Visual Inspection and Diagnostic Pre-checks

WARNING: This page is about a different car, the 2020 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

Make sure BCM fuse 31 (10A) for the ATCM is OK.

CAUTION: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may cause damage to the connector.

Fig 1: All Terrain Control Module (ATCM) Connector - C3639

Courtesy of FORD MOTOR CO.

Harness Side

Circuit	Pin
B+ (Battery Positive Voltage) - SBP31	1 (WHITE/RED)
GND (Ground) - GD126	4 (BLACK/VIOLET)

Fig 2: Body Control Module-A (BCM-A) Connector - C2280A

Courtesy of FORD MOTOR CO.

Harness Side

Circuit

Fig 3: Drive Mode Switch Connector - C3685

Courtesy of FORD MOTOR CO.

Harness Side

Circuit	Pin
GND (Ground) - GD216	12 (BLACK/VIOLET)
SDM DWN-RT (Selectable Drive Mode Down Right) - CCD30	1 (BROWN/BLUE)
SDM UP-LT (Selectable Drive Mode Up Left) - CCD29	3 (BLUE)

Fig 4: Heating Ventilation Air Conditioning-B (HVAC-B) Module Connector - C228B

Courtesy of FORD MOTOR CO.

Harness Side

Circuit	Pin
SDM DWN-RT (Selectable Drive Mode Down Right) - CDD30	1 (BROWN/BLUE)
SDM UP-LT (Selectable Drive Mode Up Left) - CCD29	3 (BLUE)

OB1: CHECK FOR OTHER ABS MODULE DTCS

Put the ABS module in sleep mode by performing the following steps:
- With ALL doors closed, set the ignition from ON to OFF.
- Disconnect the diagnostic scan tool.
- Open the door, exit the vehicle and close the door.
- Wait a minimum of 90 seconds for the ABS module to enter sleep mode.
Ignition ON, engine OFF.
Carry out the ABS self-test.

Are any battery voltage or lost communication DTCs present in the ABS module?

Yes	No
DIANOSE all ABS module battery voltage and lost communication DTCs before diagnosing the selectable drive mode switch. GO to the ABS module DTC Chart.	Go to OB2.

OB2: DETERMINE SELECTABLE DRIVE MODE CAPABILITY

Press the Read Vehicle Information button to view the results of the modules communicating on the network.
Retrieve the continuous memory DTCs.

Is the vehicle equipped with an ATCM?

Yes	No
Go to OB13.	For Aviator, Go to OB7. For Corsair, Go to OB7. For Escape, Go to OB7. For Expedition without an ATCM and with a column mounted selector lever, Go to OB3. For Expedition without an ATCM and with a GSM, Go to OB17. For Explorer, Go to OB7. For F-150, Go to OB5. For F-Series Super Duty with a 6.2L or 7.3L engine, Go to OB5. For F-Series Super Duty with a 6.7L engine, Go to OB3. For Navigator without an ATCM and with a GSM, Go to OB17. For all others, Go to OB10.

Yes

Go to OB13.

For Aviator, Go to OB7.
For Corsair, Go to OB7.
For Escape, Go to OB7.
For Expedition without an ATCM and with a column mounted selector lever, Go to OB3.
For Expedition without an ATCM and with a GSM, Go to OB17.
For Explorer, Go to OB7.
For F-150, Go to OB5.
For F-Series Super Duty with a 6.2L or 7.3L engine, Go to OB5.
For F-Series Super Duty with a 6.7L engine, Go to OB3.
For Navigator without an ATCM and with a GSM, Go to OB17.
For all others, Go to OB10.

OB3: VERIFY THE TCM COMMUNICATES ON THE NETWORK

Press the Read Vehicle Information button to view the results of the modules communicating on the network.
Retrieve the continuous memory DTCs.

Does the TCM pass the Network Test?

Yes	No
Go to OB4.	REFER to the Module Communications Network article to diagnose the TCM does not respond to the diagnostic scan tool.

OB4: CHECK FOR TCM DTCS

Carry out the TCM self-test.

Are any DTCs present in the TCM?

Yes	No
DIAGNOSE all TCM DTCs before diagnosing the selectable drive mode switch. REFER to the appropriate procedure in the Automatic Transmission article.	Go to OB10.

