The purpose
for the followng procedure is to show different methods of checking
the voltage of a circuit. When diagnosing a DTCs it might be necessary
to verify that proper voltage is on a circuit or that a circuit is
not shorted high. Below are four examples of checking the voltage
in a circuit.
Test Procedures
CHECKING FOR VOLTAGE ON A CIRCUIT
CHECKING FOR A SHORT
TO BATTERY VOLTAGE USING A MULTIMETER
CHECKING FOR A SHORT
TO IGNITION VOLTAGE USING A MULTIMETER
CHECKING FOR A SHORT
TO VOLTAGE USING A 12-VOLT TEST LIGHT
1.
CHECKING FOR
VOLTAGE
NOTE:
The connector displayed
in the graphics are only an example.
1.
Turn the ignition
off.
2.
Disconnect the
wire harness connector of the component that is being tested.
NOTE:
Check connectors -
Clean/repair as necessary.
3.
At this time leave
all in-line connectors connected.
4.
Use a multimeter
set to measure DC voltage.
5.
Connect the ground
lead of the meter to a known good ground circuit.
6.
Use the positive
lead of the multimeter and probe the circuit you are checking for
voltage.
7.
Ignition on, engine
not running.
Is the
voltage within specifications for this circuit?
Yes
The circuit is functioning
properly or the condition that originally caused the open or short
may not be present at this time. Continue to measure the voltage and
wiggle the wire harness and connectors while checking for an intermittent
open or short.
Use the wiring application
as a guide to trace the circuits and look for any in-line connectors
where the short could occur intermittently.
Look for any chafed,
pierced, pinched, or partially broken wires.
Look for broken, bent,
pushed out or corroded terminals. Verify that there is good pin to
terminal contact in the related wire harness connectors.
Perform any Technical
Service Bulletins that may apply.
No
Repair the open or
short to ground in the circuit. Use the wiring application as a guide
to trace the circuits and look for any in-line connectors where the
short could occur.
One way to help isolate
the open or short is to disconnect any in-line connectors that the
circuit being checked runs through and check for the voltage again.
If the voltage is present, the open or short is on the other side
of the in-line connector.
2.
CHECKING FOR
A SHORT TO BATTERY VOLTAGE USING A MULTIMETER
1.
Turn the ignition
off.
2.
Disconnect the
wire harness connectors of the components that contain the circuit
that is suspected as having a short.
NOTE:
Check connectors -
Clean/repair as necessary.
3.
At this time leave
all in-line connectors connected.
4.
With all the component
wire harness connectors disconnected, use a multimeter set to measure
DC voltage.
5.
Connect the ground
lead of the meter to a known good ground circuit.
6.
Use the positive
lead of the multimeter and probe the circuit you suspect has a short.
Is there
any voltage present?
Yes
Repair the short to
battery voltage. Use the wiring application as a guide to trace the
circuits and look for any in-line connectors where the short could
occur.
One way to help isolate
the short is to disconnect any in-line connectors that the circuit
being checked runs through and measure for the short again. If the
short goes away, the short is on the other side of the in-line connector.
No
The circuit is not
shorted to voltage or the condition that originally caused the short
may not be present at this time. Continue to measure the voltage and
wiggle the wire harness to check for an intermittent short.
NOTE:
By disconnecting the
wire harness connectors you may have eliminated the source of the
voltage causing the short. Use the wiring application as a guide,
check to see if there are any battery circuits in the same wire harness
as the circuit you are testing. It is necessary to check for a short
to those circuits using an Ohm meter. (Refer to 29 - Non-DTC Diagnostics/Circuit
Testing Procedures - Standard Procedure)
and perform the Check
for a Short Between Multiple Circuits diagnostic procedure.
Use the wiring application
as a guide to trace the circuits and look for any in-line connectors
where the short could occur intermittently.
Look for any chafed,
pierced, pinched, or partially broken wires.
Look for broken, bent,
pushed out or corroded terminals. Verify that there is good pin to
terminal contact in the related wire harness connectors.
Perform any Technical
Service Bulletins (TSBs) that may apply.
3.
CHECKING FOR
A SHORT TO IGNITION VOLTAGE OR TO CHECK FOR VOLTAGE ON A CIRCUIT USING
A MULTIMETER
1.
