Pinpoint Test C : P0620

WARNING: This page is about a different car, the 2016 Ford Expedition. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Make sure battery voltage is greater than 12.2 volts prior to and during this pinpoint test.

NOTE: Do not have a battery charger attached during vehicle testing.

C1 PERFORM INSPECTION AND VERIFICATION
- Perform the Inspection and Verification procedure in this article.
Was an obvious cause for an observed or reported concern found?

Yes CORRECT conditions as necessary.

No GO to C2.

C2 CHECK THE GENERATOR CONNECTIONS

Ignition OFF.

Disconnect and inspect all generator connectors.

Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary

Connect the generator connectors. Make sure they seat, latch correctly and are tightened to specification. REFER to Generator and Regulator .

Measure and record:

Positive Lead	Measurement / Action	Negative Lead
Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY

Measure:

Positive Lead	Measurement / Action	Negative Lead
C102A-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage within 0.5 volt of recorded battery voltage?

Yes	GO to C3.
No	VERIFY BJB MEGA fuse (350 A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM Electrical Wiring Diagram Introduction to identify the Possible Sources of the circuit short.

C3 CHECK THE VOLTAGE DROP IN THE B+ CIRCUIT

Start the engine.

With the engine running at idle, headlamps on and blower on high, measure:

Positive Lead	Measurement / Action	Negative Lead
C102A-1	Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY Battery Positive Post

Carry out a wiggle test of the generator wiring and connections while measuring voltage drop.

Is the voltage drop less than 0.5 volt?

Yes	GO to C4.
No	INSPECT and REPAIR any corrosion in the generator B+ circuit or positive battery cable connections.

C4 "A" SENSE CIRCUIT LOAD TEST

NOTE: The following step uses a test light to simulate normal circuit loads. Use only the test light recommended in the Special Tools table at the beginning of this article. To avoid connector terminal damage, use the Flex Probe Kit for the test light probe connection to the vehicle. Do not use the test light probe directly on any connector.

NOTE: This step puts a load on the "A" sense circuit. If there are corroded or loose connections, loading the circuit may help show the fault. A 250-350 mA incandescent 12-volt test lamp is required for this step. This circuit cannot be loaded correctly using an LED-style test lamp.

Ignition OFF.

Disconnect: Generator C102B .

Measure battery voltage and record:

Positive Lead	Measurement / Action	Negative Lead
Courtesy of FORD MOTOR COMPANY Battery Positive Post	Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY Battery Negative Post

Ignition ON.

Connect a 12-volt test lamp to ground to load the circuit.

With the meter and load connected to the circuit, perform a wiggle test on the generator harness.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C102B-3	Courtesy of FORD MOTOR COMPANY	Ground

Is the "A" sense voltage equal to battery voltage?

Yes	GO to C5.
No	VERIFY BJB fuse 26 (10A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the OEM Electrical Wiring Diagram Introduction to identify the Possible Sources of the circuit short.

C5 CHECK THE GENERATOR COMMAND CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.

Disconnect: PCM C175B .

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C102B-2	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit.
No	GO to C6.

C6 CHECK THE GENERATOR COMMAND CIRCUIT FOR A SHORT TO GROUND

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C102B-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes	GO to C7.
No	REPAIR the circuit.

C7 CHECK THE GENERATOR COMMAND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C175B-59	Courtesy of FORD MOTOR COMPANY	C102B-2

Is the resistance less than 3 ohms?

Yes	GO to C8.
No	REPAIR the circuit.

C8 COMPARE THE GENERATOR MONITOR (GENMON) AND GENERATOR COMMAND (GENCMD) PIDs

Ignition OFF.

Connect: PCM C175B .

Connect a fused jumper wire:

Positive Lead	Measurement / Action	Negative Lead
C102B-1	Courtesy of FORD MOTOR COMPANY	C102B-2

Start the engine.

Using a diagnostic scan tool, view the PCM PIDs.

Monitor the PCM PIDs GENMON and GENCMD while performing a wiggle test on the generator harness.

Do the PIDs read within 5% of each other?

Yes	REMOVE the fused jumper wire. INSTALL a new generator. REFER to Generator and Regulator .
No	REMOVE the fused jumper wire. GO to C9.

C9 CHECK FOR CORRECT PCM OPERATION

Ignition OFF.

Disconnect and inspect all PCM connectors.

Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary

Reconnect the PCM and generator connectors. Make sure they seat and latch correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any applicable TSBs. If a TSB exists for this concern, DISCONTINUE this test and FOLLOW the TSB instructions. If no TSBs address this concern, INSTALL a new PCM. REFER to Electronic Engine Controls .
No	The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.

Yes	CORRECT conditions as necessary.
No	GO to C2.