Pinpoint Test A : DTC P185A:00

WARNING: This page is about a different car, the 2019 Ford F-550 Super Duty, 2019 Ford F-450 Super Duty, 2019 Ford F-350 Super Duty, and 2019 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Make sure the battery is fully charged before carrying out this pinpoint test.

Refer to Four Wheel Drive Systems for schematic and connector information.

Normal Operation and Fault Conditions

When the ELDMSS is engaged to lock the rear differential, the ELDMSS opens allowing the voltage being monitored by the TCCM to go high. When the TCCM senses the voltage is high it activates the ELD. The TCCM sends a message to the IPC via the HS-CAN requesting the IPC illuminate the ELD message center indicator.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
TCCM P185A:00	Differential Lock-Up Input Switch Circuit High: No Sub Type Information	If the ELD is functioning normally, the differential immediately locks when the ELDMSS is activated and the ELD operating conditions are qualified. This DTC only displays during the self-test function.

Possible Sources

Wiring, terminals or connectors
TCCM
MSS

A1 CHECK FOR TCCM DTCS

NOTE: Failure to place the ELD MSS in OFF position prior to carrying out a self-test of the TCCM results in the false setting of DTC P185A:00.
- Ignition ON.
- Set the ELDMSS to OFF.
- Enter the following diagnostic mode: TCCM Self-Test.
Are any DTCs present?

Yes If only DTC P185A:00 is retrieved, GO to A2 For any other DTCs, REFER to the DTC Chart.

No IDENTIFY the customer concern and GO to Symptom Chart: ELD.

A2 CHECK THE LOCKER MODE SWITCH CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.

Disconnect TCCM C2371A.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2371A-15	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes

GO to A3

GO to A4

A3 CHECK THE LOCKER MODE SWITCH CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.

Disconnect MSS C284.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2371A-15	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR circuit. CLEAR the DTCs.

No	INSTALL a new MSS

A4 CHECK THE LOCKER MODE SWITCH CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C284-5	Courtesy of FORD MOTOR COMPANY	C2371A-15

Is the resistance less than 3 ohms?

Yes

GO to A5

No	REPAIR the circuit.

A5 CHECK THE MSS

Connect MSS Switch C284.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2371A-15	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance between 24 - 24.5 ohms with the ELDMSS de-activated and greater than 10, 000 ohms with the ELDMSS activated?

Yes

GO to A6

No	INSTALL a new MSS. REFER to: Mode Select Switch (MSS) .

A6 CHECK THE LOCKER MODE SWITCH GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C284-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes

GO to A7

No	REPAIR the circuit.

A7 CHECK FOR CORRECT TCCM OPERATION

Ignition OFF.

Disconnect and inspect all TCCM connectors.

Check for the following:
- 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 all TCCM connectors. Make sure they seat and latch correctly.

Operate the system and verify the concern is still present.

Is the concern still present?

Yes	INSTALL a new TCCM. REFER to: Transfer Case Control Module (TCCM) .

No	The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. ADDRESS the root cause of the connector or pin issues.