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Ignition System - Hitachi Electronic Nissan Stanza II

Ignition System 4 illustrations ~833 words

DESCRIPTION

The Hitachi Computerized Ignition system controls ignition timing by adjusting to engine operating conditions. The optimum ignition timing for each driving condition is pre-programmed in the system. Ignition timing is determined by an electric signal contained in the unit.

CRANK ANGLE SENSOR

The crank angle sensor is a basic component of the entire computerized ignition system and is built into the distributor. It monitors engine RPM, and piston position and sends this information to the Electronic Control Unit (ECU).

The crank angle sensor has a rotor plate and a wave forming circuit. The rotor plate has 360 slits in one degree increments for engine speed signal and 4 or 6 slits for piston position signal. Light Emitting Diodes (LEDs) and photo diodes are built in the wave forming circuit. When the signal rotor passes between the LED and photo diode, the slits in the rotor plate alternately cuts the light. This is converted into an on-off pulse by the wave forming circuit, which is sent to the ECU. (Scheme 1)

Hitachi Computerized Ignition System. Scheme 1

Scheme 1: Hitachi Computerized Ignition System
Scheme 1: Hitachi Computerized Ignition System

IGNITION COIL

The ignition coil has a built-in power transistor which amplifies the signal from the control unit. The amplified signal turns the ignition coil primary circuit on and off, inducing the proper high voltage in the secondary circuit.

Needle Type Speedometer Models

The needle type speed sensor consists of a reed switch, which is installed in the speedometer unit and transforms vehicle speed into a pulse signal to the ECU.

Digital Type Speedometer Models

The digital type speed sensor consists of an LED, photo diode, shutter and wave forming circuit. Its principle is the same as that of the crank angle sensor.

VEHICLE SPEED SENSOR (VSS)

Raise drive wheels. Remove ECU 16-pin connector. Turn ignition switch to "ON" position. Rotate drive wheel by hand. Using an ohmmeter, check resistance between harness connector terminal No. 29 and ground. It should alternate between zero and infinity ohms on needle type speed sensor. On digital type speed sensor, voltage reading should vary between zero volt to approximately 5 volts.

On Sentra models the ignition coil primary resistance should be 0.84-1.02 ohms and the secondary coil resistance should be 8,200-12,400 ohms. Replace ignition coil if not within specifications.

On all but Sentra models the ignition coil primary resistance should be 0.80-1.00 ohms and the secondary coil resistance should be 7,600-11,400 ohms. Replace ignition coil if not within specifications.

POWER TRANSISTOR

Note. The power transistor and coil are tested together. The power transistor cannot be tested by itself.

Note. On models equipped with dual coils, DO NOT disconnect "T" type harness connector for ignition coil.

All Exc. 200SX XE & 300ZX

Perform following checks on power transistor/ignition coil harness pigtail, terminal side. Use ohmmeter for following tests. Disconnect harness connector for ignition coil and power transistor.

  1. Connect Red lead to terminal No. 1 and Black lead to terminal No. 3, or connect Red lead to terminal No. 4 and Black lead to terminal No. 3. (Scheme 2) The reading should be no continuity.
  2. Connect Black lead to terminal No. 1 and Red lead to terminal No. 3, or connect Black lead to terminal No. 4 and Red lead to terminal No. 3. (Scheme 2) Continuity should exist.
  3. Connect Red lead to terminal No. 1 and Black lead to terminal No. 2, or connect Red lead to terminal No. 4 and Black lead to terminal No. 2. (Scheme 2) The reading should be no continuity.
  4. Connect Black lead to terminal No. 1 and Red lead to terminal No. 2, or connect Black lead to terminal No. 4 and Red lead to terminal No. 2. (Scheme 2) Continuity should exist.

Power Transistor Terminal Check Points. Scheme 2

Scheme 2: Power Transistor Terminal Check Points
Scheme 2: Power Transistor Terminal Check Points

200SX XE

  1. Turn engine off. Ensure continuity exists between harness connector, ECU and power transistor. Check fusible link "G" (located in fusible link holder), ignition switch and continuity of ignition coil.
  2. Disconnect ignition coil and power transistor harness connector. With an ohmmeter, check continuity between terminals No. 2 and 1, terminals No. 2 and 3 and terminals No. 3 and 1. Continuity should exist between all these terminals. (Scheme 3)
  3. If readings are not as specified, replace power transistor.

Power Transistor Check Points. Scheme 3

Scheme 3: Power Transistor Check Points
Scheme 3: Power Transistor Check Points

300ZX

  1. Turn engine off. Check harness continuity between power transistor and ECU. If okay, proceed to next step.
  2. To check power transistor, disconnect harness connector to power transistor. (Scheme 4) On power transistor side of connector, connect ohmmeter positive probe to terminal No. 1 and negative probe to terminal No. 3. No continuity should exist.
  3. Connect ohmmeter negative probe to terminal No. 1 and positive probe to terminal No. 3. Continuity should exist.
  4. Connect ohmmeter positive probe to terminal No. 1 and negative probe to terminal No. 2. No continuity should exist.
  5. Connect ohmmeter negative probe to terminal No. 1 and positive probe to terminal No. 2. Continuity should exist.
  6. If readings are not as specified, replace power transistor.

Power Transistor Check Points. Scheme 4

Scheme 4: Power Transistor Check Points
Scheme 4: Power Transistor Check Points