Body Control Module B (BCM-B)

Special Tool(s)

	Fluke 77-IV Digital Multimeter FLU77-4 or equivalent
	Vehicle Communication Module (VCM) and Integrated Diagnostic System (IDS) software with appropriate hardware, or equivalent scan tool
	Flex Probe Kit 300-NUD105-R025DE or equivalent

Principles of Operation

The Body Control Module B (BCM-B) controls various systems by monitoring inputs from switches, sensors and messages sent from other modules on the Medium Speed Controller Area Network (MS-CAN). Based on the inputs received, the BCM-B activates outputs. For example, the BCM-B monitors the stoplamp switch and messages received from the Smart Junction Box (SJB) regarding ignition state and door ajar status. Based on this input, the BCM-B may provide voltage to the stoplamps or activate the ambient lighting.

Field-Effect Transistor (FET) Protection

A Field-Effect Transistor (FET) is a type of transistor that when used with module software can be used to monitor and control current flow on module outputs. The FET protection strategy is used to prevent module damage in the event of excessive current flow.

The BCM-B utilizes an FET protective circuit strategy for many of its outputs (for example, a stoplamp output circuit). Output loads (current level) are monitored for excessive current (typically short circuits) and are shut down (turns off the voltage or ground provided by the module) when a fault event is detected. A short circuit DTC is stored at the fault event and a cumulative counter is started.

When the demand for the output is no longer present, the module resets the FET circuit protection to allow the circuit to function. The next time the driver requests a circuit to activate that has been shut down by a previous short ( FET protection) and the circuit is still shorted, the FET protection shuts off the circuit again and the cumulative counter advances.

When the excessive circuit load occurs often enough, the module shuts down the output until a repair procedure is carried out. Each FET protected circuit has 3 predefined levels of short circuit tolerance based on the harmful effect of each circuit fault on the FET and the ability of the FET to withstand it. A module lifetime level of fault events is established based upon the durability of the FET . If the total tolerance level is determined to be 600 fault events, the 3 predefined levels would be 200, 400 and 600 fault events.

When each tolerance level is reached, the short circuit DTC that was stored on the first failure cannot be cleared by a command to clear the continuous DTCs. The module does not allow this code to be cleared or the circuit restored to normal operation until a successful self-test proves that the fault has been repaired. After the self-test has successfully completed (no on-demand DTCs present), DTC U1000:00 and the associated DTC (the DTC related to the shorted circuit) automatically clears and the circuit function returns.

When each level is reached, the DTC associated with the short circuit sets along with DTC U1000:00. These DTCs can be cleared using the module on-demand self-test, then the Clear DTC operation on the scan tool (if the on-demand test shows the fault corrected). The module never resets the fault event counter to zero and continues to advance the fault event counter as short circuit fault events occur.

If the number of short circuit fault events reach the third level, then DTCs U1000:00 and U3000:49 set along with the associated short circuit DTC. DTC U3000:49 cannot be cleared and the module must be replaced after the repair.

Inspection and Verification

1. Verify the customer concern.

2. Visually inspect for obvious signs of electrical damage.

  Visual Inspection Chart

3. If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.

4. NOTE: Make sure to use the latest scan tool software release.

   If the cause is not visually evident, connect the scan tool to the Data Link Connector (DLC).

5. NOTE: The Vehicle Communication Module (VCM) LED prove-out confirms power and ground from the DLC are provided to the VCM .

   If the scan tool does not communicate with the VCM :
   • Check the VCM connection to the vehicle.
   • Check the scan tool connection to the VCM .
   • Refer to Section 418-00 , No Power To The Scan Tool, to diagnose no power to the scan tool.

6. If the scan tool does not communicate with the vehicle:
   • Verify the ignition key is in the ON state.
   • Verify the scan tool operation with a known good vehicle.
   • Refer to Section 418-00 to diagnose no response from the PCM.

7. Carry out the network test.
   • If the scan tool responds with no communication for one or more modules, refer to Section 418-00 .
   • If the network test passes, retrieve and record the continuous memory DTCs.

