2002 Camry XLE - radio lighting problem

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Just bought a 2002 Camry XLE V6 (86.6k miles) with JLB Premium Sound Package from a dealer. Works great during the day, but no night time illumination.
Any suggestions on where to look for problems?

Don't know if related but previous owner had "A/C LIGHT IS BLINKING AND IS INOP" repaired at 75.1K miles.

Cannot talk with previous owner, but good maintenance records provided.


Am considering aftermarket NAV system if current audio system fails. Any comments?

[Brian R.]

Check out this site:
http://www.installdr.com/

There is probably a wire not connected correctly which provides lighting. The other possibility I can think of is that the head unit lighting died and needs to be replaced.

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Originally Posted by Brian R.

Check out this site:
http://www.installdr.com/

There is probably a wire not connected correctly which provides lighting. The other possibility I can think of is that the head unit lighting died and needs to be replaced.

It is definitely a wiring issue...
Radio is illuminated during daylight (LED & face plate)
When headlights turned on, radio lighting disappears (LED's remain), but other dash lighting OK.

Turning key to acc, radio lighting comes on.
Turning key further to on, radio & dash lights come on
Starting engine, both radio & dash lighting remain on.

At this point with headlights off, dimmer not engaged.
Turning on headlights, radio lighting disappears, dash lights respond to dimmer.

At no point are the buttons on the radio illuminated, only the face plate. Radio does not appear to be connected through dimmer circuit, so I am guessing that is where the break happened.

Now I am open to suggestions on how to fix the problem.?

[Brian R.]

Find out how to install the head unit and redo the wiring.

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Originally Posted by Brian R.

Find out how to install the head unit and redo the wiring.

Thanks...

I was able to locate "TURNING ON LIGHT SWITCH DOES NOT LIGHT UP NIGHT TIME ILLUMINATION OF RADIO RECEIVER" online from Chilton's in our local library.

Unfortunately for me, it takes a certain amount of expertise to understand what is written. I am in the learning phase. There are no pictures, ha.

I am guessing that since the dash lights work correctly, the open circuit is somewhere between the dimmer switch, through the radio and to ground. I am hopeful that a simple test light from connectors to ground should work.

But I still need to learn how to access the connectors and correctly identify the physical wire.

I am getting a bit long-of-tooth to be laying upside down on the front seat searching for the problem. Any idea the cost involved to have this professionally solved?

Thanks

[Brian R.]

Did you check out any information in the site linked in my first post?

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Looked at the website and it helped some...

My son (who can read electric schematics) developed a plan to test illumination circuit of the wiring harness to the radio. Told me we could isolate the problem to either wiring or radio.

Found a website that shows how to access radio wiring: http://www.gtacarkits.com/toyota_cam...06_car_kit.php

Local car dealer said they would cover 50% of labor and parts if radio faulty.

Since my son lives a couple of hours away and has a demanding job, I am on hold until we can get together for the test.


Just tested harness and found no power in illumination circuit (green wire) to radio. Radio 12v (blue/yellow) to ground (brown) tested OK, but green to brown with headlights on - nothing.

The wiring harness to radio appears in excellent shape with no obvious signs of distress.

Where would you suggest I look now? How do you test the dash illumination switch? Is it possible for it to function on the instrument cluster but fail on the radio?

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Is there an illustration showing wire colors (& position) for the pin connector to a Toyota A56820. I want to be sure that the green wire was the illumination circuit to my radio.

[landlocked]

Thanks for all the suggestions...

Isolated the lighting problem to the radio 'bulbs'.

Received some basic audio circuit training and was able to better understand where to test. Located the correct 'green' wire and it tested 12v to ground. Located the wire (white with green stripe) that was controlled by the 'rheostat'.

Voltmeter between wires showed voltage varied with rheostat. Concluded problem must be radio bulbs.

[Brian R.]

Good job! Thank you for the update.

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As a final comment to my lighting problem, I did learn that Toyota has a new way for the rheostat to function. In the past the rheostat varied the voltage by mechanically varying the resistance. In my car the voltage to each circuit is a constant 12v, but the ground is varied by the rheostat. My knowledgeable friend informed me that in my car the dash light dimmer switch 'pulses' to a varied ground; the longer the time between pulses, the lower the average voltage.
I think I am explaining it correctly. That information changes how you look for an open circuit.