Turn the ignition
off.
2.
Disconnect the
wire harness connectors of all components that contain the circuits
that are suspected as being shorted.
3.
At this time leave
all in-line connectors connected.
4.
With all the component
wire harness connectors disconnected, use a multimeter set to measure
DC voltage.
5.
Connect the ground
lead of the meter to a known good ground circuit.
6.
Use the positive
lead of the multimeter and probe the circuit you suspect has a short.
7.
Ignition on, engine
not running.
Is any
voltage present?
Yes
Repair the short to
ignition voltage. Use the wiring application as a guide to trace the
circuits and look for any in-line connectors where the short could
occur.
One way to help isolate
the short is to disconnect any in-line connectors that the circuit
being checked runs through and check for the short again. If the short
goes away, the short is on the other side of the in-line connector.
No
The circuit is not
shorted to voltage or the condition that originally caused the short
may not be present at this time. Continue to measure the voltage and
wiggle the wire harness to check for an intermittent short.
NOTE:
By disconnecting the
wire harness connectors you may have eliminated the source of the
voltage causing the short. Use the wiring application as a guide,
check to see if there are any battery circuits in the same wire harness
as the circuit you are testing. It is necessary to check for a short
to those circuits using an Ohm meter. (Refer to 29 - Non-DTC Diagnostics/Circuit
Testing Procedures - Standard Procedure)
and perform the Check
for a Short Between Multiple Circuits diagnostic procedure.
Use the wiring application
as a guide to trace the circuits and look for any in-line connectors
where the short could occur intermittently.
Look for any chafed,
pierced, pinched, or partially broken wires.
Look for broken, bent,
pushed out or corroded terminals. Verify that there is good pin to
terminal contact in the related wire harness connectors.
Perform any Technical
Service Bulletins (TSBs) that may apply.
4.
CHECKING FOR
A SHORT TO VOLTAGE USING A 12-VOLT TEST LIGHT
1.
Turn the ignition
off.
2.
Disconnect the
wire harness connectors of all components that contain the circuits
that are suspected as being shorted.
NOTE:
Check connectors -
Clean/repair as necessary.
3.
At this time leave
all in-line connectors connected.
NOTE:
Before inspecting any
circuits, first test the 12-volt test light. Connect the 12-volt test
light to battery ground or to any other known good ground. Touch the
lead of the test light to Battery +. If the test light is good, it
should illuminate brightly.
4.
Connect the 12-volt
test light to a known good ground circuit.
5.
Use the lead of
the test light and carefully probe the circuit you suspect has a short.
WARNING:
When the engine is operating, do
not stand in direct line with the fan. Do not put your hands near
the pulleys, belts or fan. Do not wear loose clothing. Failure to
follow these instructions may result in possible serious or fatal
injury.
6.
First, check with
the ignition off , next with the ignition on, and lastly while cranking
the engine.
Does
the test light illuminate brightly?
Yes
Repair the short to
voltage. Use the wiring application as a guide to trace the circuits
and look for any in-line connectors where the short could occur.
One way to help isolate
the short is to disconnect any in-line connectors that the circuit
being checked runs through and check for the short again. If the short
goes away, the short is on the other side of the in-line connector.
No
The circuit is not
shorted to voltage or the condition that originally caused the short
may not be present at this time. Continue to measure the resistance
and wiggle the wire harness to check for an intermittent short.
NOTE:
By disconnecting
the wire harness connectors you may have eliminated the source of
the voltage causing the short. Use the wiring application as a guide,
check to see if there are any battery circuits in the same wire harness
as the circuit you are testing. It is necessary to check for a short
to those circuits using an Ohm meter. (Refer to 29 - Non-DTC Diagnostics/Circuit
Testing Procedures - Standard Procedure)
and perform the Check
for a Short Between Multiple Circuits diagnostic procedure.
Use the wiring application
as a guide to trace the circuits and look for any in-line connectors
where the short could occur intermittently.
Look for any chafed,
pierced, pinched, or partially broken wires.
Look for broken, bent,
pushed out or corroded terminals. Verify that there is good pin to
terminal contact in the related component and wire harness connectors.
Perform any Technical
Service Bulletins (TSBs) that may apply.
