POINT TYPE IGNITION
See Figure 1
To easily diagnose problems with your point type ignition, use the following chart.
The points should be replaced every 12,000 miles (24,000 miles with transistorized ignition since the points do not carry as much current and do not wear as quickly), or any time they are found to be badly pitted, worn, or burned.
Replace the condenser whenever the points are replaced, or if it is suspected of being defective. On Toyota passenger cars the condenser is located on the outside of the distributor.
See Figure 2
Troubleshooting this system is easy, but you must have an accurate ohmmeter and voltmeter. The numbers in the diagram correspond to the numbers of the following troubleshooting steps. Be sure to perform each step in order.
- Check for a spark at the spark plugs by hooking up a timing light in the usual manner. If the light flashes, it can be assumed that voltage is reaching the plugs, which should then be inspected, along with the fuel system. If no flash is generated, go on to the following ignition checks.
- Check all wiring and plastic connectors for tight and proper connections.
- (1) With an ohmmeter, check between the positive (+) and negative (-) primary terminals of the ignition coil. The resistance (cold) should be 1.3-1.7 ohms. Between the primary terminal and the high tension terminal, the resistance (cold) should be 12-16k ohms. (2) The insulation resistance between the (+) primary terminal and the ignition coil case should be infinite.
- The resistor wire (brown and yellow) resistance should be 1.2 ohms (cold). To measure, disengage the plastic connector at the igniter and connect one wire of the ohmmeter to the yellow wire and one to the brown.
- Remove the distributor cap and ignition rotor. (1) Check the air gap between the timing rotor spoke and the pick-up coil. When aligned, the air gap should be 0.008-0.016 in. (0.20-0.40mm). You will probably have to bump the engine around with the starter to line up the timing rotor. (2) Unplug the distributor connector at the distributor. Connect one wire of the ohmmeter to the white wire, and one wire to the pink wire. The resistance of the signal generator should be 130-190 ohms.
- Check the igniter last; connect the(-) voltmeter wire to the (-) ignition coil primary terminal, and the (+) voltmeter wire to the yellow resistor wire at the connector unplugged in Step 4. With the ignition switch turned on On (not Start) the voltage should measure 12 volts.
- Check the voltage between the (-) ignition coil primary terminal and the yellow resistor wire again, but this time use the ohmmeter as resistance. Using the igniter end of the distributor connector unplugged in Step 5, connect the positive (+) ohmmeter wire to the pink distributor wire, and the negative (-) ohmmeter wire to the white wire.
Select either the 1 ohms or 10 ohms range of the ohmmeter. With the voltmeter connected as in Step 6 (1), and the ignition switch turned to On (not Start), the voltage should measure nearly zero.