96eb96
Explorer Addict
- Joined
- October 20, 2004
- Messages
- 3,530
- Reaction score
- 329
- City, State
- Albany, NY
- Year, Model & Trim Level
- 96 EB V6 OHV 4WD
Not the worst thing in the world, but the radio lights went out. Then I learned about our interior lighting arrangement.
The dimming switch isn't as simple as it seems. It outputs PWM(pulse width modulated) DC to some devices. I believe there is a straight variable DC output as well. Some devices use this voltage directly for illumination, while some just use it to control the intensity of the light.
The Radio and rear controls use this signal for illumination. The radio does not have any bulbs. There is a paper thin sheet of space age material that lights up in the pattern of the buttons! It is like an illuminated Printed board. The electronics switch banks of lights depending on the function you use.
Interestingly, the compass uses this PWM signal to reduce the intensity of the LCD, as does the climate control module and message center. So even though there is an illumination input, you will still have use of those devices.
So...my radio and rear controls have no light, so I measure voltage at circuit 19..PWM....find .005 volts. Supposed to be 3-11. Then I'm looking for shorts, opens, whatever, pulling all the gadgets on this circuit, even took apart the radio face. Then after 3 hours of troubleshooting I realize that the dimmer has no effect on the compass or message center!!!!
I play with the dimmer wheel (its nighttime) and I see a momentary change in the compass and messagecenter intensity, and my voltmeter pops with some voltage. So the cat is out of the bag now...
So the next step is to change that unit....
Hopefully this will help someone in the future!
The dimming switch isn't as simple as it seems. It outputs PWM(pulse width modulated) DC to some devices. I believe there is a straight variable DC output as well. Some devices use this voltage directly for illumination, while some just use it to control the intensity of the light.
The Radio and rear controls use this signal for illumination. The radio does not have any bulbs. There is a paper thin sheet of space age material that lights up in the pattern of the buttons! It is like an illuminated Printed board. The electronics switch banks of lights depending on the function you use.
Interestingly, the compass uses this PWM signal to reduce the intensity of the LCD, as does the climate control module and message center. So even though there is an illumination input, you will still have use of those devices.
So...my radio and rear controls have no light, so I measure voltage at circuit 19..PWM....find .005 volts. Supposed to be 3-11. Then I'm looking for shorts, opens, whatever, pulling all the gadgets on this circuit, even took apart the radio face. Then after 3 hours of troubleshooting I realize that the dimmer has no effect on the compass or message center!!!!
I play with the dimmer wheel (its nighttime) and I see a momentary change in the compass and messagecenter intensity, and my voltmeter pops with some voltage. So the cat is out of the bag now...
So the next step is to change that unit....
Hopefully this will help someone in the future!
