Download Powertrain Control Module (PCM ) Power Relay

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Year = 2011
Model = Mustang
Engine = 5.0L
VIN =
IDS Version = Not Available
Powertrain Control Module (PCM ) Power Relay
Note:
The IGN START/RUN and ground circuits, or the B+ and VPWR circuits may be reversed in the
harness connector. Refer to the Wiring Diagrams Manual Electronic Engine Control Cell for
schematic and connector information.
This pinpoint test is intended to diagnose the following:
 harness circuits: B+ , IGN START/RUN , INJPWRM , ISP-R , PCMRC , VPWR and GND
 PCM power relay (12A646)
 PCM (12A650)
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INJ Connector
Harness Side
Circuit
VPWR (Vehicle Power)
Pin
2
Powertrain Control Module Power (PCM Power)
Relay Connector
Harness Side
Circuit
B+ (Battery Positive Voltage)
B+ (Battery Positive Voltage)
PCMRC (PCM Relay Control)
VPWR (Vehicle Power)
Component side
Pin
30
85
86
87
PCM Connector - For PCM connector views or
reference values, refer to Section 6.
Harness Side
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B1 : CHECK FOR DIAGNOSTIC TROUBLE CODES ( DTCS)
 Are DTCs P0685, P0686, P0687, P0689, P0690, P1793, P2510 or U300C present?
Yes
For DTCs P0685, P0686, P0687, P0690, P1793 or
U300C, Go to B8.
For DTCs P0689 and P2510, Go to B12.
No
For all other symptoms without DTCs,
Go to B2.
B2 : CHECK THE B+ AND IGN START/RUN VOLTAGE TO PCM POWER RELAY
 Ignition OFF.
 PCM Power Relay connector disconnected.
 Ignition ON, engine OFF.

Measure the voltage between:
(+)
PCM Power Relay Connector, Harness Side
B+ - Pin 30
B+ - Pin 85
IGN START/RUN

(-)
Ground
Ground
Ground
Are the voltages greater than 10 V?
Yes
Go to B3.
No
REPAIR the open circuit.
Clear the PCM DTCs. REPEAT the self-test.
B3 : CHECK THE PCMRC CIRCUIT FOR AN OPEN IN THE HARNESS
 Ignition OFF.
 PCM connector disconnected.

Measure the resistance between:
(+)
PCM Power Relay Connector, Harness Side
PCMRC - Pin 86

(-)
PCM Connector, Harness Side
PCMRC - Pin B38
Is the resistance less than 5 Ohm?
Yes
Go to B4.
No
REPAIR the open circuit.
Clear the PCM DTCs. REPEAT the self-test.
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
Ignition ON, engine OFF.

Measure the voltage between:
(+)
PCM Connector, Harness Side
PCMRC - Pin B38

(-)
Ground
Is any voltage present?
Yes
REPAIR the short circuit.
Clear the PCM DTCs. REPEAT the self-test.
No
Go to B5.
B5 : CHECK THE ISP-R VOLTAGE AT THE PCM HARNESS CONNECTOR
 Ignition OFF.
 PCM Power Relay connector connected.
 Ignition ON, engine OFF.

Measure the voltage between:
(+)
PCM Connector, Harness Side
ISP-R - Pin B42

(-)
Ground
Is the voltage greater than 10 V?
Yes
Go to B7.
No
REPAIR the open circuit.
Clear the PCM DTCs. REPEAT the self-test.
B6 : CHECK THE PCM POWER RELAY GROUND CIRCUIT FOR AN OPEN

Measure the voltage between:
(+)
PCM Power Relay Connector, Harness Side
B+ - Pin 30
B+ - Pin 85

(-)
PCM Power Relay Connector, Harness Side
GND
GND
Are the voltages greater than 10 V?
Yes
Go to B7.
No
REPAIR the open circuit.
Clear the PCM DTCs. REPEAT the self-test.
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VPWR - Pin 87

VPWR - Pin B68
Are the resistances less than 5 Ohm?
Yes
INSTALL a new PCM Power relay.
Clear the PCM DTCs. REPEAT the self-test.
No
REPAIR the open circuit.
Clear the PCM DTCs. REPEAT the self-test.
B8 : CHECK THE PCMRC CIRCUIT FOR A SHORT TO GROUND IN THE HARNESS
 Ignition OFF.
 PCM Power Relay connector disconnected.
 PCM connector disconnected.

Measure the resistance between:
(+)
PCM Connector, Harness Side
PCMRC - Pin B38

(-)
Ground
Is the resistance greater than 10 kOhm?
Yes
Go to B9.
No
REPAIR the short circuit.
Clear the PCM DTCs. REPEAT the self-test.
B9 : CHECK THE ISP-R CIRCUIT FOR A SHORT TO VOLTAGE IN THE HARNESS
 Ignition OFF.

Measure the voltage between:
(+)
PCM Connector, Harness Side
ISP-R - Pin B42

(-)
Ground
Is any voltage present?
Yes
REPAIR the short circuit.
Clear the PCM DTCs. REPEAT the self-test.
No
Go to B10.
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B11 : CHECK THE INJPWR_M PID
 Ignition OFF.
 PCM Power Relay connector connected.
 PCM connector connected.
 Ignition ON, engine OFF.
 Access the PCM and monitor the INJPWR_M (VOLT) PID.
 Record the INJPWR_M PID value
 Ignition OFF.
 Record the INJPWR_M PID value
 Is the INJPWR_M PID voltage reading above 10 V with key ON and 0 V with the key OFF?
Yes
Go to B13.
No
REPAIR the circuit.
Clear the PCM DTCs. REPEAT the self-test.
B12 : CHECK THE ISP-R VOLTAGE AT THE PCM HARNESS CONNECTOR
 Ignition OFF.
 PCM connector disconnected.
 Ignition ON, engine OFF.

Measure the voltage between:
(+)
PCM Connector, Harness Side
ISP-R - Pin B42

(-)
Ground
Is the voltage greater than 10 V?
Yes
Go to B13.
No
REPAIR the open circuit.
Clear the PCM DTCs. REPEAT the self-test.
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