8. Clear the continuous DTCs and carry out the self-test diagnostics for the BCM-B .

9. If the DTCs retrieved are related to the concern, go to the Body Control Module B (BCM-B) DTC Chart.

10. If no DTCs related to the concern are retrieved, GO to Symptom Chart .

DTC Charts

 Body Control Module B (BCM-B) DTC Chart

NOTE: This module utilizes a 5-character DTC followed by a 2-character failure-type code. The failure-type code provides information about specific fault conditions such as opens, or shorts to ground. Continuous memory DTCs have an additional 2-character DTC status code suffix to assist in determining DTC history.

Symptom Chart

Pinpoint Tests

Pinpoint Test E: DTC P2533:14

Refer to Wiring Diagrams Cell 11 , Fuse and Relay Information for schematic and connector information.

Refer to Wiring Diagrams Cell 89 , Interior Lamps for schematic and connector information.

Normal Operation
• DTC P2533:14 (Ignition Switch Run/Start Position Circuit: Circuit Short To Ground Or Open) — an on-demand DTC that sets when the BCM-B detects no voltage from the run/start circuit.

This pinpoint test is intended to diagnose the following:

• Fuse
• Wiring, terminals or connectors
• BCM-B
• SJB

PINPOINT TEST E: DTC P2533:14

Pinpoint Test F: DTC U0140:87

Normal Operation
• DTC U0140:87 (Lost Communication With Body Control Module: Missing Message) — a continuous memory DTC set by the BCM-B if data messages received from the SJB over the the Medium Speed Controller Area Network (MS-CAN) are missing for 5 seconds or longer.

This pinpoint test is intended to diagnose the following:

• Communication network concern
• BCM-B
• SJB

PINPOINT TEST F: DTC U0140:87

Pinpoint Test G: DTC U0155:87

Normal Operation
• DTC U0155:87 (Lost Communication With Instrument Panel Cluster (IPC) Control Module: Missing Message) — a continuous memory DTC set by the BCM-B if data messages received from the IPC over the Medium Speed Controller Area Network (MS-CAN) are missing for longer than 5 seconds.

This pinpoint test is intended to diagnose the following:

• Communication network concern
• BCM-B
• IPC

PINPOINT TEST G: DTC U0155:87

Pinpoint Test H: DTC U1000: 00

Normal Operation

The Body Control Module B (BCM-B) controls the output of several vehicle systems by means of solid state drivers. When an overload occurs on any of these drivers, a DTC sets. The module also tracks the number of repetitive faults on each of these circuits. The module compares this number of overloads to 3 progressive thresholds established for each circuit.

At the each threshold, DTC U1000:00 sets along with the DTC associated with the affected circuit.

• DTC U1000:00 (Solid State Driver Protection Activated - Driver Disabled: No Sub Type Information) — a continuous DTC that sets when the BCM-B has disabled an output circuit due to a repetitive fault that overloads said circuit. A corresponding DTC for the circuit in question is also set.

When DTC U3000:49 is set because the module has reached a third threshold and the BCM-B has permanently disabled an output, a measurement using a digital multimeter of the affected output circuit is required to make sure the fault condition no longer exists.

This pinpoint test is intended to diagnose the following:

• Output circuit short
• BCM-B

PINPOINT TEST H: DTC U1000: 00

Pinpoint Test I: DTC U3003:62

Refer to Wiring Diagrams Cell 89 , Interior Lamps for schematic and connector information.

Normal Operation
• DTC U3003:62 (Battery Voltage: Signal Compare Failure) — a continuous and on-demand DTC that sets when the BCM-B detects battery voltage 1.5 volts above or below specific thresholds.

This pinpoint test is intended to diagnose the following:

• Wiring, terminals or connectors
• High circuit resistance
• Charging system concern
• BCM-B

PINPOINT TEST I: DTC U3003:62

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

NOTE: Failure to disconnect the battery when instructed results in false resistance readings. Refer to Section 414-01 .

NOTE: DTC U3003:62 may be stored in the module memory due to previous battery charging or vehicle jump starting events.