turn on the ignition (DO NOT START ENGINE). Check the voltage between terminals 1 (black) and ground, then terminal 2 (orange), by slowly rotating the distributor shaft by hand. Voltage should fluctuate between 0 and 5 volts DC when measured on a 12 volt DC scale.
In This Article...
How Can Optical Distributor Be Tested?
The majority of Nissan automobiles from 1984 and later include optical disc sensor distributors.
Problem:
Solution:
The coil is controlled by a power transistor in many Nissan automobiles (or igniter). On optical distributors, the power transistor is a separate component. It enables the low current signal from the ECU to turn on the ignition coil’s primary circuit (higher current). As a result, the secondary windings of the coil experience high voltage induction, which generates spark for the distributor cap and plugs. This transistor will not provide the required spark if it is malfunctioning. Although the distributor is frequently held responsible for this, run the tests listed below before replacing it.
Before replacement, tests:
1. Examine the coil and power transistor. In order to perform particular tests, consult the service manual.
2. Inspect the fuse box’s ECC fuse and/or fusible link.
3. Verify the ECC relay for 12V, which is often a black/white wire.
4. Verify the distributor for 12 volts; normally, pin 2 is an orange wire.
5. Verify that all wiring to and from the computer, transistor, and distributor is continuous.
6. Remove the distributor cap and the distributor but leave the sensor’s harness connected if you want to test the optical sensor in the distributor. activate the ignition switch (Do Not Start The Engine). Check the voltage between terminal 1 (black) and ground, then between terminal 2 (orange), by slowly rotating the distributor shaft by hand. Voltage should range between 0 and 5 volts DC when measured on a 12V DC scale.
Note: Engine oil coating the optical disc or cap terminals may be the cause of a 1993–1996 Altima, 2.4L, Cardone P/N 31–58470 with no start or driveability. Before putting the distributor in, replace the PCV valve. view Figure 1
An optical distributor is what?
The distributor instructs the ignition coil to fire using the trigger method. One type of trigger is optical. (A common example is the Mallory Unilite.)
Distributors of optical triggers are an improvement over distributors of points. They utilize the parts listed below:
- a photoreceptor and an LED-equipped electronic module
- a distributor shaft-mounted interrupter wheel.
How does it work?
- The interrupter wheel rotates in tandem with the distributor.
- The windows in the interrupter wheel deflect the LED’s light beam.
- A pulse is produced when the light enters the photo receptor.
- The pulses are picked up by the ignition control module.
- The coil fires as a result of the control module cutting off the electricity to it.
- The high-voltage is transferred to the proper spark plug via the rotor inside the cap after being restored there.
How does it affect performance?
A better option than points is an optical trigger distributor. A Magnetic Trigger Distributor is frequently preferred, though. The optical signal quality may be negatively impacted by heat and debris.
Additionally, optical triggers often need a 3-wire connection. (a ground, a 12-volt input, and an output trigger signal)
How is an optical sensor tested?
Optically based sensors should only be cleaned with compressed air before testing. NEITHER liquid cleansers nor solvents should be used on the sensors. If you do, you will harm them irreparably.
Simply disrupt the signal between the two sensors on the optical sensor PCB while testing optical sensors with a nonmetallic object (use nonmetallic material in order to avoid shorts if you accidentally touch an electrical component). The appropriate LED on the Main PCB will turn on when the signal is broken when you move an object between the two sensors on the optical sensor PCB, and it will go out when you remove the thing from between the two sensors.
Given that continuity in the harness is good on all leads and the matching LED on the Main PCB fails to illuminate but the Main PCB is operating OK, the optical sensor is likely faulty (check only if you replaced the harness). For information on where the necessary indication LEDs are located on the Main PCB, consult the replacement section for the relevant optical sensor PCB.
Your car won’t start
A specific series of circumstances must take place in order for a car to start. The battery feeds the engine with current when you turn the key in the ignition. The engine can then begin spinning and consuming gasoline and air. Spark plugs employ electrical current to burn the fuel mixture as it enters the engine and initiate the combustion process that propels your car forward.
The spark plugs won’t receive the electrical current necessary to ignite the gasoline mixture if the distributor isn’t operating.
However, other broken parts, such as the fuel pump, ignition switch, start, fuel injectors, alternator, spark plugs, and more, might make it difficult to start your automobile. Before presuming that a new distributor is necessary, you should rule out all other options.
Your engine keeps misfiring or backfiring
When fuel in one of the cylinders fails to ignite, the engine misfires. Typically, a misfire feels like a jerking sensation. Usually, it will occur when accelerating, idling, or starting.
Backfiring is a related problem. Unburned fuel that has just left an engine cylinder might backfire when it comes in contact with the following spark plug. Your car can stall if it backfires.
Your car is shaking
Shaking is a sign of many various problems with your car, particularly problems with the wheels and tires. However, because a defective distributor can impact how the distributor rotor rotates, shaking is one of the most typical bad distributor symptoms. The engine that isn’t running may also be the cause of the trembling.
