Pinpoint Test J: U0100:87

WARNING: This page is about a different car, the 2021 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Wiring Diagrams Module Communications Network for schematic and connector information.

Normal Operation and Fault Conditions

In addition to communicating over HS-CAN, the GSM and PCM/ TCM communicate over a private Powertrain CAN. If the GSM does not receive expected messages from the PCM/ TCM, it will set a DTC.

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
GSM U0100:87	Lost Communication With ECM/PCM "A": Missing Message	For vehicles equipped with a gasoline engine, this DTC indicates the GSM did not receive some or all of an expected message from the PCM over the private Powertrain CAN. For vehicles equipped with a diesel engine, this DTC indicates the GSM did not receive some or all of an expected message from the TCM over the Powertrain CAN.

Possible Sources

Low system voltage
Circuit open or shorted
Incorrect PMI
Connectors damaged or pushed-out terminals, corrosion, loose wires and missing or damaged seals
PCM/ TCM fault

J1 CHECK ALL MODULES FOR LOW VOLTAGE DIAGNOSTIC TROUBLE CODES (DTCS)

Using a diagnostic scan tool, review all continuous memory diagnostic trouble codes (CMDTCs) in all modules.

Is a low voltage DTC set in any module?

Yes	RESOLVE the vehicle voltage concern. REFER to: Charging System - 2.7L EcoBoost (238kW/324PS)/3.5L EcoBoost (BM) . REFER to: Charging System - 3.3L Duratec-V6/5.0L 32V Ti-VCT . REFER to: Charging System - 3.0L Power Stroke Diesel .

GO to J2

J2 CHECK THE GSM (GEAR SHIFT MODULE) FOR DTC (DIAGNOSTIC TROUBLE CODE) U0100:87
- Using a diagnostic scan tool, retrieve all diagnostic trouble codes (DTCs) from the GSM.
Is DTC U0100:87 present?

Yes For vehicles equipped with a gasoline engine, GO to J3 For vehicles equipped with a diesel engine, GO to J10

No The concern is not present at this time.

J3 CHECK THE PCM (POWERTRAIN CONTROL MODULE) FOR DIAGNOSTIC TROUBLE CODES (DTCS)

Using a diagnostic scan tool, carry out the KOEO and KOERPCM self-tests.

Are any diagnostic trouble codes (DTCs) present in the PCM?

Yes	RESOLVE those diagnostic trouble codes (DTCs) first. REFER to the Master DTC Chart.

No	If the PCM does not respond to the diagnostic scan tool, REFER to: Controller Area Network (CAN) Module Communications Network . Otherwise, GO to J4

J4 CHECK THE GSM (GEAR SHIFT MODULE) FOR DIAGNOSTIC TROUBLE CODES (DTCS)

NOTE: If a GSM self-test is carried out, the driver door must be fully closed. A false P166B DTC may set if the driver door is not fully closed during the self-test.
- Using a diagnostic scan tool, carry out the GSM self-test.
Are any system voltage or internal module diagnostic trouble codes (DTCs) present in the GSM?

Yes RESOLVE those diagnostic trouble codes (DTCs) first. REFER to the GSMDTC Chart.

No GO to J5

J5 CHECK FOR OTHER CAUSES OF COMMUNICATION CONCERNS

NOTE: If new modules were installed prior to the DTC being set, the module configuration can be incorrectly set during the PMI or the PMI may not have been carried out.

CHECK the vehicle service history for recent service actions related to the PCM or to the GSM. If recent service history is found:
- verify correct replacement module was installed
  - HVBOM may be used to verify correct part application
- verify the configuration of replacement module was correct
  - re-configure module using as-built data if prior configuration is suspect
- verify the module was not obtained from a like vehicle and installed into customer vehicle
  - return the swapped module to source vehicle and obtain new replacement module

Were any causes of a communication concern found in the vehicle service history?

Yes	Follow the above directions to address improper module replacement or configuration. If the correct module was installed and the PMI was completed correctly, GO to J6

GO to J6

J6 ATTEMPT TO DUPLICATE THE DTC (DIAGNOSTIC TROUBLE CODE)

NOTE: If a GSM self-test is carried out, the driver door must be fully closed. A false P166B DTC may set if the driver door is not fully closed during the self-test.

