Keep this manual for the safety
warnings and precautions, assembly,
operating, inspection, maintenance and
cleaning procedures. Write the product’s
serial number in the back of the manual
near the assembly diagram (or month
and year of purchase if product has no
number). Keep this manual and the
receipt in a safe and dry place for future
reference.
IMPORTANT SAFETY
INFORMATION
In this manual, on the labeling,
and all other information
provided with this product:
This is the safety alert
symbol. It is used to alert
you to potential personal
injury hazards. Obey all
safety messages that
follow this symbol to avoid
possible injury or death.
DANGER indicates
a hazardous
situation which, if not
avoided, will result in death or
serious injury.
WARNING
indicates a
hazardous situation which, if
not avoided, could result in
death or serious injury.
CAUTION, used
with the safety
alert symbol, indicates a
hazardous situation which, if
not avoided, could result in
minor or moderate injury.
NOTICE is used to
address practices
not related to personal injury.
CAUTION, without
the safety alert
symbol, is used to address
practices not related to
personal injury.
GENERAL SAFETY RULES
WARNING! Read all instructions
Failure to follow all instructions
listed below may result in
electric shock, re, and/or
serious injury.
The warnings, precautions,
and instructions discussed in
this instruction manual cannot
cover all possible conditions and
situations that may occur. It must
be understood by the operator that
common sense and caution are
factors which cannot be built into
this product, but must be supplied
by the operator.
SAVE THESE INSTRUCTIONS
Work area safety1.
Keep work area clean and well a.
lit. Cluttered or dark areas invite
accidents.
Keep children and bystanders b.
away while operating a diagnostic
tool. Distractions can cause you
to lose control.
Electrical safety2.
Do not expose diagnostic tools a.
to rain or wet conditions. Water
entering a diagnostic tool will
increase the risk of electric shock.
or long hair can be caught in moving
parts.
Do not abuse the cords. Never b.
use the cords for carrying, pulling
or unplugging the diagnostic
tool. Keep cords away from heat,
oil, sharp edges or moving parts.
Damaged or entangled cords
increase the risk of electric shock.
Personal safety3.
Stay alert, watch what you are a.
doing and use common sense when
operating a diagnostic tool. Do not
use a diagnostic tool while you are
tired or under the inuence of drugs,
alcohol or medication. A moment of
inattention while operating diagnostic
tools may result in serious personal
injury.
Use safety equipment. Always b.
wear eye protection. Safety
equipment such as dust mask,
non-skid safety shoes, hard hat,
or hearing protection used for
appropriate conditions will reduce
personal injuries.
Avoid accidental starting. Ensure c.
the switch is in the off-position
before plugging in. Carrying
diagnostic tools with the nger on
the switch or plugging in diagnostic
tools that have the switch on invites
accidents.
Do not overreach. Keep proper d.
footing and balance at all times.
This enables better control of the
diagnostic tool in unexpected
situations.
Dress properly. Do not wear loose e.
clothing or jewelry. Keep the hair,
clothing and gloves away from
moving parts. Loose clothes, jewelry
Diagnostic tool use and care4.
Do not force the diagnostic tool. Use a.
the correct diagnostic tool for the
application. The correct diagnostic
tool will do the job better and safer at
the rate for which it was designed.
Do not use the diagnostic tool if b.
the trigger does not turn it on and
off. Any diagnostic tool that cannot
be controlled with the trigger is
dangerous and must be repaired.
Store idle diagnostic tools out c.
of the reach of children and do
not allow persons unfamiliar
with the diagnostic tool or these
instructions to operate the
diagnostic tool. Diagnostic tools
are dangerous in the hands of
untrained users.
Maintain diagnostic tools. Check d.
for misalignment or binding of
moving parts, breakage of parts
and any other condition that may
affect the diagnostic tools operation.
If damaged, have the diagnostic
tool repaired before use. Many
accidents are caused by poorly
maintained diagnostic tools.
Use the diagnostic tool and e.
accessories, in accordance with
these instructions and in the
manner intended for the particular
type of diagnostic tool, taking into
account the working conditions and
the work to be performed. Use of
the diagnostic tool for operations
different from those intended could
result in a hazardous situation.
identical replacement parts. This
will ensure that the safety of the
diagnostic tool is maintained.
