Actron SunPro CP7678, Operating Instructions Manual

250V MAX

15A MAX

FUSED

COM

DC

15A

20M

200
    K

20K

2K

200

8CYL

6CYL

TACH

X10

5CYL

4CYL

8CYL

OHMS

15

A

27

Measuring Fuel Injector Resistance

Fuel injectors are similar to solenoids. They
contain a coil that is switched ON and OFF by
the vehicle computer. This test measures the
resistance of this coil to make sure it is not an
open circuit. Shorted coils can also be de-
tected if the specific manufacturer resistance
of the fuel injector is known.

Fig. 29

Typical Fuel

Injector

Black

Red

Test Procedure (see Fig. 29):

1. Insert BLACK test lead into COM test

lead jack.

2. Insert RED test lead into  

 test

lead jack.

3. Turn multimeter rotary switch to 200

Ω

range.

Touch RED and BLACK multimeter leads
together and view reading on display.

Display should read typically 0.2 - 1.5

Ω

.

If display reading was greater than 1.5

Ω

,

check both ends of test leads for bad
connections. If bad connections are found,
replace test leads.

4. Disconnect wiring harness from fuel

injector - Refer to vehicle service manual
for procedure.

5. Connect RED and BLACK test leads

across fuel injector pins.

Make sure you connect test leads across
fuel injector and not the wiring harness.

6. Turn multimeter rotary switch to de-

sired OHM range.

If the approximate resistance is unknown,
start at the largest OHM range and de-
crease to the appropriate range as re-
quired. (see Setting the Range on page 6)

7. View reading on display - Note range

setting for correct units.

• If display reading is 10

Ω

 or less, subtract

test lead resistance found in Step 3 from
above reading.

• Compare reading to manufacturers speci-

fications for fuel injector coil resistance.

• This information is found in vehicle ser-

vice manual.

8. Test Results

Good Fuel Injector resistance:

  Resistance

of fuel injector coil is within manufacturers
specifications.

Bad Fuel Injector resistance:

  Resistance

of fuel injector coil is not within manufac-
turers specifications.

NOTE:  If resistance of fuel injector coil is
within manufacturers specifications, the
fuel injector could still be defective. It is
possible that the fuel injector is clogged or
dirty and that is causing your driveability
problem.