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Symptoms Chart
Symptom Charts
Follow steps in the order indicated below. If an action resolves the issue, retest system to verify.
Startup and Power
No Power, Dead Unit
Unlikely cause: speakers
Quick Check
| Symptoms | Quick Check |
|---|---|
| No Power, Dead Unit • No power • No fan spin • No startup chime • No image on external display • No hard drive or optical drive activity • Caps Lock LED on wired keyboard doesn't light when pressed. | 1. Verify power source. 2. Verify power cable. 3. Listen closely for signs of activity from system including: rotating fans, hard drive or optical drive activity, startup chime, etc. |
Table Caption: This table lists symptoms of a dead computer unit and provides quick troubleshooting steps to verify power and listen for system activity.
Deep Dive
| Check | Result | Action | Code |
|---|---|---|---|
| 1. Power ON system. Verify if there is any indication that the system has powered up (fan rotation, hard drive or optical drive noise, backlight turns on). | Yes | The symptom is powering up. Go to Won't Start Up symptom flow. | |
| No | Go to step 2. | ||
| 2. Locate diagnostic LEDs in bottom case vents. Plug AC cord into system. Verify if diagnostic LED #1 turns ON. You may alternately check for presence of a 12V DC signal between pin 4 and pin 1 of logic board. | Yes | Standby power voltage being supplied by power supply. Go to step 3. | |
| No | Replace power supply. |
Table Caption: This table outlines a troubleshooting process for a system that may not be powering on. It guides the user through checks for power indication and the presence of standby power, leading to either a further troubleshooting step or a recommended component replacement.
| 3. Press power button while monitoring diagnostic LEDs. Verify if LED #2 turns ON and remain ON after pressing the power button.You may alternately check for a power request signal between pin 12 and pin 1 of logic board. | Yes | Power supply functioning and logic board detects supply voltages. Go to Won't Start Up symptom flow. | |
|---|---|---|---|
| No | Go to step 4. | ||
| 4. Disconnect AC cable then remove power supply and carefully inspect connectors between AC inlet and power supply, then DC connectors and cables between power supply and logic board, for damage or poor connections. | Yes | Replace damaged part. | P16 |
| No | Go to step 5. | ||
| 5. Inspect power button and verify if it is properly connected to the logic board. | Yes | Go to step 6. | |
| No | Reconnect power button. | ||
| 6. Disconnect power button from logic board. Inspect cable and connector for damage.Verify continuity between the two pins of power button when it is pressed. | Yes | Power button is functioning correctly. Reconnect power button to logic board and go to step 7. | |
| No | Power button faulty. Replace rear housing (which includes power button). | X14 | |
| 7. Press power button and Verify if system turns ON.You may alternately check for presence of a 12V DC signal between pin 1 1 and pin 1 of logic board when power button is pressed. | Yes | Power supply functioning. If system still won't boot, go to Won't Start Up symptom flow. | |
| No | Replace DC power cable. Go to step 8. | X03 | |
| 8. Press power button and verify if system turns ON. | Yes | Issue solved with replaced DC power cable. | |
| No | Replace power supply. Go to step 9. | P01 | |
| 9. Press power button and verify if system turns ON. | Yes | Issue solved with replaced power supply. | |
| No | Reinstall power supply and replace logic board. | M01 |
Table Caption: This troubleshooting table outlines steps to diagnose a "Won't Start Up" issue, starting with checking power supply and logic board responses via LEDs and voltage signals, then progressing to inspecting physical connections, the power button, and finally the DC power cable and power supply itself, with specific part replacement recommendations for certain failures.
Note: If No Power symptom persists after all steps have been followed use minimum configuration troubleshooting to proceed. Try disconnecting hard drive, optical drive, AirPort, Bluetooth, and SD card modules to determine if one of them is preventing the power supply from functioning.
Won't Start Up
Quick Check
| Symptoms | Quick Check |
|---|---|
| Won't Start Up • No startup chime. • Error tones during startup. • Grey screen with fan noise, or other noise. • Will not progress beyond Apple logo or spinning gear. | 1. Isolate OS by starting up from original install media for this computer, from a same-model computer in Target Disk Mode, or from a compatible known-good OS on an external drive. Both AirPort and Bluetooth services are available when booted from the Install disk. 2. Reset SMC and PRAM to clear any stored, corrupted information. 3. Start up in Safe Mode by holding shift key down during startup to load only required kernel extensions and disable all startup and login items. See kBase #HT1564:Mac OS X:What is Safe Boot, Safe Mode? 4. If system generates error tones there may be an issue with the SDRAM. See kBase #HT2341: Intel- based Mac: Power On Self Test RAM error codes 5. Identifying when in the startup process the computer hangs can help isolate the issue. See kBase #HT2674: Intel-based Mac: Startup sequence and error codes, symbols for information on the Macintosh startup sequence, and error codes and symbols used. |
Table Caption: This table provides troubleshooting steps for a Mac computer that won't start up, covering initial checks, memory issues, and identifying specific startup errors.
Deep Dive
| Check | Result | Action | Code |
|---|---|---|---|
| 1. Boot computer to Apple Hardware Test on the internal hard drive or an inserted Install DVD by holding down the D key at startup. Verify if system boots up from any of these volumes. | Yes | Run the extended tests and proceed with results. If AHT passes or boots with a memory error, go to step 2. | |
| No | Go to step 2. | ||
| 2. Remove installed SDRAM, and test with known-good SDRAM. Verify if computer starts up properly now. | Yes | SDRAM issue. Reinstall one of user's SDRAM modules and retest. Proceed one by one to find the faulty SDRAM module, and replace it. | X02 |
| No | Go to step 3. |
**Table Caption: This table outlines a troubleshooting process for a computer, starting with
