Chapter 5
Engine electrical systems
5-3
6.2 To use a calibrated ignition tester (available at most auto
parts stores), simply disconnect a spark plug wire, attach the
wire to the tester and clip the tester to a good ground-if there
Is enough power to fire the plug, sparks will be clearly visible
between the electrode tip and the tester body as the engine is
turned over
cables with identical parts. Cables have characteristics that make them
easy to identify: positive cables are usually red, larger in cross section and
have a larger diameter battery post clamp; ground cables are usually
black, smaller in cross-section and have a slightly smallerdiameterclamp
for the negative post.
6 Clean the threads of the solenoid or ground connection with a wire
brush to remove rust and corrosion. Apply a light coat of battery terminal
corrosion inhibitor, or petroleum jelly, to the threads to prevent future cor-
rosion.
7 Attach the cable to the solenoid or ground connection and tighten the
mounting nut/bolt securely.
8 Before connecting a new cable to the battery, make sure that it reach-
es the battery post without having to be stretched.
9 Connect the positive cable first, followed by the negative cable.
5 Ignition system-general information and precautions
When working on the ignition system, take the following precautions:
a) Do not keep the ignition switch on for more than 10 seconds if the
engine will not start.
b) Always connect a tachometer in accordance with the manufactur-
er’s instructions. Some tachometers may be incompatiblewith this
ignitionsystem. Consultadealerservicedepartment before buying
a tachometer for use with this vehicle.
c) Never allow the primary terminals of the ignition coil to touch
ground.
d) Do not disconnect the battery when the engine is running.
The ignition system includes the ignition switch, the battery, the coil,
the primary (low voltage) andsecondary (high voltage) wiring circuits, the
distributor and the spark plugs. On later distributors not using avacuum
or centrifugal advance, the ignition timing is controlled by the Electronic
Control Unit (ECU). ’ +
6 Ignition system - check
Refer to illustration 6.2
Warning:
Because of the very high voltage generated by the ignition sys-
tem, extreme care should be taken when this check is performed.
1 If the engine turns over but won’t start, disconnect the sparkplug wire
from any sparkplug and attach it to a calibrated ignition tester (available at
7.2 To remove a typical coil from the engine compartment,
I disconnect the primary wires and the high-voltage lead, then
unbolt the bracket
1 Negative primary wire
4 Ballast resistor
2 Positive primary wire
5 High-voltage lead
3 Bracket
most auto parts stores). Note:
Be sure to purchase the correct tester for
either an electronic distributor or points distributon depending which sys-
tem the vehicle is equipped with.
2 Connect the clip on the tester to a bolt or metal bracket on the engine
(see illustration). If you’re unable to obtain a calibrated ignition tester, re-
move the wire from one of the spark plugs and, using an insulated tool,
hold the end of the wire about l/4-inch from a good ground.
3 Crank the engine and watch the end of the tester or sparkplug wire to
see if bright blue, well-defined sparks occur. If you’re not using acalibrated
tester, have an assistant crank the engine for you. Warning:
Keep ctearof
drivebelts and other moving engine components that could injure you.
4 If sparks occur, sufficient voltage is reaching the plug to fire it (repeat
the check at the remaining plug wires to verify the wires, distributor cap,
rotor and coil are OK. However, the plugs themselves may be fouled, so
remove them and check them as described in Chapter 1.
5 If no sparks or intermittent sparks occur, remove the distributor cap
and check the cap and rotor as described in Chapter 1. If moisture is pres-
ent, dry out the cap and rotor, then reinstall the cap.
6 If there isstill nospark, detachthecoilsecondarywirefromthedistrib-
utor cap and hook it up to the tester (reattach the plug wire to the spark
plug), then repeat the spark check. Again, if you don’t have a tester, hold
the end of the wire about l/4 inch from a good ground. If sparks occur now,
the distributor cap, rotor or plug wire(s) may be defective.
7 If no sparks occur, check the wire connections at the coil to make sure
they’re clean and tight. Check for voltage to the coil. Make any necessary
repairs; then repeat the check again.
8 If there’s still no spark, the coil-to-cap wire may be bad (check the re-
sistance with an ohmmeter- it should be 7000 ohms per foot or less). If a
known good wire doesn’t make any difference in the test results, the igni-
tion coil, module or pick-up coil may be defective.
7 Ignition coil and ballast resistor - check and replacement
Ignition coil
Refer to
illustrations 7.2,
7.4a,
7.4b, 7.5a and 7.5b
1 Detach the cable from the negative battery terminal.
2 Mark the wires and terminals with pieces of numbered tape, then re-
move the primary wires and the high-voltage
lead from the coil (seeillus-
tration). Disconnect the coil mounting bracket, remove the coil/bracket
assembly, clean the outer case and check it for cracks and other damage.
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