OB5: VERIFY THE PCM COMMUNICATES ON THE NETWORK

Press the Read Vehicle Information button to view the results of the modules communicating on the network.
Retrieve the continuous memory DTCs.

Does the PCM pass the Network Test?

Yes	No
Go to OB6.	REFER to the Module Communications Network article to diagnose the PCM does not respond to the diagnostic scan tool.

OB6: CHECK FOR PCM DTCS

Carry out the PCM KOEO self-test.

Are any DTCs present in the PCM?

Yes	No
DIAGNOSE all PCM DTCs before diagnosing the selectable drive mode switch. REFER to the appropriate procedure in the Electronic Engine Controls article.	Go to OB10.

OB7: CHECK THE DRIVE MODE SWITCH GROUND CIRCUIT FOR AN OPEN

Ignition OFF.
Drive Mode Switch connector disconnected. (C3685) (if equipped)
Ignition ON, engine OFF.

Measure the resistance between:

(+)	(-)
GND	Ground

Measure the resistance between:

(+) Drive Mode Switch (C3685) Connector, Harness Side	(-)
GND - GD216 (BLACK/VIOLET) - Pin 12	Ground

Is the resistance less than 3 ohms?

Yes	No
Go to OB8.	REPAIR the circuit.

OB8: CHECK THE DRIVE MODE CIRCUIT FOR AN OPEN

HVAC_B Module connector disconnected. (C228B)

Measure the resistance between:

(+)	(-) FCIM_B Connector, Harness Side
DRV_ASST	DRV_ASST

Measure the resistance between:

(+)	(-) FCIM_A Connector, Harness Side
DRV_ASST	DRV_ASST

Measure the resistance between:

OB9: CHECK THE DRIVE MODE CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between:

(+)	(-)
DRV_ASST	Ground
SDM	Ground

Measure the resistance between:

(+) Drive Mode Switch (C3685) Connector, Harness Side	(-)
SDM DWN-RT - CCD30 (BROWN/BLUE) - Pin 1	Ground
SDM UP-LT - CCD29 (BLUE) - Pin 3	Ground

Is the resistance greater than 10, 000 ohms?

Yes	No
INSTALL a new HVAC module. CHECK OASIS for any service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no services articles address this concern, INSTALL a new HVAC. REFER to the appropriate Climate Control System article.	REPAIR the circuit.

OB10: CHECK FOR VOLTAGE TO THE TOW-HAUL/OVERDRIVE SWITCH

Ignition OFF.
Ignition ON, engine OFF.

Measure the voltage between:

(+) Column Shifter Connector, Harness Side	(-)
SDM-V	Ground

Measure the voltage between:

(+) Floor Shifter Assembly Connector, Harness Side	(-)
SDM-V	Ground

Measure the voltage between:

(+) OD Connector, Harness Side	(-)
IGN START/RUN	Ground

Is the voltage above 11 volts?

Yes	No
Go to OB11.	REPAIR the circuit. VERIFY BCM fuse 18 (7.5A) is OK. If the fuse is OK, REPAIR the circuit. If the fuse is not OK, REFER to the the OEM Electrical Wiring Diagram Introduction article to determine to cause of the circuit short.

OB11: CHECK THE TOW-HAUL/OVERDRIVE CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between:

OB12: CHECK THE TOW-HAUL/OVERDRIVE CIRCUIT FOR A SHORT TO GROUND

Measure the resistance between:

(+) Column Shifter Connector, Harness Side	(-)
SDM	Ground

Measure the resistance between:

(+) Floor Shifter Assembly Connector, Harness Side	(-)
SDM	Ground

Measure the resistance between:

(+) OD Connector, Harness Side	(-)
SDM	Ground

Is the resistance greater than 10, 000 ohms?

Yes	No
CHECK OASIS for any service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new column shifter assembly, the overdrive cancel switch is part of the shifter assembly. REFER to the Automatic Transmission External Controls article.	REPAIR the circuit.

OB13: CHECK THE ABS MODULE DTCS

Put the ABS module in sleep mode by performing the following steps:
- With ALL doors closed, set the ignition from ON to OFF.
- Disconnect the diagnostic scan tool.
- Open the door, exit the vehicle and close the door.
- Wait a minimum of 90 seconds for the ABS module to enter sleep mode.
Ignition ON, engine OFF.
Carry out the ABS self-test.
Retrieve and record all ABS module DTCs.

