Skip to main content

1.6, 1.8, or 2 GHz G5 processor

130 Questions View all

LED 3 is not lighting up

Hello. My girlfriend bought this Mac from a local technical college resale shop. We used it for a month then she bought a newer, bigger model. She traded this model to my repair shop for a iBook G4. We had it in my shop for a month, worked fine. One day we got a gray screen and it made a really weird continuous beep sound. I shut it down, took it into my shop repair station and took it apart. I took the back panel off, plugged in power cord, mouse and keyboard. I used a screwdriver to connect the power switch contacts. The front light turns on, no fans, no chime. LED's 1 and 2 light up, but not 3. Does this mean the video chip is bad? Or could it be the LCD or Inverter? Thanks in advance for help.

Answered! View the answer I have this problem too

Is this a good question?

Score -1
Add a comment

1 Answer

Chosen Solution

LED 1 indicates that trickle voltage from the power supply has been detected. This LED will be ON when the computer is turned off and your power supply is working correctly.

LED 2 indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.

LED 3 indicates that the computer and the LCD display are communicating. This LED will be ON when the computer is turned on and video signal is being generated.

LED 4 lights only if the computer detects an over-temperature condition. This LED will be OFF when the computer is turned on and running at the correct temperature.

Hook it up to an external monitor to see if the GPU is generating a signal. Examine the capacitors for swelling and/or corrosion.

Was this answer helpful?

Score 3


I saw that you posted this on another thread about this topic. I understand that since 3 is not on that something is wrong video wise. I unfortunately do not have the adapter to go from the mini-dvi to vga/dvi, etc. I may be able to convince the owner to let me buy one from the apple store tomorrow. But really, with no #3 light on, and no fans going, it's gotta be the video card/chip right?


Really check the caps! If you don't want to mess with it, just send it here, call and tell them you're a dealer for better pricing:


There seems to be about 14 bulging caps all around the board, out of about 20 caps, which seems like a really high number. I guess they could be the problem, and it would be cheap to replace, it's just that I haven't had a lot of practice de-soldering and re-soldering caps on boards.


Replacing the caps is a real PITA, I don't do it anymore.

I had these folks in Utah repair a couple of boards for me last month but at half the price they are now quoting (I'll bargain when I send more). Here's their eBay ad:


Add a comment

Add your answer

William Miller will be eternally grateful.
View Statistics:

Past 24 Hours: 0

Past 7 Days: 0

Past 30 Days: 0

All Time: 1,877