Using a diagnostic scan tool, clear all diagnostic trouble codes (DTCs) from the GSM.

Road test the vehicle.

Using a diagnostic scan tool, carry out the GSM self-test.

Did DTC U0100:87 return?

Yes

GO to J7

No	The system is operating correctly at this time. The concern may have been caused by a high network traffic event or an intermittent fault condition.

J7 CHECK THE POWERTRAIN CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR AN OPEN

Ignition OFF.

Disconnect GSM C2503.

Disconnect PCM C1232T (for vehicles equipped with the 2.7L Ecoboost engine).

Disconnect PCM C1551T (for vehicles equipped with the 3.3L Duratec-V6 engine).

Disconnect PCM C175T (for vehicles equipped with the 3.5L Ecoboost engine).

Disconnect PCM C1381T (for vehicles equipped with the 5.0L 32V Ti-VCT engine).

Inspect the connectors for damaged or pushed-out terminals.

For vehicles equipped with the 2.7L Ecoboost engine, measure:

Positive Lead	Measurement / Action	Negative Lead
C2503-13	Courtesy of FORD MOTOR COMPANY	C1232T-8
C2503-14	Courtesy of FORD MOTOR COMPANY	C1232T-23

For vehicles equipped with the 3.3L Duratec-V6 engine, measure:

Positive Lead	Measurement / Action	Negative Lead
C2503-13	Courtesy of FORD MOTOR COMPANY	C1551T-8
C2503-14	Courtesy of FORD MOTOR COMPANY	C1551T-23

For vehicles equipped with the 3.5L Ecoboost engine, measure:

Positive Lead	Measurement / Action	Negative Lead
C2503-13	Courtesy of FORD MOTOR COMPANY	C175T-8
C2503-14	Courtesy of FORD MOTOR COMPANY	C175T-23

For vehicles equipped with the 5.0L 32V Ti-VCT engine, measure:

Positive Lead	Measurement / Action	Negative Lead
C2503-13	Courtesy of FORD MOTOR COMPANY	C1381T-8
C2503-14	Courtesy of FORD MOTOR COMPANY	C1381T-23

Are the resistances less than 3 ohms?

Yes

GO to J8

No	REPAIR the open circuit.

J8 CHECK THE POWERTRAIN CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR A SHORT TO GROUND

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2503-13	Courtesy of FORD MOTOR COMPANY	Ground
C2503-14	Courtesy of FORD MOTOR COMPANY	Ground

Are the resistances greater than 10, 000 ohms?

Yes

GO to J9

No	REPAIR the short to ground.

J9 CHECK FOR CORRECT PCM (POWERTRAIN CONTROL MODULE) OPERATION

NOTE: If a GSM self-test is carried out, the driver door must be fully closed. A false P166B DTC may set if the driver door is not fully closed during the self-test.

Ignition OFF.

Disconnect and inspect the GSM, PCM and all related in-line electrical 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 all disconnected electrical connectors. Make sure they seat and latch correctly.

Using the diagnostic scan tool, clear all diagnostic trouble codes (DTCs).

Road test the vehicle.

Carry out the GSM self-test.

Did DTC U0100:87 return?

Yes

CHECK for an applicable TSB, GSB, SSM, or FSA. If a service bulletin exists for this concern, discontinue this test and follow bulletin instructions. If none address this concern, Refer to PCM GUIDED ROUTINE TESTING
Internet Explorer version 11 or greater is required to perform this Pinpoint Test.
After programming the new PCM, CARRY OUT the transmission strategy download. REFER to: Transmission Strategy Download .

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

J10 CHECK THE TCM (TRANSMISSION CONTROL MODULE) FOR DIAGNOSTIC TROUBLE CODES (DTCS)

Using a diagnostic scan tool, carry out the TCM self-test.

Are any diagnostic trouble codes (DTCs) present in the TCM?

Yes	RESOLVE those diagnostic trouble codes (DTCs) first. REFER to: DTC Chart and Pinpoint Tests - 3.0L Power Stroke Diesel .

