Infiniti Q45. Manual - part 378

POWER SUPPLY AND GROUND CIRCUIT

EC-151

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7. 

CHECK ECM POWER SUPPLY CIRCUIT-II

1.

Disconnect ECM relay.

2.

Check voltage between ECM relay terminals 2, 5 and ground
with CONSULT-II or tester.

OK or NG

OK

>> GO TO 9.

NG

>> GO TO 8.

8. 

DETECT MALFUNCTIONING PART

Check the following.

●

10A fuse

●

20A fuse

●

Fuse block (J/B) No. 2 connector E215

●

Fuse, fusible link and relay block (J/B) connector E3

●

Harness for open or short between ECM relay and battery

>> Repair open circuit or short to ground or short to power in harness or connectors.

9. 

CHECK OUTPUT SIGNAL CIRCUIT FOR OPEN AND SHORT

1.

Check harness continuity between ECM terminal 111 and ECM relay terminal 1.
Refer to Wiring Diagram.

2.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 11.

NG

>> GO TO 10.

10. 

DETECT MALFUNCTIONING PART

Check the following.

●

Harness connectors M135, F105

●

Fuse block (J/B) No. 2 connector M143

●

Harness for open or short between ECM relay and ECM

>> Repair open circuit or short to ground or short to power in harness or connectors.

PBIB0040E

Voltage: Battery voltage

PBIB0071E

Continuity should exist.

EC-152

POWER SUPPLY AND GROUND CIRCUIT

11. 

CHECK ECM RELAY

Refer to 

EC-155, "Component Inspection"

 .

OK or NG

OK

>> Go to 

EC-731, "IGNITION SIGNAL"

 .

NG

>> Replace ECM relay.

12. 

CHECK ECM POWER SUPPLY CIRCUIT-III

1.

Turn ignition switch OFF and wait at least 10 seconds.

2.

Turn ignition switch ON and then OFF.

3.

Check voltage between ECM terminals 119, 120 and ground
with CONSULT-II or tester.

OK or NG

OK

>> GO TO 18.

NG (Battery voltage does not exist.)>>GO TO 13.
NG (Battery voltage exists for more than a few seconds.)>>GO TO 15.

13. 

CHECK ECM POWER SUPPLY CIRCUIT-IV

1.

Disconnect ECM relay.

2.

Check voltage between ECM relay terminal 7 and ground with
CONSULT-II or tester.

OK or NG

OK

>> GO TO 15.

NG

>> GO TO 14.

Voltage:

After turning ignition switch OFF, battery 
voltage will exist for a few seconds, then 
drop approximately 0V.

PBIB1630E

PBIB0040E

Voltage:

Battery voltage

PBIB0074E

POWER SUPPLY AND GROUND CIRCUIT

EC-153

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14. 

DETECT MALFUNCTIONING PART

Check harness for open or short between ECM relay and 10A fuse

>> Repair open circuit or short to ground or short to power in harness or connectors.

15. 

CHECK ECM POWER SUPPLY CIRCUIT-V

1.

Disconnect ECM harness connector.

2.

Check harness continuity between ECM terminals 119, 120 and ECM relay terminal 6.
Refer to Wiring Diagram.

3.

Also check harness for short to ground and short to power.

OK or NG

OK

>> GO TO 17.

NG

>> GO TO 16.

16. 

DETECT MALFUNCTIONING PART

Check the following.

●

Harness connectors M135, F105

●

Fuse block (J/B) No. 2 connector M143

●

Harness for open or short between ECM and ECM relay

>> Repair open circuit or short to ground or short to power in harness or connectors.

17. 

CHECK ECM RELAY

Refer to 

EC-155, "Component Inspection"

 .

OK or NG

OK

>> GO TO 18.

NG

>> Replace ECM relay.

18. 

CHECK GROUND CONNECTIONS

1.

Turn ignition switch OFF.

2.

Loosen and retighten three ground screws on the body.
Refer to 

EC-154, "Ground Inspection"

 .

OK or NG

OK

>> GO TO 19.

NG

>> Repair or replace ground connections.

Continuity should exist.

PBIB2417E

EC-154

POWER SUPPLY AND GROUND CIRCUIT

19. 

CHECK ECM GROUND CIRCUIT FOR OPEN AND SHORT-II

1.

Disconnect ECM harness connector.

2.

Check harness continuity between ECM terminals 1, 115, 116 and ground.
Refer to Wiring Diagram.

3.

Also check harness for short to power.

OK or NG

OK

>> GO TO 21.

NG

>> GO TO 20.

20. 

DETECT MALFUNCTIONING PART

Check the following.

●

Harness connectors F32, E32

●

Harness for open or short between ECM and ground

>> Repair open circuit or short to power in harness or connectors.

21. 

CHECK INTERMITTENT INCIDENT

Refer to 

EC-145, "TROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENT"

 .

>> INSPECTION END

Ground Inspection 

NBS001RK

Ground connections are very important to the proper operation of electrical and electronic circuits. Ground
connections are often exposed to moisture, dirt and other corrosive elements. The corrosion (rust) can
become an unwanted resistance. This unwanted resistance can change the way a circuit works.
Electronically controlled circuits are very sensitive to proper grounding. A loose or corroded ground can drasti-
cally affect an electronically controlled circuit. A poor or corroded ground can easily affect the circuit. Even
when the ground connection looks clean, there can be a thin film of rust on the surface.
When inspecting a ground connection follow these rules:

●

Remove the ground bolt or screw.

●

Inspect all mating surfaces for tarnish, dirt, rust, etc.

●

Clean as required to assure good contact.

●

Reinstall bolt or screw securely.

●

Inspect for “add-on” accessories which may be interfering with the ground circuit.

●

If several wires are crimped into one ground eyelet terminal, check for proper crimps. Make sure all of the
wires are clean, securely fastened and providing a good ground path. If multiple wires are cased in one
eyelet make sure no ground wires have excess wire insulation.

Continuity should exist.