STEP/SEQUENCE RESULT WHAT TO DO NEXT TM 9-2320-363-20-1 Section 4 TROUBLESHOOTING CHARTS E.  FLASH CODE: 87 (Cont'd) J1587 CODE: P73.4 PUMP PRESSURE CIRCUIT FAILED LOW .  (Below) P108.4 BAROMETRIC PRESSURE CIRCUIT FAILED LOW - (TBD) 87-4 Check for Short to +5 Volts Turn ignition off. Between 4 Go to 87-5. Remove jumper wire. and 6 volts. Turn ignition on. Read voltage on PGC sensor Less than 4 volts. Go to 87-8 harness connector socket C (red lead) and socket A (black lead). Greater than Go to troubleshooting chart for 6 volts. Code 86. 87-5 Check for Signal Open Turn ignition off. Less than or Go to 87-6 Disconnect vehicle harness equal to 5 ohms. connector at the ECM. Install a jumper wire between Greater than Signal line (ckt #749) is shorted sockets A and B of the PGC 5 ohms or open. to return line (ckt #952) or battery sensor connector. ground.  Repair short.  Then Read resistance between sockets go to 87-30. D3 and C3 on the vehicle harness connector. 87-6 Check for Short Remove jumper wire. Less than or Signal line (ckt #749) is shorted Disconnect the vehicle harness equal to 10,000 ohms to return line (ckt #952) or connector at the ECM. on either reading. battery ground.  Repair short. Read resistance between sockets Then go to 87-30. A and B on the PGC sensor connector. Greater than Go to 87-10. Also read resistance between 10,000 ohms or open socket B and a good ground. 87-7 Check ECM Connectors Check terminals at the ECM Terminals and Replace ECM. Then go to 87-30. vehicle harness connector (both connectors okay. the ECM and harness side) for damaged, bent, corroded and Problem found. Repair terminals/connectors. unseated pins or sockets.  Especially Then go to 87-30. D3, C3, A3 pins and terminals. Change 3  3-345.405