Power problems

• Related tasks
• Cannot power on system unit
  Perform this procedure until you correct the problem and you can power on the system.
• Cannot power off system or SPCN-controlled I/O expansion unit
  Use this procedure to analyze a failure of the normal command and control panel procedures to power off the system unit or an SPCN-controlled I/O expansion unit.
• Cannot power on SPCN-controlled I/O expansion unit
  You are here because an SPCN-controlled I/O expansion unit cannot be powered on, and might be displaying a 1xxx-C62E reference code.

Cannot power on system unit

Please see Power isolation procedures for important safety information before continuing with this procedure.

1. Attempt to power on the system (see Powering on and powering off). Does the system power on, and is the system power status indicator light on continuously?
   Note:
   The system power status indicator blinks at the slower rate (one blink per two seconds) while powered off, and at the faster rate (one blink per second) during a normal power-on sequence.
   • No: Continue with the next step.
   • Yes: Go to step 13.
2. Are there any characters displayed on the control panel (a scrolling dot may be visible as a character)?
   • No: Continue with the next step.
   • Yes: Go to step 5.
3. Are the mainline ac power cables from the power supply, power distribution unit, or external uninterruptible power supply (UPS) to the customer's ac power outlet connected and seated correctly at both ends?
   • Yes: Continue with the next step.
   • No: Connect the mainline ac power cables correctly at both ends and go to step 1.
4. Perform the following:
   1. Verify that the UPS is powered on (if it is installed). If the UPS will not power on, follow the service procedures for the UPS to ensure proper line voltage and UPS operation.
   2. Disconnect the mainline ac power cable or ac power jumper cable from the system's ac power connector at the system.
   3. Use a multimeter to measure the ac voltage at the system end of the mainline ac power cable or ac power jumper cable.
      Note:
      Some system models have more than one mainline ac power cable or ac power jumper cable. For these models, disconnect all the mainline ac power cables or ac power jumper cables and measure the ac voltage at each cable before continuing with the next step.

      Is the ac voltage from 200 V ac to 240 V ac, or from 100 V ac to 127 V ac?

      • No: Go to step 8.
      • Yes: Continue with the next step.
5. Perform the following:
   1. Disconnect the mainline ac power cable(s) from the power outlet.
   2. Exchange the system unit control panel (Un-D1) (see Physical Locations).
   3. Reconnect the mainline ac power cables to the power outlet.
   4. Attempt to power on the system.

   Does the system power on?

   • No: Continue with the next step.
   • Yes: The system unit control panel was the failing item. This ends the procedure.
6. Perform the following:
   1. Disconnect the mainline ac power cable(s) from the power outlet.
   2. Exchange the power supply or supplies (Un-E1, Un-E2) (see Physical Locations).
   3. Reconnect the mainline ac power cables to the power outlet.
   4. Attempt to power on the system.

   Does the system power on?

   • No: Continue with the next step.
   • Yes: The power supply was the failing item. This ends the procedure.
7. Perform the following:
   1. Disconnect the mainline ac power cable(s).
   2. Replace the system backplane (Un-P1) (see Physical Locations).
   3. Reconnect the mainline ac power cables to the power outlet.
   4. Attempt to power on the system.

   Does the system power on?

   • No: Continue with the next step.
   • Yes: The service processor or the system backplane was the failing item. This ends the procedure.
8. Are you working on a system unit with a power distribution unit with tripped breakers?
   • No: Continue with the next step.
   • Yes: Perform the following:
     1. Reset the tripped power distribution breaker.
     2. Verify that the removable ac power cable is not the problem. Replace the cord, as installed, if it is defective.
     3. If the breaker continues to trip, install a new power supply (as installed) in each location until the defective one is found. This ends the procedure.
9. Does the system have an external UPS installed?
   • Yes: Continue with the next step.
   • No: Go to step 11.
10. Use a multimeter to measure the ac voltage at the external UPS outlets. Is the ac voltage from 200 V ac to 240 V or from 100 V ac to 127 V ac?
    • No: The UPS needs service. For 9910 type UPS, call IBM^(R) Service Support. For all other UPS types, have the customer call the UPS provider. In the meantime, go to step 12 to bypass the UPS.
    • Yes: Exchange the ac power cable, as installed (see DUMMY PAGE FOR Part information). This ends the procedure.
11. Perform the following:
    1. Disconnect the mainline ac power cable from the customer's ac power outlet.
    2. Use a multimeter to measure the ac voltage at the customer's ac power outlet.
       Note:
       Some system models have more than one mainline ac power cable. For these models, disconnect all the mainline ac power cables and measure the ac voltage at all ac power outlets before continuing with this step.

