Pinpoint Test A: The PCM Does Not Respond To The Scan Tool
Communications Network
Pinpoint Tests
Pinpoint Test A: The PCM Does Not Respond To The Scan Tool
Refer to Wiring Diagram Set 14, Module Communications Network for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 25, Electronic Engine Controls - 3.5L for schematic and connector information. Diagrams By Number
Normal Operation
The PCM communicates with the scan tool through the High Speed Controller Area Network (HS-CAN). Circuits VDB04 (WH/BU) (HS-CAN +) and VDB05 (WH) (HS-CAN -) provide the network connection to the PCM. The PCM shares the HS-CAN with the Steering Effort Control Module (SECM), the ABS module, the Restraints Control Module (RCM), the 4X4 control module, the Accessory Protocol Interface Module (APIM) and the Instrument Cluster (IC). Circuit CBB47 (GN/BU) provides voltage, and circuit GD113 (BK/YE) provides ground.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- PCM
PINPOINT TEST A: THE PCM DOES NOT RESPOND TO THE SCAN TOOL
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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
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A1 CHECK THE DATA LINK CONNECTOR (DLC) PINS FOR DAMAGE
- Ignition OFF.
- Disconnect the scan tool cable from the DLC.
- Inspect DLC pins 6 and 14 for damage.
- Are DLC pins 6 and 14 OK?
Yes
GO to A2.
No
REPAIR the DLC as necessary. CLEAR the DTCs. REPEAT the network test with the scan tool.
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A2 COMPUTERS AND CONTROL SYSTEMS INFORMATION PINPOINT TEST QA VERIFICATION
- Verify that Computers and Control Systems Information pinpoint test QA has been carried out.
- Has pinpoint test QA been carried out?
Yes
GO to A3.
No
REFER to Computers and Control Systems Information, Pinpoint Tests, pinpoint test QA to diagnose no communication with the PCM.
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A3 CHECK THE HIGH SPEED CONTROLLER AREA NETWORK (HS-CAN) TERMINATION RESISTANCE
- Ignition OFF.
- NOTE: Failure to disconnect the battery will result in false resistance readings.
- Disconnect the battery ground cable.
- Disconnect the scan tool from the DLC.
- Measure the resistance between the DLC C251-6, circuit VDB04 (WH/BU), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
- Is the resistance between 54 and 66 ohms?
Yes
GO to A5.
No
GO to A4.
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A4 CHECK THE HIGH SPEED CONTROLLER AREA NETWORK (HS-CAN) CIRCUITS BETWEEN THE PCM AND THE DLC FOR AN OPEN
- Disconnect: PCM C175b.
- Measure the resistance between the PCM C175b-2, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
- Measure the resistance between the PCM C175b-3, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
- Are the resistances less than 5 ohms?
Yes
GO to A5.
No
REPAIR the circuit in question. CLEAR the DTCs. REPEAT the network test with the scan tool.
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A5 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM 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 PCM. CONNECT all the modules. 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. CONNECT all the modules. CLEAR the DTCs. REPEAT the network test with the scan tool.
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