Harbor Freight Tools 97577 Manual Download Page 1

WARNING

To prevent death, serious injury and 

vehicle damage:

NEVER operate vehicle engine 

1. 

inside garage, EVEN IF doors and 

windows are open.

WARNING: This product contains 

2. 

lead, which is a chemical known to 

the State of California to cause cancer 

and birth defects or other reproductive 

harm. (California Health & Safety 

Code § 25249.5, 

et seq.

)

Wear ANSI-approved safety goggles 

3. 

and heavy-duty work gloves during 

use.

Keep tester and self clear of hot or 

4. 

moving engine parts.
Do not connect ground clamp to 

5. 

carburetor or fuel lines.
Inspect before use; do not use if parts 

6. 

loose or damaged.
Use for intended purposes only.

7. 

Read vehicle’s service manual and 

8. 

follow directions and precautions for 

use.

Functions:

The ChECk LIGhT illuminates to show 

a spark passing through it.

 

The wire from the coil is attached to the 

metal post on the bulb end.  The black 

boot leads to the spark plug/ground.

The ExTENsIoN is used to connect the 

spark checker to recessed plugs.

 

The black boot of the check light connects 

to the exposed metal tip of the extension. 

The opposite end of the extension con-

nects to the spark plug.

The GRouNd CLAmp is used to con-

nect the check light to a grounded part 

of the engine.

 

The black boot of the check light connects 

to the exposed metal tip of the clamp.  The 

alligator clamp connects to a grounded 

portion of the engine.

Test Results

Result

Likely Cause

Engine

Bulb

Does not start

Flashes

Fuel system fault

Does not start

Does not flash

Ignition fault

Starts

Flashes weak/inconsistent

Ignition fault

Bulb Replacement:

Cap

Base

Bulb/spring  

Assembly

1.  Unthread the Cap from the Base of the 

Check Light and remove the Bulb/Spring 

Assembly.
Remove the Sleeve from the Spring. Re-

2. 

move the old Bulb and dispose of properly.

Bulb

sleeve

spring

3.  Insert a new GE part NE51H (B2A) or 

equivalent Bulb into the Spring.  Insert the 

Bulb, cover first, into the wider end of the 

Spring.
Place the Sleeve over the base of the Bulb 

4. 

and Spring Combination.
Insert the Bulb and Spring into the Cap.  

5. 

Reassemble the Cap onto the Base.
Wash hands thoroughly after assembly; 

6. 

Bulb and Bulb Connector contain lead.

distributed exclusively by harbor Freight Tools.

 

sAVE ThEsE INsTRuCTIoNs.

08b

 

Made in China.

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