       Is the ac voltage from 200 V ac to 240 V ac or from 100 V ac to 127 V ac?

       • Yes: Exchange the mainline ac power cable. See the DUMMY PAGE FOR Part information. Then go to step 1.
       • No: Inform the customer that the ac voltage at the power outlet is not correct. When the ac voltage at the power outlet is correct, reconnect the mainline ac power cables to the power outlet. This ends the procedure.
12. Perform the following to bypass the UPS unit:
    1. Power off your system and the UPS unit.
    2. Remove the signal cable used between the UPS and the system.
    3. Remove any power jumper cords used between the UPS and the attached devices.
    4. Remove the country or region specific power cord used from the UPS to the wall outlet.
    5. Use the correct power cord (the original country or region specific power cord shipped with your system) and connect it to the power inlet on the system. Plug the other end of this cord into a compatible wall outlet.
    6. Attempt to power on the system.

    Does the power-on standby sequence complete successfully?

    • Yes: Go to Verifying a repair.This ends the procedure.
    • No: Go to step 5.
13. Display the selected IPL mode on the system unit control panel. See 'IPL information' in Progress Codes, SA76-0093. Is the selected mode the same mode that the customer was using when the power-on failure occurred?
    • No: Go to step 15.
    • Yes: Continue with the next step.
14. Is a function 11 reference code displayed on the system unit control panel?
    • No: Go to step 16.
    • Yes: Return to Starting a Service Call. This ends the procedure.
15. Perform the following:
    1. Power off the system.
    2. Select the mode on the system unit control panel that the customer was using when the power-on failure occurred.
    3. Attempt to power on the system.

    Does the system power on?

    • Yes: Continue with the next step.
    • No: Exchange the system unit control panel (Un-D1) (see Physical Locations).This ends the procedure.
16. Continue the IPL. Does the IPL complete successfully?
    • Yes: This ends the procedure.
    • No: Return to Starting a Service Call. This ends the procedure.

Cannot power off system or SPCN-controlled I/O expansion unit

Please see Power isolation procedures for important safety information before continuing with this procedure.

1. Is the power off problem on the system unit?
   • No: Continue with the next step.
   • Yes: Go to step 3.
2. Ensure that the SPCN cables that connect the units are connected and seated correctly at both ends. Does the I/O unit power off, and is the power indicator light blinking slowly?
   • Yes: This ends the procedure.
   • No: Go to step 7.
3. Attempt to power off the system. Does the system unit power off, and is the power indicator light blinking slowly?
   • No: Continue with the next step.
   • Yes: The system is not responding to normal power off procedures which could indicate a Licensed Internal Code problem. Contact your next level of support.This ends the procedure.
4. Attempt to power off the system using ASMI. Does the system power off?
   • Yes: The system is not responding to normal power off procedures which could indicate a Licensed Internal Code problem. Contact your next level of support.This ends the procedure.
   • No: Continue with the next step.
5. Attempt to power off the system using the control panel power button. Does the system power off?
   • Yes: Continue with the next step.
   • No: Go to step 10.
6. Is there a reference code logged in either ASMI, the control panel or the HMC that indicates a power problem?
   • Yes: Perform problem analysis for the reference code in the log.This ends the procedure.
   • No: Contact your next level of support. This ends the procedure.
7. Is the I/O expansion unit that will not power off part of a shared I/O tower loop?
   • Yes: Go to step 9.
   • No: Continue with the next step.
8. Attempt to power off the I/O expansion unit. Were you able to power off the expansion unit?
   • Yes: This ends the procedure.
   • No: Go to step 10.
9. The unit will only power off under certain conditions:
   • If the unit is in private mode, it should power off with the system unit that is connected by the SPCN frame-to-frame cable.
   • If the unit is in switchable mode, it should power off if the "owning" system is powered off or is powering off, and the system unit that is connected by the SPCN frame-to-frame cable is powered off or is powering off.

   Does the I/O expansion unit power off?

   • No: Continue with the next step.
   • Yes: This ends the procedure.
10. Ensure there are no jobs running on the system or partition, and verify that an uninterruptible power supply (UPS) is not powering the system or I/O expansion unit. Then continue with the next step.
11. Perform the following:
    1. Remove the system or I/O expansion unit ac power cord from the external UPS or, if an external UPS is not installed, from the customer's ac power outlet. If the system or I/O expansion unit has more than one ac line cord, disconnect all the ac line cords.
    2. Exchange the following FRUs one at a time (see Physical Locations and DUMMY PAGE FOR Part information).

