Pinpoint Test G: The Restraints Control Module (RCM) Does Not Respond To The Scan Tool Or No ISO 9141 Network Communication
Communications Network
Pinpoint Tests
Pinpoint Test G: The Restraints Control Module (RCM) Does Not Respond To The Scan Tool Or No ISO 9141 Network Communication
Refer to Wiring Diagram Set 14, Module Communications Network for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 46, Supplemental Restraint System for schematic and connector information. Diagrams By Number
Normal Operation
The Restraints Control Module (RCM) communicates with the scan tool through the ISO 9141 communications network, circuit 70 (LB/WH). The RCM is the only module on the ISO 9141 network. Voltage for the RCM is provided by circuit 937 (RD/WH). Ground is provided by circuit 1203 (BK/LB).
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- RCM
PINPOINT TEST G: PINPOINT TEST G: THE RCM DOES NOT RESPOND TO THE SCAN TOOL OR NO ISO 9141 NETWORK COMMUNICATION
WARNING: Never probe the electrical connectors on air bag, Safety Canopy(R) or side air curtain modules. Failure to follow this instruction may result in the accidental deployment of these modules, which increases the risk of serious personal injury or death.
WARNING: Never probe the electrical connectors on safety belt buckle/retractor pretensioners or adaptive load limiting retractors. Failure to follow this instruction may result in the accidental deployment of the safety belt pretensioners or adaptive load limiting retractors, which increases the risk of serious personal injury or death.
NOTE: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.
NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough inspection and verification before proceeding with the pinpoint test. Inspection and Verification
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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G1 CHECK THE DATA LINK CONNECTOR (DLC) PINS FOR DAMAGE
- Ignition OFF.
- Disconnect the scan tool cable from the DLC.
- Inspect the DLC C251-7 for damage.
- Is the DLC pin 7 OK?
Yes
GO to G2.
No
REPAIR the DLC as necessary. CLEAR the DTCs. REPEAT the network test with the scan tool.
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G2 CHECK THE RCM CONNECTION
- Depower the SRS. Refer to Air Bag Systems.
- Disconnect: RCM C2041a.
- Are RCM C2041a pins 11, 12 and 16 OK?
Yes
GO to G3.
No
REPAIR the RCM connector pins as necessary. REPOWER the SRS. REFER to Air Bag Systems. CLEAR the DTCs. REPEAT the network test with the scan tool.
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G3 CHECK THE RCM VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Deactivate the SRS. Refer to Air Bag Systems.
- Repower the SRS. Refer to Air Bag Systems.
- Ignition ON.
- Measure the voltage between RCM C2041a-12, circuit 937 (RD/WH), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to G4.
No
VERIFY the Smart Junction Box (SJB) fuse 17 (10A) is OK. If OK, REPAIR the circuit. If not OK, REFER to the Wiring Diagrams to IDENTIFY the possible causes of the short circuit.
REACTIVATE the SRS. REFER to Air Bag Systems. CLEAR the DTCs. REPEAT the network test with the scan tool.
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G4 CHECK THE RCM GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between RCM C2041a-16, circuit 1203 (BK/LB), harness side and a sheet metal ground near the RCM.
- Is the resistance less than 5 ohms?
Yes
CONNECT the negative battery cable. GO to G5.
No
REPAIR the circuit. CONNECT the negative battery cable. REACTIVATE the SRS. REFER to Air Bag Systems. CLEAR the DTCs. REPEAT the network test with the scan tool.
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G5 CHECK THE ISO 9141 CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between the DLC C251-7, circuit 70 (LB/WH), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. REACTIVATE the SRS. REFER to Air Bag Systems. CLEAR the DTCs. REPEAT the network test with the scan tool.
No
GO to G6.
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G6 CHECK THE ISO 9141 CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Measure the resistance between the DLC C251-7, circuit 70 (LB/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to G7.
No
REPAIR the circuit. REACTIVATE the SRS. REFER to Air Bag Systems. CLEAR the DTCs. REPEAT the network test with the scan tool.
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G7 CHECK THE ISO CIRCUIT BETWEEN THE RCM AND THE DLC FOR AN OPEN
- Measure the resistance between the RCM C2041a-11, circuit 70 (LB/WH), harness side and the Data Link Connector (DLC) C251-7, circuit 70 (LB/WH), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to G8.
No
REPAIR the circuit in question. REACTIVATE the SRS. REFER to Air Bag Systems. CLEAR the DTCs.
REPEAT the network test with the scan tool.
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G8 CHECK FOR CORRECT RCM OPERATION
- Disconnect all the RCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the RCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new RCM. REACTIVATE the SRS. REFER to Air Bag Systems. CLEAR the DTCs. REPEAT the network test with the scan tool.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. REACTIVATE the SRS. REFER to Air Bag Systems. CLEAR the DTCs. REPEAT the network test with the scan tool.
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