From Tim Clarke
   If it's an actual read error on the IML boot record and it couldn't recover (it tries 20 different 5-sector records for a Type-3) then the area at the "end" of the drive's capacity is suspect. Backup operational partitions and do an LLFormat from Advanced Diagnostics without clearing the "grown defect list". Then Restore System Partition and then verify IML is O.K. before reloading operational partitions. 

   You are here because the system detects an Initial Machine Load (IML) problem or an Initial Program Load (IPL) problem. You can correct most of these errors without replacing any FRUs. IML/IPL problems are associated with the following: 
    An I999XXXX error is displayed. 
    Computer powers-on without POST error, but operating system does not work. 
    The system starts up in BASIC. 

IML and IPL errors can be caused by any of the following conditions: 
    Invalid selectable drive startup sequence (default drive not in startup sequence) 
    Operating system not found 
    IML code not found 
    Related hardware failure (SCSI adapter, hard disk, SCSI cable) 
    Unrelated hardware failure (misleading error due to problem on SCSI Bus). 

Checking Startup Sequence and Hard Disk Drive
1. Start computer from RefDisk and select Set Features from Main Menu. 
2. Select Set Startup Sequence and see if default HD (usually ID6) is in startup 
    sequence. If you get an error, follow instructions on the screen, then return here. 
3. If the default drive is in startup sequence, exit from screen and Main Menu, then
    go to step 5. If default drive is not in startup sequence, follow instructions on the
    screen, then continue with step 4. 
4. Remove RefDisk, power-off computer, then power-on computer. If the "F1" (Insert
    Diskette) icon appears on screen, this means no operating system was found. Go 
    to step 5. If the "Not OK" icon appears, this means that the system cannot access
   the System Partition. Try updating the system programs.
5. Either install an operating system on a device that is in the startup sequence, or 
     change the startup sequence to include a device that has an operating system, then 
     power-on the computer, check for the normal power-up sequence and then run the 
     advanced diagnostic tests. If the problem still exists, suspect the SCSI controller,
    then the hard disk drive.

NOTES:
Password Jumper: 
   t may be necessary to move the power-on password jumper (J16-8595 or J10 - 8590) to enable an IML to the reference diskette in drive A. Moving this jumper forces the stage 1 POST routine to branch to the diskette, rather than attempt to load stage 2 from the Fixed disk system partition. (A reference diskette must be present in the a: drive)
     The Stage 2 POST code on the reference diskette is identical to the code loaded onto the system partition, Moving this jumper sets all default values, except ASCII terminal mode. It should be further noted, that moving the Power-On password jumper is effective for only 1 Power-On cycle because stage 1 POST tracks (records) the positon of the jumper each time it is run.

ASCII Terminal Mode: 
   If ASCII terminal mode is set (96-8N1, Visible in information panell), the battery voltage must be removed from the planar to reset it. (Slide stiff paper under the battery clip for approx 10 to 15 minutes).
   ASCII terminal mode will be automatically set by stage 1 POST if there is no primary video adapter detected (XGA adapter is missing from the system).

I999xxxx Error Codes

I999 00X5	Reference Diskette recovery prevented  - Power Off the computer  - Toggle Password Override Jumper - Power On the computer
Restore the System Partition for these errors
I999 001X  I999 002X  I999 003X  I999 004X  I999 006X  I999 007X  I999 009X    X can be any number	No valid disk IML record found on HD  Disk IML record load (read) error  Disk IML record incompatible w/planar  Disk IML record incompatible w.processor board  Disk Stage 2 image load read error  Disk Stage 2 checksum (read) error  System board BIOS newer than Disk IML Partition  The actions for these errors are only valid when running the system from the hard disk:  - Restore the System Partition
Boot with a valid reference diskette for these errors
I999 00X1  I999 00X2  I999 00X3  I999 00X4  I999 00X5 I999 00X6  I999 00X7  I999 00X9	Invalid diskette IML record  Diskette IML record load (read) error  Diskette IML record incompatible w/system board  Diskette IML record incompatible w/complex  Diskette IML Recovery prevented    Power-Down, Toggle J10 (90)  J16 (95), Power-Up Diskette Stage 2 IML read error  Diskette Stage 2 IML checksum error  System board BIOS newer than Diskette BIOS  The actions for these errors are only valid when running the system from System Diskette:  - Restart computer from Refdisk - If same error appears, try new Refdisk
I999 0053, I999 0054  I999 0056, I999 0057  I999 0059, I999 0063  I999 0067, I999 0069	The actions for these errors are only valid when running the system from System Diskette:  - Restart computer from Refdisk  - If same error appears, try new Refdisk
I999 0301	No bootable device found, HD or floppy  This may be a hardware failure Check:  - Cabling  - Termination - Adapter / Controller  - Hard drive
I999 0302	Invalid disk boot record (missing OS)  - Install an operating system  - check for a valid startup sequence  - check presence of all devices listed in startup- sequence
I999 0303	System Partition boot failure  - Restore System Partition
I999 0304	No bootable device found with ASCII-console  Probably no operation system installed  - Install operation system  - Check selectable startup sequence if it contains the default drive
I999 0305	No startable device found  Probably no operation system installed  - Install operation system  - Check selectable startup sequence if it contains the default drive
I999 0306	Invalid startup.  - Trying to start from CD-ROM drive  - Restart computer from a startable Diskette or HD.
I999 0401  (Fatal)	Unauthorized Access  Clear power-on Password before replacing parts !  - Replace Planar or Processor board  (Whichever contains the ROM)
I999 0402   (Fatal) I999 0403   (Fatal)	- Replace Systemboard or complex  (Whichever contains the ROM)
I999 0600   (Fatal) I999 0607   (Fatal) I999 0609   (Fatal)	IBM Overlay errors  Restore System Partition
I999 80XX	ThinkPad system partition  1. Reseat HD. Check Startup Sequence  2. Hard Disk Drive  3. System Board

Usually Fatal I999xxx Errors
The following errors normally require processor FRU replacement:-
I9990401 - Unauthorised access.
I9990402 - Missing ROM IBM Copyright notice
I9990403 - Non IBM IML routine
I9990600 - IML Overlay Logistics Error
I9990607 - IML Overlay Checksum Error
I9990609 - IML Overlay ID Error