       If the system unit is failing:

       1. Power supply (Un-E1 or Un-E2)
       2. System backplane (Un-P1)
       3. System control panel (Un-D1)

       If an I/O expansion unit is failing:

       1. Each power supply
       2. I/O backplane
       3. I/O backplane in the unit preceding the unit that will not power off
       4. SPCN frame-to-frame cable

       This ends the procedure.

12. A power supply might be the failing item.
    Attention: When replacing a redundant power supply, a 1xxx 1504, 1514, 1524, or 1534 reference code may surface in the error log. If you just removed and replaced the power supply in the location associated with this reference code, and the power supply came ready after the install, disregard this reference code. If you had not previously removed and replaced a power supply, the power supply did not come ready after installation, or there are repeated fan fault errors after the power supply replacement, continue to follow these steps.

    Is the reference code 1xxx-15xx?

    • No:Continue withe the next step.
    • Yes:Perform the following:
    1. Find the unit reference code in one of the following tables to determine the failing power supply.
    2. Ensure that the power cables are properly connected and seated.
    3. Is the reference code 1xxx-1500, 1510, 1520, or 1530 and is the failing unit configured with a redundant power supply option (or dual line cord feature)?
       • Yes:Perform PWR1911 before replacing parts.
       • No:Continue with step 12d
    4. Refer to Physical Locations to determine the location and part number of the failing item.
    5. Replace the failing power supply (see the following tables to determine which power supply to replace).
    6. Perform the following if the new power supply does not fix the problem:
       1. Reinstall the original power supply.
       2. Try the new power supply in each of the other positions listed in the table.
       3. If the problem still is not fixed, reinstall the original power supply and go to the next FRU in the list.
       4. For reference codes 1xxx-1500, 1510, 1520, and 1530, exchange the power distribution backplane if a problem persists after replacing the power supply.

    Table 11. Model HV4

    Unit Reference Code	Power Supply
    1510, 1511, 1512, 1513, 1514, 7110	E1
    1520, 1521, 1522, 1523, 1524, 7120	E2

    Table 12. Model HV4 (Quiet office)

    Unit Reference Code	Power Supply
    1510, 1511, 1512, 1513, 1514, 7110	E1

    Attention: For reference codes 1500, 1510, 1520, and 1530, perform PWR1911 before replacing parts.

    Table 13. 5088, 0588 expansion units

    Unit Reference Code	Power Supply
    1510, 1511, 1512, 1513, 1514, 1516	P02
    1520, 1521, 1522, 1523, 1524, 1526	P01

    Attention: On a dual line cord system, for reference codes 1500, 1510, 1520, and 1530, perform PWR1911 before replacing parts. On a single line cord system, check the ac jumper to the power supply before replacing parts.

    Table 14. 5094, 5294 I/O expansion units (single line cord)

    Unit Reference Code	Power Supply
    1510, 1511, 1512, 1513, 1514, 1516	P01
    1520, 1521, 1522, 1523, 1524, 1526	P02
    1530, 1531, 1532, 1533, 1534, 1536	P03

    Attention: On a dual line cord system, for reference codes 1500, 1510, 1520, and 1530, perform PWR1911 before replacing parts. On a single line cord system, check the ac jumper to the power supply before replacing parts.
    Attention: For 5094, 5294 expansion units, do not install power supplies P00 and P01 ac jumper cables on the same ac input module.

    Table 15. 5094, 5294 I/O expansion units (dual line cord)

    Unit Reference Code	Power Supply
    1500, 1501, 1502, 1503	P00
    1510, 1511, 1512, 1513, 1514, 1516	P01
    1520, 1521, 1522, 1523, 1524, 1526	P02
    1530, 1531, 1532, 1533	P03

    Table 16. 5095, 0595, 5790, 7311-D11, 7311-D20, 7314-G30 expansion units

    Unit Reference Code	Power Supply
    1510, 1511, 1512, 1513, 1514, 1516, 1517	P01/E1
    1520, 1521, 1522, 1523, 1524, 1526, 1527	P02/E2

    This ends the procedure.
13. Is the reference code 1xxx-2600, 2603, 2605, or 2606?
    • No: Continue with the next step.
    • Yes: Perform the following:
    1. Refer to Physical Locations to determine the location and part number of the failing item.
    2. Replace the failing power supply.
    3. Perform the following if the new power supply does not fix the problem:
       1. Reinstall the original power supply.
       2. Try the new power supply in each of the other positions listed in the table.
       3. If the problem still is not fixed, reinstall the original power supply and go to the next FRU in the list.
       Attention: Do not install power supplies P00 and P01 ac jumper cables on the same ac input module.