SPECIFIC SAFETY RULES
Maintain labels and nameplates on 1.
the tool. These carry important safety
information. If unreadable or missing,
contact Harbor Freight Tools for a
replacement.
Avoid unintentional starting. Prepare 2.
to begin work before connecting the
tool.
This product is not a toy. Keep it out 3.
of reach of children.
People with pacemakers should 4.
consult their physician(s) before
use. Electromagnetic elds in close
proximity to heart pacemaker could
cause pacemaker interference or
pacemaker failure.
Caution is necessary when near coil,
spark plug cables, or distributor of
running engine. Engine should be off
during distributor adjustment.
WARNING: Handling the cord on 5.
this product will expose you to lead,
a chemical known to the State of
California to cause cancer, and
birth defects or other reproductive
harm. Wash hands after handling.
(California Health & Safety Code §
When unpacking, make sure that the
item is intact and undamaged. If any parts
are missing or broken, please call Harbor
Freight Tools at 1-800-444-3353 as soon
as possible.
Timing Light Basics
Automobile engines work by mixing
air, fuel and a spark to ignite the fuel/
air mixture, creating an explosion, that
powers the vehicle. Maximum power
from the explosion must be delivered to
the engine at a precise instant. Attaining
that precise instant is called “Timing”.
Timing is essential for fuel economy and
power. Automobile engine manufacturers
determine the exact timing necessary
for every engine they build. Normal
engine and ignition system wear causes
the timing to change, reducing both fuel
Engine manufacturers use two terms
when describing timing, “advanced” and
“retarded”. Timing is advanced when the
spark occurs before the piston reaches
the top of a cylinder. Timing is retarded
when the spark occurs after the piston
has started down in the cylinder. Timing
is changed by adjusting the ignition
distributor.
To set timing, the engine
manufacturer provides “timing marks”
on engine’s vibration damper. Read
the vehicle’s manual or contact the
manufacturer for the location of timing
marks on the engine. Also, refer to the
vehicle service manual or contact the
manufacturer for the timing specications
for the particular engine.
When to check timing
The instant that the spark plug
res is determined by the opening of the
distributor ignition breaker points and will
change any time the point gap or dwell
angle is changed. Normal wear on the
breaker point rubbing block will change the
dwell and effect the timing.
Most late model vehicles are
equipped with “breakerless electronic
ignition systems” and will not allow
a change in timing, because there are
no breaker points. The Timing Light
can still be used to note changes in the
timing caused by problems in the ignition
system or for resetting the timing when
components are changed (i.e. removed
and/or replaced).
Read the ENTIRE IMPORTANT
SAFETY INFORMATION section
at the beginning of this manual
including all text under
subheadings therein before set
up or use of this product.
Timing Light Hook Up
Note: These general instructions will
not apply to all engine designs
and/or vehicles. Consult engine
manufacturer’s service instructions
which supersede these instructions.
Locate the engine’s timing mark 1.
by referring to the vehicle’s
engine manual or contacting the
manufacturer. Refer to the vehicle’s
manual or contact the manufacturer
for the timing specications of the
engine being tested.
Start the engine and run for 5-15 2.
minutes until normal operating
temperature is reached.
Stop engine.3.
Turn the timing advance knob on the 4.
back of the timing light to 0°.
If the vehicle specications and 5.
instructions require it, locate the
vacuum line that attaches to the
ignition distributor vacuum advance
and disconnect the line and plug the
end of it. A golf tee or small pencil
may be used to plug the line.
Spark Plug
Clamp
#1 Spark
Plug
6. Connect the timing light to the 12 V
Battery, and connect the Spark Plug
Clamp to the Spark Plug Wire as
shown above. The spark plug clamp
must be connected with the arrow on
the clamp pointing towards the spark
plug.
Start the engine and operate it at idle 7.
speed.
8. WARNING! Be careful working
around the engine while the engine
is running. Moving belts and
the fan can cause severe injury
if contacted. Metal engine parts
release tremendous heat. Do not
make contact with any part of the
engine.
Note: The Spark Plug Clamp is fragile
and may break if dropped or struck
sharply.
