Pinpoint Test A: B129C:08

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.

NOTE: Before disconnecting any of the active park assist sensors, verify the connectors are properly seated and latched.

Refer to PARKING AID for schematic and connector information.

Normal Operation and Fault Conditions

REFER to: Parking Aid - System Operation and Component Description .

DTC Fault Trigger Conditions

DTC	Description	Fault Trigger Condition
IPMA B129C:08	Left Front Side Sensor: Bus Signal/Message Failures	A continuous and on-demand DTC that sets in the IPMA when there is a message failure on the LIN for the left front active park assist sensor.

Possible Sources

Wiring, terminals or connectors
Left front active park assist sensor
IPMA

A1 CHECK THE DIAGNOSTIC TROUBLE CODES (DTCS) FROM THE IPMA (IMAGE PROCESSING MODULE A) SELF-TEST

Ignition ON.

Using a diagnostic scan tool, perform the IPMA self-test.

Check the IPMA Diagnostic Trouble Codes (DTCs) from the self-test.

Are Diagnostic Trouble Codes (DTCs) for multiple front parking aid sensors recorded?

Yes

GO to A2

No	* For DTC B129C:08 GO to A3 * For all other IPMA Diagnostic Trouble Codes (DTCs), REFER to the IPMA DTC Chart in Diagnostic Trouble Code (DTC) Chart .

A2 CHECK THE FRONT BUMPER WIRING HARNESS
- Inspect the front bumper wiring harness for opens, shorts, grounds or corrosion.
Is the front bumper wiring harness OK?

Yes GO to A3

No REPAIR or INSTALL a new front bumper wiring harness.

A3 CHECK FOR VOLTAGE TO THE SENSOR

Ignition OFF.

Disconnect left front active park assist sensor C1854.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1854-1	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 9 volts?

Yes

GO to A4

No	REPAIR the circuit.

A4 CHECK FOR GROUND AT THE SENSOR

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1854-1	Courtesy of FORD MOTOR COMPANY	C1854-3

Is the voltage greater than 9 volts?

Yes

GO to A5

No	REPAIR the circuit.

A5 CHECK THE SENSOR FOR A SHORT TO GROUND

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1854-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to A6

No	REPAIR the circuit.

A6 CHECK THE SENSOR FOR A SHORT TO POWER

Disconnect IPMA C242A.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1854-2	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the affected circuits.

GO to A7

A7 CHECK THE SENSOR FOR A SHORT TO VREF OR SIGNAL RETURN CIRCUITS

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1854-2	Courtesy of FORD MOTOR COMPANY	C1854-1
C1854-2	Courtesy of FORD MOTOR COMPANY	C1854-3

Are the resistances greater than 10, 000 ohms?

Yes

GO to A8

No	REPAIR the affected circuits.

A8 CHECK THE SENSOR CIRCUITS FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1854-1	Courtesy of FORD MOTOR COMPANY	C242A-22
C1854-2	Courtesy of FORD MOTOR COMPANY	C242A-7
C1854-3	Courtesy of FORD MOTOR COMPANY	C242A-11

Are the resistances less than 3 ohms?

Yes

GO to A9

No	REPAIR the affected circuit.

A9 INSTALL A KNOWN GOOD SENSOR
- Connect IPMA C242A.
- Install a known good sensor for the suspect left front active park assist sensor. REFER to: Front Active Park Assist Sensors .
- Ignition ON.
- Using a diagnostic scan tool, clear the IPMADTC and repeat the self-test.
Is DTC B129C:08 still present?

Yes GO to A10

No INSTALL a new left front active park assist sensor. REFER to: Front Active Park Assist Sensors .

A10 CHECK FOR CORRECT IPMA (IMAGE PROCESSING MODULE A) OPERATION

Ignition OFF.

Disconnect and inspect all IPMA 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 IPMA 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 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 IPMA. REFER to: Image Processing Module A (IPMA) .

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.