IBM 4500R Hardware Maintenance Manual - Page 141

Bus fault messages Message Failure reading 12C device. Check devices on bus 0. Failure reading 12C device. Check devices on bus 1. Failure reading 12C device. Check devices on bus 2. Failure reading 12C device. Check devices on bus 3. Failure reading 12C device. Check devices on bus 4. Action 1. Replace system board 1. Reseat power Supply 2. Replace power supply 3. Replace power supply backplane 4. Replace system board 1. Replace DASD backplane 2. Replace system board 1. Replace system board 1. Replace DIMM 2. Replace system board Undetermined problems You are here because the diagnostic tests did not identify the failure, the Devices List is incorrect, or the system is inoperative. Note: A corrupt CMOS can cause undetermined problems. Check the LEDs on all the power supplies, see"Power supply LED errors" on page 121. If the LEDs indicate the power supplies are working correctly, return here and do the following: 1. Power-off the computer. 2. Be sure the system is cabled correctly. 3. Remove or disconnect the following (one at a time) until you find the failure (power-on the computer and reconfigure each time). Any external devices Surge suppressor device (on the computer) Modem, printer, mouse, or non-IBM devices Each adapter Drives Memory-Modules (Minimum requirement = 128 MB (4x128 MB DIMMs)) Note: Minimum operating requirements are: a. 1 Power Supply b. Power Backplane c. System Board d. 1 Microprocessor and VRM e. 1 Terminator Card f. Memory Module (with a minimum of 1 bank of 128 MB DIMMs) 4. Power-on the computer. If the problem remains, suspect the following FRUs in the order listed: Power Supply Power Backplane Symptom-to-FRU index 133