Squeeze the trigger on the timing 9.
light and direct the ash onto the
engine timing marks to obtain a
reading. Compare the reading from
the timing mark to the reading in the
With the Engine stopped, loosen the 1.
bolt that locks down the distributor,
but do not fully remove it. It should
be loose enough so that you can
rotate the distributor back and forth.
Do not over-loosen the bolt or allow
the distributor to move on its own.
Start the engine and run until it 2.
reaches the standard operating
temperature.
FIGURE 1
Tighten the distributor lock down bolt 5.
using care not to change the position
of the distributor.
Start the engine and recheck the 6.
timing. If the timing is incorrect, the
distributor may have moved while
bolting it down. Reset the timing.
If you have no other tests to perform 7.
with the Timing Light, turn off the
engine and reconnect the vacuum
line. If you have further tests, rst
check to see if the vacuum line needs
to be connected for those tests.
Testing Centrifugal Advance
With the timing light still connected 1.
and the vacuum line still not attached,
speed the engine up slowly to the
manufacturer’s specied speed for
this test (often 2000 RPM) and watch
the timing mark.
3. Direct the beam from the Timing
Light at the timing marks and slowly
rotate the distributor in very small
increments. Rotate the distributor
either right or left until the timing
lines1 are lined up (in line with the
pointer). (See FIGURE 1)
Stop the engine.4.
1 Many vehicles have two timing marks:
One at TDC and another at 10° before
TDC.
REV 07h, 09f, 09g
The timing mark should move 2.
steadily, without jumping.
(See FIGURE 1)
If the mark stays stationary or moves 3.
erratically, the Centrifugal Advance
(or other automatic timing advances)
should be repaired by a certied
mechanic.
Turn the timing advance knob on the 4.
back of the timing light up slowly until
the timing mark moves to TDC or 0.
The reading on the timing advance 5.
scale indicates the amount of
centrifugal advance. Compare with
vehicle service manual.
this test (often 2000 RPM) and leave
the vacuum line detached from the
distributor.
Aim the Timing Light at the timing 2.
marks and turn the timing advance
knob on the back of the timing light
up slowly until the timing mark moves
to TDC or 0.
Connect the vacuum line to the 3.
distributor.
If the timing mark stays still, the 4.
trouble could be a plugged line,
a leaky diaphragm, or a frozen
distributor plate. See a certied
mechanic if the mark doesn’t move.
Read the amount of vacuum advance 5.
from the timing marks on the engine.
Compare with vehicle service
manual.
This test is done after the timing has 1.
been set and the timing light lines up
with the reference pointer for cylinder
number 1.
4 Cylinder
#1 Cylinder
Opposite
Cylinder
3
1
6 Cylinder
4
4
2
#1 Cylinder
Opposite
Cylinder
16
325
8 Cylinder
547
Opposite
Cylinder
62
31
8
#1 Cylinder
Note: The opposite cylinder is opposite
the #1 Cylinder on Distributor Cap.
REV 07h, 09g
FIGURE 3
2. Connect the Timing Light to the
spark plug wire directly opposite (180
degrees) from the number 1 cylinder
on the distributor cap.
(See FIGURE 3)
Start the engine and aim the Timing 3.
Light towards the timing mark. The
reading should be the same as when
the Timing Light was connected to
the number 1 cylinder wire. If not,
the probable cause is a worn out
distributor cam, bushing, or bearing,
or bent distributor shaft. Contact
The Timing Light can be used to test 1.
the timing on any combustion engine
that utilizes an impulse or magneto
ignition, such as motorcycles, lawn
mowers, or outboard motors. If the
product does not have a 12 V battery
then use an external battery.
Connect a ground from the external 2.
battery’s Negative Post to the engine.
Connect the red clip of the Timing 3.
light to the Positive Terminal of the
Battery and the black clip to the
Negative Terminal of the Battery.
Connect the Spark Plug Clamp of the
Timing Light to the spark plug wire
with the arrow pointing towards the
spark plug.
Rotary Engine Timing
1. Connect the red and black power
leads to the battery. Connect the
Spark Plug Clamp to the wire for the
leading spark plug on the front rotor
housing.
Start engine and run it at idle speed.2.