Is DTC U0138:xx or U0439:xx present in the ABS module?

Yes	No
GO to PINPOINT TEST BM .	Go to OB14.

OB14: CHECK FOR ATCM DTCS

Ignition ON, engine OFF.
Using a diagnostic scan tool, carry out the ATCM self-test.

Are any DTCs present in the ATCM?

Yes	No
If the ATCM does not communicate with the diagnostic scan tool, REFER to the Module Communications Network article. If the ATCM communicates with the diagnostic scan tool, DIAGNOSE all ATCM DTCs before diagnosing the selectable drive mode switch. REFER to Four-Wheel Drive System article.	Go to OB15.

OB15: CHECK THE VOLTAGE TO THE ATCM

Ignition OFF.
ATCM connector disconnected. (C3639)

Measure the voltage between:

(+) Traction Control Switch Connector, Harness Side	(-)
B+	Ground

Measure the voltage between:

(+) ATCM (C3639) Connector, Harness Side	(-)
B+ - SBP31 (WHITE/RED) - Pin 1	Ground

Is the voltage greater than 11 volts?

Yes	No
Go to OB16.	VERIFY all ATCM related fuses in the BJB are OK. REFER to Fuse and Relay Information article for fusing information. If the fuses are OK, REPAIR the circuit. If the fuses are not OK, REFER to the the OEM Electrical Wiring Diagram Introduction article to locate the cause of the circuit short.

OB16: CHECK THE ATCM GROUND CIRCUIT FOR AN OPEN

Measure the resistance between:

(+) Traction Control Switch Connector, Harness Side	(-)
GND	Ground

Measure the resistance between:

(+) ATCM (C3639) Connector, Harness Side	(-)
GND - GD126 (BLACK/VIOLET) - Pin 4	Ground

Is the resistance less than 3 ohms?

Yes	No
CHECK OASIS for any service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new ATCM. REFER to the the Four-Wheel Drive Systems article	REPAIR the circuit.

OB17: CHECK THE ABS MODULE DTCS

Ignition OFF.
Ignition ON, engine OFF.
Carry out the ABS self-test.
Retrieve and record all ABS module DTCs.

Is DTC U0103:xx or U0404:xx present in the ABS module?

Yes	No
GO to PINPOINT TEST AV .	Go to OB18.

OB18: CHECK FOR GSM DTCS

Ignition ON, engine OFF.
Carry out the GSM self-test.

Are any DTCs present in the GSM?

Yes	No
If the GSM does not communicate with the diagnostic scan tool, REFER to the Module Communications Network article. If the GSM communicates with the diagnostic scan tool, DIAGNOSE all GSM DTCs before diagnosing the selectable drive mode switch. REFER to the Automatic Transmission External Controls article.	Go to OB19.

OB19: CHECK THE SDM CIRCUIT FOR A SHORT TO GROUND

Ignition OFF.
GSM connector disconnected. (C3590)
TCM connector disconnected.

Measure the resistance between:

(+) GSM (C3590) Connector, Harness Side	(-)
SDM	Ground

Is the resistance less than 3 ohms?

Yes	No
Go to OB20.	REPAIR the circuit.

OB20: CHECK THE SDM CIRCUIT FOR AN OPEN

Measure the resistance between:

(+) GSM (C3590) Connector, Harness Side	(-) TCM Connector, Harness Side
SDM	SDM

Is the resistance less than 3 ohms?

Yes	No
Go to OB21.	REPAIR the circuit.

OB21: CHECK THE SDM CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.
TCM connector connected. Make sure the connector seats and latches correctly.
Ignition ON, engine OFF.

Measure the voltage between:

(+) GSM (C3590) Connector, Harness Side	(-)
SDM	Ground

Is any voltage present?

Yes	No
REPAIR the circuit.	CHECK OASIS for any service articles: TSB, GSB, SSM or FSA. If a service article exists for this concern, DISCONTINUE this test and FOLLOW the service article instructions. If no service articles address this concern, INSTALL a new GSM. REFER to the the Automatic Transmission External Controls article.