Equus 3551 - INNOVA Inductive Timing Light (DIS) - Manual (Page 10)

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4. Using the vacuum pump, apply the
manufacturer's specified amount of
vacuum to the distributor's vacuum port.
5. Aim the timing light at the timing marks
and rotate the Advance Control Knob
clockwise until the timing marks are
realigned to the initial (base) timing mark
as recorded in step 3.
6. The difference between the reading
obtained in step 3 (initial (base) timing)
and the value obtained in step 5 is the
vehicle's vacuum advance. Compare this
value with the manufacturer's specifications
for vacuum advance.
7. Repeat the test, as needed, for each
amount of vacuum specified by the
manufacturer's instructions.
8. Turn off the ignition and disconnect the
timing light and vacuum pump from the
engine. Unplug and reconnect the vacuum
hose to the distributor's vacuum port.
Checking Vacuum/Electronic Retard and
Electronic Advance
The procedures for checking vacuum/electronic
retard and electronic advance vary between
vehicles and manufacturers. Refer to your
vehicle's service manual for specifications and
procedures.
A vacuum pump equipped with a vacuum
gauge is required to check vacuum retard.
If the timing light fails to operate or operates
erratically, make the following checks:
1. Make sure the battery clips are firmly
connected to the battery terminals.
2. Make sure the battery clip polarity is
correct (red battery clip is connected to
the positive (+) battery terminal, black
battery clip is connected to the negative
(–) battery terminal).
3. Make sure the upper and lower ferrite
cores of the inductive pickup clip are
clean. If necessary, clean the inductive
pickup clip as described in MAIN-
TENANCE.
4. Make sure the inductive pickup clip is
properly connected to the No. 1 spark plug
cable.
5. Make sure the No. 1 spark plug is working
properly:
■ Connect the inductive pickup clip to
another spark plug cable, and press
the On/Off switch.
■ If the timing light flashes, service the
No. 1 spark plug before continuing.
TROUBLESHOOTING
NOTE
Low spark plug voltage or a faulty spark plug
wire may cause the Timing Light to operate
erratically. Try moving the inductive pickup
clip to a new location on the plug wire to
improve operation.
Some ignition systems and/or specialty spark
plug wires (solid core wires, racing wires, off-
road wires) radiate above normal Electro-
Magnetic Interference (EMI) and Radio
Frequency Interference (RFI) which can
cause improper operation of testing
equipment. Contact the manufacturers of
these parts for instructions on how to use an
inductive pickup with their systems.