The main differences between the 1975-77 and 1978 systems are: (1) the 1975-77 system uses an external ballast resistor located next to the ignition coil, and (2) the earlier system uses a wiring harness with individual eyelet connectors to the electronic unit, while the later system uses a multiple plug connector. You will need an accurate voltmeter and ohmmeter for these tests, which must be performed in the order given.
- Check all connections for corrosion, looseness, breaks, etc., and correct if necessary. Clean and gap the spark plugs.
2a. Disconnect the harness (connector of plug) from the electronic unit. Turn the ignition switch On. Set the voltmeter to the DC 50v range. Connect the positive (+) voltmeter lead to the black/white wire terminal, and the negative (-) lead to the black wire terminal. Battery, voltage should be obtained. If not, check the black/white and black wires for continuity; check the battery terminals for corrosion; check the battery state of charge.
2b. Next, connect the voltmeter (+) lead to the blue wire and the (-) lead to the black wire. Battery voltage should be obtained. If not check the blue wire for continuity; check the ignition coil terminals for corrosion or looseness; check the coil for continuity. On 1975-77 models, also check the external ballast resistor.
- Disconnect the distributor harness wires from the ignition coil ballast resistor on 1975-77 models, leaving the ballast resistor-to-coil wires attached. On 1978 models, disconnect the ignition coil wires. Connect the leads of an ohmmeter to the ballast resistor outside terminals (at each end) for 1975-77, and to the two coil terminals for 1978. With the ohmmeter set in the X1 range, the following model years should show a reading of 1.6-2.0 omega : 1976 710, 610; 1977 810, 710 models.
The following models should show a reading of approximately 0 omega : 1975 710; 1978 810, 200SX. The maximum allowable limit for the 1.6-2.0 omega range models is 2.0 omega . The limit for the 0 omega models is 1.8 omega . If a reading higher than the limit is received, replace the ignition coil assembly.
- Disconnect the harness from the electronic control unit. Connect an ohmmeter to the red and the green wire terminals. Resistance should be 720 omega . If far more or far less, replace the distributor pick-up coil.
- Disconnect the anti-dieseling solenoid connector. Connect a voltmeter to the red and green terminals of the electronic control harness. When the starter is cranked, the needle should deflect slightly. If not, replace the distributor pick-up coil.
- Reconnect the ignition coil and the electronic control unit. Leave the anti-dieseling solenoid wire disconnected. Unplug the high tension lead (coil to distributor) from the distributor and hole it 1 / 8 - 1 / 4 " from the cylinder head with a pair of insulated pliers and a heavy glove. When the engine is cranked, a spark should be observed. If not, check the lead, and replace if necessary. If still no spark, replace the electronic control unit.
- Reconnect all wires.
1976-77: connect the voltmeter (+) lead to the blue electronic control harness connector and the (-) lead to the black wire. The harness should be attached to the control unit.
1978: Connect the voltmeter (+) lead to the (-) terminal of the ignition coil and the (-) lead to ground.
As soon as the ignition switch is turned ON, the meter should indicate battery voltage. If not, replace the electronic control unit.1979-84 Models
510, 810 AND MAXIMA AND 1979-81 200SX
(SINGLE PLUG ENGINE) MODELS
- Make a check of the power supply circuit. Turn the ignition OFF, Disconnect the connector from the top of the IC unit. Turn the ignition ON. Measure the voltage at each terminal of the connector in turn by touch the probe of the positive lead of the voltmeter to one of the terminals, and touching the probe of the negative lead of the voltmeter to a ground, such as the engine. In each case, battery voltage should be indicated. If not, check all wiring, the ignition switch, and all connectors for breaks, corrosion, discontinuity, etc., and repair as necessary.
- Check the primary windings of the ignition coil. Turn the ignition OFF. Disconnect the harness connector from the negative coil terminal. Use an ohmmeter to measure the resistance between the positive and negative coil terminals. If resistance is 0.84-1.02 omega the coil is OK. Replace if far from this range. If the power supply, circuits, wiring, and coil are in good shape, check the IC unit and pick-up coil, as follows:
- Turn the ignition OFF. Remove the distributor cap and ignition rotor. Use an ohmmeter to measure the resistance between the two terminals of the pick-up coil, where they attach to the IC unit. Measure the resistance by reversing the polarity of the probes. If approximately 400 omega are indicated, the pick-up coil is OK, but the IC unit is bad and must be replaced. If other than 400 omega are measured, go to the next step.
- Be certain the two pin connector to the IC unit is secure. Turn the ignition ON. Measure the voltage at the ignition coil negative terminal. Turn the ignition OFF.
If zero voltage is indicated, the IC unit is bad and must be replaced. If battery voltage is indicated, proceed.
- Remove the IC unit from the distributor:
- Disconnect the battery ground (negative) cable.
- Remove the distributor cap and ignition rotor.
- Disconnect the harness connector at the top of the IC unit.
- Remove the two screws securing the IC unit to the distributor.
- Disconnect the two pick-up coil wires from the IC unit.
- Remove the IC unit.
- Measure the resistance between the terminals of the pick-up coil. It should be approximately 400 omega . If so, the pick-up coil is OK, and the IC unit is bad. If not approximately 400 omega , the pick-up coil is bad and must be replaced.
- With a new pick-up coil installed, install the IC unit. Check for a spark at one of the spark plugs. If a good spark is obtained, the IC unit is OK. If not, replace the IC unit.
Complete Step 1-2 of the previous procedure; the resistance should be between 1.04-1.27 omega . If not, replace ignition coil(s).
The manufacturer does not give a complete system of tests for the 1980 200SX/510 California ignition system. Therefore, before attempting anything else, try this spark performance test:
- Turn the ignition switch to the OFF position.
- On the 510 cut off the fuel supply to the engine. On the 200SX, disconnect the electronic fuel injection (EFI) fusible link.
- Disconnect the high tension cable from the distributor. Hold the cable with insulated pliers to avoid getting shocked. Position the wire about a 1 / 4 " from the engine block and have an assistant turn over the engine using the starter. A spark should jump from the cable to the engine block. If not, there is probably something wrong with the ignition system. Further testing should be left to an authorized service technician with the proper test equipment.