stands for Apple Service Diagnostics 3S159 . It is a version of the diagnostic software developed by Apple Inc. designed specifically to run on the Mac Pro (Late 2013) models.
What specific or error codes your Mac Pro is throwing?
The "3S" in the part number may denote a specific circuit topology. Verify using a multimeter in diode test mode before installing a used unit.
It does not appear in:
When deploying ASD 3S159 on certain sub-configurations of the Late 2013 Mac Pro, technicians occasionally encounter false failures related to or missing display backlight communication lines (since the Mac Pro does not feature an integrated internal panel). If your hardware setup triggers persistent, non-applicable errors in these categories, you should manually uncheck those specific sub-tests in the configuration panel before running the full automated diagnostic routine.
If you are an authorized service provider, you can often automate tests within the ASD environment. ASD OS Mode macOS environment
: Extensively stress-tests the 4-channel DDR3 ECC RAM slots to verify error-correcting functionality and trace failing DIMMs. asd 3s159
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: Users can choose to run "Standard" tests or "Interactive" tests which require manual input (like checking the front LED or audio jacks). ⚠️ Important Considerations
: Early diagnosis is critical—often identifiable by age 2 or 3—but traditional clinical assessments are time-consuming and expensive. stands for Apple Service Diagnostics 3S159
If a sensor misreads a high temperature, the Intel Xeon chip will drop its clock speed to a crawl. ASD can verify if the throttling is firmware-driven or due to physical component failure. How Technicians Use ASD 3S159
Each Mac generation required a specific version of ASD tailored to its precise EFI architecture and sensor schematic. According to the LogiWiki ASD Compatibility Matrix and IFIXIT4U Service Reference Records , version is the dedicated build created to handle the distinct dual-GPU system architecture of the Late 2013 Mac Pro. ASD vs. Apple Hardware Test (AHT)
Unlike consumer utilities like Apple Hardware Test (AHT) or Apple Diagnostics, which only check for basic functional responses, ASD executes exhaustive technical test routines. It interacts directly with the Mac's system firmware, logic board controllers, and hardware registers. What specific or error codes your Mac Pro is throwing
This is a consumer-grade utility built directly into the Mac's firmware or recovery partition. It provides basic high-level feedback, such as standard error codes, but cannot pinpoint specific IC failures or run continuous loop stress tests.