No	If the TCM does not respond to the diagnostic scan tool, REFER to: Controller Area Network (CAN) Module Communications Network . Otherwise, GO to J11

J11 CHECK THE GSM (GEAR SHIFT MODULE) FOR DIAGNOSTIC TROUBLE CODES (DTCS)

NOTE: If a GSM self-test is carried out, the driver door must be fully closed. A false P166B DTC may set if the driver door is not fully closed during the self-test.
- Using a diagnostic scan tool, carry out the GSM self-test.
Are any system voltage or internal module diagnostic trouble codes (DTCs) present in the GSM?

Yes RESOLVE those diagnostic trouble codes (DTCs) first. REFER to the GSMDTC Chart.

No GO to J12

J12 CHECK FOR OTHER CAUSES OF COMMUNICATION CONCERNS

NOTE: If new modules were installed prior to the DTC being set, the module configuration can be incorrectly set during the PMI or the PMI may not have been carried out.

CHECK the vehicle service history for recent service actions related to the TCM or to the GSM. If recent service history is found:
- verify correct replacement module was installed
  - HVBOM may be used to verify correct part application
- verify the configuration of replacement module was correct
  - re-configure module using as-built data if prior configuration is suspect
- verify the module was not obtained from a like vehicle and installed into customer vehicle
  - return the swapped module to source vehicle and obtain new replacement module

Were any causes of a communication concern found in the vehicle service history?

Yes	Follow the above directions to address improper module replacement or configuration. If the correct module was installed and the PMI was completed correctly, GO to J13

GO to J13

J13 ATTEMPT TO DUPLICATE THE DTC (DIAGNOSTIC TROUBLE CODE)

NOTE: If a GSM self-test is carried out, the driver door must be fully closed. A false P166B DTC may set if the driver door is not fully closed during the self-test.

Using a diagnostic scan tool, clear all diagnostic trouble codes (DTCs) from the GSM.

Road test the vehicle.

Using a diagnostic scan tool, carry out the GSM self-test.

Did DTC U0100:87 return?

Yes

GO to J14

No	The system is operating correctly at this time. The concern may have been caused by a high network traffic event or an intermittent fault condition.

J14 CHECK THE POWERTRAIN CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR AN OPEN

Ignition OFF.

Disconnect GSM C2503.

Disconnect TCM C1822.

Inspect the connectors for damaged or pushed-out terminals.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2503-13	Courtesy of FORD MOTOR COMPANY	C1822-46
C2503-14	Courtesy of FORD MOTOR COMPANY	C1822-45

Are the resistances less than 3 ohms?

Yes

GO to J15

No	REPAIR the open circuit.

J15 CHECK THE POWERTRAIN CAN (CONTROLLER AREA NETWORK) CIRCUITS FOR A SHORT TO GROUND

Disconnect all other modules on Powertrain CAN. REFER to Wiring Diagrams Electronic Engine Controls - 3.0L Diesel for more information.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2503-13	Courtesy of FORD MOTOR COMPANY	Ground
C2503-14	Courtesy of FORD MOTOR COMPANY	Ground

Are the resistances greater than 10, 000 ohms?

Yes

GO to J16

No	REPAIR the short to ground.

J16 CHECK FOR CORRECT TCM (TRANSMISSION CONTROL MODULE) OPERATION

NOTE: If a GSM self-test is carried out, the driver door must be fully closed. A false P166B DTC may set if the driver door is not fully closed during the self-test.

Ignition OFF.

Disconnect and inspect the GSM, TCM and all related in-line electrical 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 all disconnected electrical connectors. Make sure they seat and latch correctly.

Using the diagnostic scan tool, clear all diagnostic trouble codes (DTCs).

Road test the vehicle.

Carry out the GSM self-test.

Did DTC U0100:87 return?

Yes

CHECK for an applicable TSB, GSB, SSM, or FSA. If a service bulletin exists for this concern, discontinue this test and follow bulletin instructions. If none address this concern, INSTALL a new TCM. REFER to: Transmission Control Module (TCM) . CARRY OUT the transmission strategy download. REFER to: Transmission Strategy Download .

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