Section 4 TROUBLESHOOTING CHARTS E.  FLASH  CODE:  46 51587   CODE: P166  1  -  BATTERY  VOLTAGE  LOW STEP/SEQUENCE 46-4 Check  for  Bad  Battery l Pull  out  both  DDEC  circuit  breaker buttons  (CB  20+21). l Read  voltage  between  battery side  (hot  side)  of  DDEC  circuit breaker (red lead) and good ground  (black  lead). l Repeat  voltage  reading  at other  fuseholder. 46-5 Ground  Check  at  ECM l Disconnect  the  5-way  power harness  connector  at  ECM  (if you have not previously done so). l Read  voltage  on  socket  C of  5-way  power  harness  connector (red  lead)  to  socket  (black  lead). l Also read voltage on socket A (red lead)  to  socket  D  (black  lead). 46-6 Check  ECM  Connectors l Check  terminals  at  5-way power  harness  connector  (both the ECM and harness side) for damage;  bent,  corroded,  and unseated  pins  or  sockets. RESULT Less  than  or equal  to  11.5  volts  on either  reading. Greater  than 11.5 volts on both readings. Less  than  or equal  to  11.5  volts  on either  reading. Greater  than 11.5 volts on both readings. Terminals   and connectors  are  okay. Problem  found. WHAT  TO  DO  NEXT The  Battery  +  line  near Battery  is  open,  or  a  corroded connection  exists  at  Battery  + terminal.  Repair  problem. Then  go  to  46-30. The  Battery  +  line  between  the DDEC circuit breaker and ECM has an open, or 5-way power harness  connector  has  a corroded   connection.   Repair problem.  Then  go  to  48-30. The  ground  wire  (ckt  #150)  is open or has a corroded connection.  Repair  ground  wire. Then  go  to  46-30. Go  to  46-6. Replace ECM (para 7-29.1). Then go  to  46-30. Repair   terminals/connectors (para  7-77).  Then  go  to  46-30. H-219