       Table 17. Failing power supplies

       System or Feature Code	Failing Power Supply
       Model HV4	Un-E1, Un-E2
       5094, 5294 (single line cord)	P01, P02, P03
       5094, 5294 (dual line cord)	P00, P01, P02, P03
       5088, 0588	P02, P01
       5095, 0595	P01, P02
       5790, 7311-D11, 7311-D20, 7314-G30	E1, E2

       This ends the procedure.
14. Is the reference code 1xxx 8455 or 8456?
    • No: Return to Starting a Service Call. This ends the procedure.
    • Yes: One of the power supplies is missing, and must be installed. Use the following table to determine which power supply is missing, and install the power supply ( see Physical Locations to determine the part number and exchange procedure).

    Table 18. Missing power supplies

    Reference Code	Missing Power Supply
    1xxx 8455	Un-E1
    1xxx 8456	Un-E2

    This ends the procedure.

Cannot power on SPCN-controlled I/O expansion unit

Please see Power isolation procedures for important safety information before continuing with this procedure.

1. Power on the system.
2. Starting from SPCN 0 or SPCN 1 on the system unit (see Physical Locations), go to the first unit in the SPCN frame-to-frame cable sequence that does not power on. Is the Data display background light on, or is the power-on LED blinking, or are there any characters displayed on the I/O expansion unit display panel?
   Note:
   The background light is a dim (yellow) light in the Data area of the display panel.
   • Yes: Go to step 12.
   • No: Continue with the next step.
3. Use a multimeter to measure the ac voltage at the customer's ac power outlet.

   Is the ac voltage from 200 V ac to 240 V ac, or from 100 V ac to 127 V ac?

   • Yes: Continue with the next step.
   • No: Inform the customer that the ac voltage at the power outlet is not correct.

     This ends the procedure.

4. Is the mainline ac power cable from the ac module, power supply, or power distribution unit to the customer's ac power outlet connected and seated correctly at both ends?
   • Yes: Continue with the next step.
   • No: Connect the mainline ac power cable correctly at both ends.

     This ends the procedure.

5. Perform the following:
   1. Disconnect the mainline ac power cable from the ac module, power supply, or power distribution unit.
   2. Use a multimeter to measure the ac voltage at the ac module, power supply, or power distribution unit end of the mainline ac power cable.

   Is the ac voltage from 200 V ac to 240 V ac, or from 100 V ac to 127 V ac?

   • No: Continue with the next step.
   • Yes: Go to step 7.
6. Are you working on a power distribution unit with tripped breakers?
   • No: Exchange the mainline ac power cable or power distribution unit (as installed).

     This ends the procedure.

   • Yes: Perform the following:
     1. Reset the tripped power distribution breaker.
     2. Verify that the removable ac line cord is not the problem. Replace the cord, as installed, if it is defective.
     3. Install a new power supply (as installed) in all power locations until the defective one is found.

     This ends the procedure.

7. Does the unit you are working on have ac power jumper cables installed?
   Note:
   The ac power jumper cables connect from the ac module, or the power distribution unit to the power supplies.
   • Yes: Continue with the next step.
   • No: Go to step 11.
8. Are the ac power jumper cables connected and seated correctly at both ends?
   • Yes: Continue with the next step.
   • No: Connect the ac power jumper cables correctly at both ends.

     This ends the procedure.

9. Perform the following:
   1. Disconnect the ac power jumper cables from the ac module, or power distribution unit.
   2. Use a multimeter to measure the ac voltage at the ac module or power distribution unit (that goes to the power supplies).

   Is the ac voltage at the ac module or power distribution unit from 200 V ac to 240 V ac, or from 100 V ac to 127 V ac?

   • Yes: Continue with the next step.
   • No: Exchange the following as they are installed (see DUMMY PAGE FOR Part information):
     • AC module
     • Power distribution unit

     This ends the procedure.

10. Perform the following:
    1. Connect the ac power jumper cables to the ac module, or power distribution unit.
    2. Disconnect the ac power jumper cable at the power supplies.
    3. Use a multimeter to measure the voltage of the power jumper cables input to the power supplies.

    Is the voltage 200 V ac to 240 V ac or 100V ac to 127 V ac for each power jumper cable?