Your check engine light comes on
When the engine’s internal computer senses a problem, the check engine light is an indicator that flashes on your dashboard. The firing cycle is one of the things the computer keeps an eye on.
Your check engine light is probably going to turn on because of a bad distributor that is interfering with the engine’s ability to ignite fuel.
You hear a high-pitched noise coming from under the hood
One of the signs of a faulty distributor to look out for is noises. When your engine misfires or backfires, you might hear popping noises, but a defective distributor can also produce a loud screaming sound.
If debris and grease residues are clogging the distributor and preventing the bearings from rotating, you’ll probably hear this noise.
You failed your last emissions test
One of the warning signs of a faulty distributor is noises. Your engine may make popping sounds when it misfires or backfires, but a defective distributor can also produce a loud screaming sound.
This noise is most likely to be heard if the distributor is clogged with debris and grease residues that are keeping the bearings from rotating.
A distributor cap should have how many ohms, right?
As shown in Fig. 3-1, test the ignition coil’s primary and secondary resistance using an ohmmeter. Table c provides resistance values. Any coil with a higher main or secondary resistance should be replaced.
Between terminals 1 and 15, a primary coil resistance is being measured with an ohmmeter (symbolized). All but Digifant I are displayed at the top. Shown at the bottom is Digifant I. Secondary resistance can also be measured.
Each spark plug wire should be examined by removing the ends from the distributor cap and the spark plug, as shown in Fig. 3-2, and measuring the resistance with an ohmmeter. Spark plug wire resistance should range from 4600 to 7400 ohms. The coil wire’s resistance should range from 1200 to 2800 ohms.
Using an ohmmeter, the resistance of the coil wire and spark plug wire is measured (shown schematically).
Check the wire and the connectors independently, as indicated in Fig. 3-3, if the measured resistance is too high. Additionally, inspect the connectors for corrosion. Carefully remove the connectors. Twist before pulling. The connection is destroyed and both the connector and the wire need to be replaced if the metal wire end is left in the connector. The spark plug connectors’ resistance should range from 4000 to 6000 ohms. The suppression connectors that attach to the distributor cap should have a resistance of 600 to 1400 ohms. The wire should have almost 0 ohms of resistance. Replace any wires or connectors that have too much resistance. Individual connectors and cables are accessible through licensed Volkswagen dealers, albeit not all dealers may carry them in stock.
Do not wriggle the connectors when taking them out to prevent breaking the distributor cap. To loosen, twist if necessary. After that, simply pull away from the cap.
A distributor cap might prevent a spark.
Depending on the cause, misfiring is a frequent drivability issue that may take some time to diagnose. One or more cylinders fail to ignite properly in an engine when it misfires, typically due to ignition or fuel-related problems. Power loss following an engine misfire is inversely correlated with how severe the misfire was.
The engine may shake so violently when idling that vibrations are audible throughout the entire car. One or more cylinders may be misfiring, and the engine may be operating poorly. The check engine light can illuminate or continue to flash.
An ignition system issue is the most frequent reason for a misfire. Lack of spark, an unbalanced air/fuel mixture, or a loss of compression can all result in misfiring.
This article focuses on identifying the cause of misfires brought on by spark loss. Anything that stops coil voltage from leaping the electrode gap at the spark plug’s tip causes loss of spark. This includes spark plugs that are dirty, worn, or damaged, poor plug wires, or a shattered distributor cap.
Misfiring may occasionally result from improper sparking or high-voltage electrical leakage rather than a complete loss of spark.
Why is there no spark in my distributor?
The coil voltage required to ignite the spark plugs is produced by the ignition coil and is controlled by the ignition control module.
Your automobile will occasionally stall if your ignition control module is malfunctioning. The automobile won’t start if the ignition control module has completely failed since it will only produce a weak spark.
Make that the switch and terminals are clear of rust, and if required, replace any damaged or broken spark plug wires.
Allowing the car to idle for 30 minutes and then tapping the ignition module with a screwdriver is an easy technique to test the ignition module. If the vehicle stalls, there is a good chance that your ignition module is malfunctioning.
How can a damaged distributor rotor be identified?
Because the cylinders will try to ignite but fail, if the distributor rotor and cap are broken, your car may make some extremely odd noises. When the distributor rotor and cap are failing, you can hear a tapping, clicking, or spitting sound.
Ask that the ignition system be inspected for flaws or issues every time your car has normal maintenance. Get help from a skilled mobile automotive repair from YourMechanic if you have any trouble starting your automobile.
What is an ignition system using an optical sensor?
A Light Emitting Diode (LED) and a photo receptor are used in an optical trigger. A wheel attached to the distributor shaft obstructs the LED’s light beam. The receptor, which is in charge of producing the trigger signal, has “windows that let the LED beam shine through.