your homework,thanks so much for all this info i really apreciate it.i will try this and hope to god it works,i will post again when i check this out may take me some time as i may get my bf or another friend to help me, thanks again really it is good guys like you that make this forum awesome,take care and i will be in touch soon

 

[Jessica19699]

ecss my boyfriend will be down tomorrow so we can check out the headlight switch, I did have another question well two more actually can or will a bad headlight switch leave a code on the ccm that I could check it with the jumper wire and see if it bad that way? also where is the high beam switch for the headlights, is it on the turn signal/wiper lever? thanks again and sorry to be a pain in the butt lol

 

[ecss]

There are some CCM diagnostics to diagnose the dimmer portion of the Headlight switch used to dim the incandescent and LED circuits.

As far as I know there are no CCM codes to detect a bad Headlight switch.

The Headlight switch has that dimmer lever which also has a position to turn on the interior lights.
You know that portion works. The dimmer portion to dim the back lighting you know does not work.
That portion of the switch needs 12 volts from the Tail fuse.

The high beam switch is bolted to the middle of the steering column (driver side of the column) by a nut and a bolt as shown in the picture below. The headlight high low beam dimmer switch is operated by a round medal rod that (Yellow arrow points to the rod) is activated when you pull the turn signal stalk forward.
The switch is shown in the picture with the red box around it.

If you were to remove the driver side hush panel and activate the High beam switch you can
physically see the rod move the High beam switch. That's where the click noise comes from.:L

If you ever remove the High Low beam switch make sure you tape the rod against the steering column so it can't move.
If that rod falls out of position you're in a heap of trouble.

 

[Jessica19699]

ok thanks again ecss I don't plan to remove or access the switch I was just curious if it was on the turn signal rod and if you activate the high beam by pulling the stick to you or pushing it out away from you, as for the ccm codes I just wanted to make sure there wasn't a way to see an error code before I access the switch I will repost in a few days to let you know what I find out with the switch