    • No: Exchange the power jumper cable.

      This ends the procedure.

    • Yes: Exchange the following parts, as installed, one at a time:

      1. Table 19.

         Enclosure	FRU
         5088, 0588	Tower backplane assembly
         5094, 5294, 8094-002	Tower backplane assembly
         5095, 0595	Tower backplane assembly
         7311-D11, 7314-G30, 5790 or 5796	I/O backplane
         7311-D20	I/O backplane

      2. Display unit
      3. Power supply 1
      4. Power supply 2
      5. Power supply 3

      This ends the procedure.

11. Perform the following:
    1. Disconnect the mainline ac power cable (to the expansion unit) from the customer's ac power outlet.
    2. Exchange the following FRUs, one at a time:
       • Power supply.

       • Table 20.

         Enclosure	FRU
         5088, 0588	Tower backplane assembly
         5094, 5294, 8094-002	Tower backplane assembly
         5095, 0595	Tower backplane assembly
         7311-D11, 7314-G30, 5790 or 5796	I/O backplane
         7311-D20	I/O backplane

    3. Reconnect the mainline ac power cables (from the expansion unit) into the power outlet.
    4. Attempt to power on the system.

    Does the expansion unit power on?

    • Yes: The unit you exchanged was the failing item.

      This ends the procedure.

    • No: Repeat this step and exchange the next FRU in the list. If you have exchanged all of the FRUs in the list, ask your next level of support for assistance.

      This ends the procedure.

12. Is there a reference code displayed on the display panel for the I/O unit that does not power on?
    • Yes: Continue with the next step.
    • No: Replace the following:

      Table 21.

      Enclosure	FRU
      5088, 0588	Tower backplane assembly
      5094, 5294, 8094-002	Tower backplane assembly
      5095, 0595	Tower backplane assembly
      7311-D11, 7314-G30, 5790 or 5796	I/O backplane
      7311-D20	I/O backplane

      This ends the procedure.

13. Is the reference code 1xxx xx2E?
    • Yes: Continue with the next step.
    • No: Use the new reference code and return to Starting a Service Call.

      This ends the procedure.

14. Do the SPCN optical cables (A) connect the failing unit (B) to the preceding unit in the string or loop?

    .---------.      (A) SPCN                               
    | System  |  Optical Cables -.      .----- SPCN         
    | Unit    |                  |      V   Optical Adapter 
    | SPCN 0  |        .-.       V    .-.                   
    '----.----'        | +------------+ |                   
         |             | +------------+ |                   
    .----'----. .-------'-+    .-------'-+ .---------.      
    |  J15    | |Sec   J16|    |Sec   J15| |    Sec  |      
    |Sec Unit +-+UNIT  J15|    |Unit  J16+-+J15 Unit |      
    |  1      | |  2      |    |  3      | |      4  |      
    '---------' '---------'    '---------' '---------'      
                                   ^                        
                                   |                        
                                   '---- (B) Failing Unit

    • Yes: Continue with the next step.
    • No: Go to step 18.
15. Remove the SPCN optical adapter (A) from the preceding frame in the string that cannot become powered on.

    .---------.          .--- (A) SPCN Optical Adapter 
    | System  |          |                             
    | Unit    |          V                             
    | SPCN 0  |         .-.            .-.             
    '----.----'         | +------------+ |             
        322             | +------------+ |             
    .----'----. .-------'-+    .-------'-+ .---------. 
    |   J15   | |Sec   J16|    |Sec   J15| |    Sec  | 
    |Sec Unit +-+Unit  J15|    |Unit  J16+-+J15 Unit | 
    |  1      | |  2      |    |  3      | |      4  | 
    '---------' '---------'    '---------' '---------' 
                                     ^                 
                                     |                 
                                     '-- Failing Unit

16. Perform the following:
    Notes:
    1. The cable may be connected to either J15 or J16.
    2. Use an insulated probe or jumper when performing the voltage readings.
    1. Connect the negative lead of a multimeter to the system frame ground.
    2. Connect the positive lead of a multimeter to pin 2 of the connector from which you removed the SPCN optical adapter in the previous step of this procedure.
    3. Note the voltage reading on pin 2.
    4. Move the positive lead of the multimeter to pin 3 of the connector or SPCN card.
    5. Note the voltage reading on pin 3.

    Is the voltage on both pin 2 and pin 3 from 1.5 V dc to 5.5 V dc?

    • Yes: Continue with the next step.
    • No: Exchange the following:

      Table 22.