3. Aim the Timing Light at the timing
indicator pin of the front cover.
Loosen the distributor locking nuts 4.
and rotate the leading side distributor
body until the timing mark on the
eccentric shaft pulley is in line with
the timing indicator pin.
Tighten locking nuts and recheck 5.
timing.
Repeat this process to set the trailing 6.
side distributor timing.
explained in this manual
must be performed only by a
qualied technician.
TO PREVENT
SERIOUS INJURY
FROM SHOCK OR FIRE:
Disconnect from the vehicle
battery before performing any
inspection, maintenance, or
cleaning procedures.
TO PREVENT SERIOUS
INJURY FROM TOOL
FAILURE:
Do not use damaged
equipment. If abnormal noise
or vibration occurs, have the
problem corrected before
further use.
Bulb Cover (4)
Rubber
Sleeve (3)
Xenon Bulb
1. Remove Rubber Sleeve (3) from
nozzle of the Timing Light.
Remove the Bulb Cover (4).2.
The Xenon Bulb may develop a black 3.
spot around the anode; this is normal.
If the bulb turns completely black
however, it should be replaced.
Cleaning, Maintenance, and
Lubrication
BEFORE EACH USE,1. inspect the
general condition of the tool. Check
for loose hardware, misalignment
or binding of moving parts, cracked
or broken parts, damaged electrical
wiring, and any other condition that
may affect its safe operation.
AFTER USE,2. wipe external surfaces
of the tool with clean cloth.
Contact a certied technician to 4.
replace the Xenon Bulb.
THE MANUFACTURER AND/OR DISTRIBUTOR HAS PROVIDED THE PARTS LIST AND ASSEMBLY
DIAGRAM IN THIS MANUAL AS A REFERENCE TOOL ONLY. NEITHER THE MANUFACTURER OR
DISTRIBUTOR MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND TO THE BUYER THAT
HE OR SHE IS QUALIFIED TO MAKE ANY REPAIRS TO THE PRODUCT, OR THAT HE OR SHE IS
QUALIFIED TO REPLACE ANY PARTS OF THE PRODUCT. IN FACT, THE MANUFACTURER AND/OR
DISTRIBUTOR EXPRESSLY STATES THAT ALL REPAIRS AND PARTS REPLACEMENTS SHOULD BE
UNDERTAKEN BY CERTIFIED AND LICENSED TECHNICIANS, AND NOT BY THE BUYER. THE BUYER
ASSUMES ALL RISK AND LIABILITY ARISING OUT OF HIS OR HER REPAIRS TO THE ORIGINAL
PRODUCT OR REPLACEMENT PARTS THERETO, OR ARISING OUT OF HIS OR HER INSTALLATION
OF REPLACEMENT PARTS THERETO.
Harbor Freight Tools Co. makes every effort to assure that its products meet high
quality and durability standards, and warrants to the original purchaser that this product
is free from defects in materials and workmanship for the period of 90 days from the date
of purchase. This warranty does not apply to damage due directly or indirectly, to misuse,
abuse, negligence or accidents, repairs or alterations outside our facilities, criminal activity,
improper installation, normal wear and tear, or to lack of maintenance. We shall in no event
be liable for death, injuries to persons or property, or for incidental, contingent, special
or consequential damages arising from the use of our product. Some states do not allow
the exclusion or limitation of incidental or consequential damages, so the above limitation
of exclusion may not apply to you. THIS WARRANTY IS EXPRESSLY IN LIEU OF ALL
OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF
MERCHANTABILITY AND FITNESS.
To take advantage of this warranty, the product or part must be returned to us with
transportation charges prepaid. Proof of purchase date and an explanation of the complaint
must accompany the merchandise. If our inspection veries the defect, we will either
repair or replace the product at our election or we may elect to refund the purchase price
if we cannot readily and quickly provide you with a replacement. We will return repaired
products at our expense, but if we determine there is no defect, or that the defect resulted
from causes not within the scope of our warranty, then you must bear the cost of returning
the product.
This warranty gives you specic legal rights and you may also have other rights which
vary from state to state.
3491 Mission Oaks Blvd. • PO Box 6009 • Camarillo, CA 93011 • (800) 444-3353