Check Components

Inspect ignition coil and power transistor. See SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE section. Replace ignition coil and/or power transistor if necessary and perform FINAL CHECK  . If ignition coil and power transistor are okay, repair ECM pin terminal(s) and/or wiring harness connector.

Inspect resistor and condenser. See the SYSTEM/COMPONENT TESTS article in the ENGINE PERFORMANCE section. Replace resistor and condenser if necessary, and perform FINAL CHECK  . If resistor and condenser are okay, repair ECM pin terminal(s) and/or wiring harness connector.

Fig 1: Locating Ignition Coil Harness Connector (Sentra)

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 2: Locating Power Transistor Harness Connector (Sentra)

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 3: Locating Resistor & Condenser Harness Connector (Sentra)

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 4: Checking Power Supply (Sentra)

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 5: DTC 21, Checking Ground Circuit (Sentra)

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 6: DTC 21, Checking Output Signal Circuit (Sentra)

Courtesy of NISSAN MOTOR CO., U.S.A.

Fig 7: DTC 21, Checking Input Signal Circuit (Sentra)

Courtesy of NISSAN MOTOR CO., U.S.A.