      Enclosure	FRU
      5088, 0588	Tower backplane assembly
      5094, 5294, 8094-002	Tower backplane assembly
      5095, 0595	Tower backplane assembly
      7311-D11, 7314-G30, 5790 or 5796	I/O backplane
      7311-D20	I/O backplane

      This ends the procedure.

17. Exchange the following FRUs, one at a time):
    1. In the failing unit (first frame with a failure indication), replace the following:

       Table 23.

       Enclosure	FRU
       5088, 0588	Tower backplane assembly
       5094, 5294, 8094-002	Tower backplane assembly
       5095, 0595	Tower backplane assembly
       7311-D11, 7314-G30, 5790 or 5796	I/O backplane
       7311-D20	I/O backplane

    2. In the preceding unit in the string, replace the FRU in Table 23.
    3. SPCN optical adapter (A) in the preceding unit in the string.
    4. SPCN optical adapter (B) in the failing unit.
    5. SPCN optical cables (C) between the preceding unit in the string and the failing unit.

    This ends the procedure.

     
          (A) SPCN
           Optical            .----- (C) SPCN        
           Adapter ----.      |      Optical Cables  
                       |      |                      
                       |      |      .-- (B) SPCN    
    .---------.        |      |      |      Optical  
    | System  |        |      |      |      Adapter  
    | Unit    |        V      |      V               
    | SPCN 0  |      .-.      V     .-.              
    '----.----'      | +------------+ |              
         |           | +------------+ |              
    .----'----. .-------'-+  .-------'-+ .---------. 
    |Sec J15  | |  Sec J16|  |Sec   J15| |    Sec  | 
    |Unit  J16+-+J15 Unit |  |Unit  J16+-+J15 Unit | 
    |  1      | |      2  |  |  3      | |      4  | 
    '---------' '---------'  '---------' '---------' 
                                   ^                 
                                   |                 
                                   |                 
                                   '--- Failing Unit

18. Perform the following:
    1. Power off the system.
    2. Disconnect the SPCN frame-to-frame cable from the connector of the first unit that cannot be powered on.
    3. Connect the negative lead of a multimeter to the system frame ground.
    4. Connect the positive lead of the multimeter to pin 2 of the SPCN cable.
       Note:
       Use an insulated probe or jumper when performing the voltage readings.
    5. Note the voltage reading on pin 2.
    6. Move the positive lead of the multimeter to pin 3 of the SPCN cable.
    7. Note the voltage reading on pin 3.

    Is the voltage on both pin 2 and pin 3 from 1.5 V dc to 5.5 V dc?

    • No: Continue with the next step.
    • Yes: Exchange the following FRUs one at a time:
      1. Iin the failing unit, replace the following:

         Table 24.

         Enclosure	FRU
         5088, 0588	Tower backplane assembly
         5094, 5294, 8094-002	Tower backplane assembly
         5095, 0595	Tower backplane assembly
         7311-D11, 7314-G30, 5790 or 5796	I/O backplane
         7311-D20	I/O backplane

      2. In the preceding unit in the string, replace the FRU in Table 24.
      3. SPCN frame-to-frame cable.

      This ends the procedure.

19. Perform the following:
    1. Follow the SPCN frame-to-frame cable back to the preceding unit in the string.
    2. Disconnect the SPCN cable from the connector.
    3. Connect the negative lead of a multimeter to the system frame ground.
    4. Connect the positive lead of a multimeter to pin 2 of the connector.
       Note:
       Use an insulated probe or jumper when performing the voltage readings.
    5. Note the voltage reading on pin 2.
    6. Move the positive lead of the multimeter to pin 3 of the connector.
    7. Note the voltage reading on pin 3.

    Is the voltage on both pin 2 and pin 3 from 1.5 V dc to 5.5 V dc?

    • Yes: Exchange the following FRUs one at a time:
      1. SPCN frame-to-frame cable.
      2. In the failing unit, replace the following:

         Table 25.

         Enclosure	FRU
         5088, 0588	Tower backplane assembly
         5094, 5294, 8094-002	Tower backplane assembly
         5095, 0595	Tower backplane assembly
         7311-D11, 7314-G30, 5790 or 5796	I/O backplane
         7311-D20	I/O backplane

      3. In the preceding unit in the string, replace the FRU in Table 25.

      This ends the procedure.

    • No: Exchange the FRU in Table 25 from the unit from which you disconnected the SPCN cable in the previous step of this procedure.

      This ends the procedure.