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 23, Electronic Engine Controls - 2.3L for schematic and connector information. Diagrams By Number
Refer to Wiring Diagram Set 25, Electronic Engine Controls - 4.0L 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).
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
NOTE: Failure to disconnect the battery when instructed will result in false resistance readings. Refer to Battery.
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A1 CHECK THE DLC PINS FOR DAMAGE
- Ignition OFF.
- Disconnect the scan tool cable from the Data Link Connector (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 VERIFY WHETHER OTHER HS-CAN MODULES PASS THE NETWORK TEST
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Network Test.
- In the LH pane of the Integrated Diagnostic System (IDS) network test display screen, verify whether any HS-CAN modules passed the network test.
- Is the text "pass" or a DTC listed next to any of the following modules (if equipped): 4X4 control module, ABS module, Instrument Cluster (IC), Occupant Classification System Module (OCSM), Restraints Control Module (RCM), Smart Junction Box (SJB) or PCM?
Yes
If "pass" or a DTC was listed next to the PCM, a network fault is not currently present. GO to Pinpoint Test H to diagnose an intermittent HS-CAN fault condition. Pinpoint Test H: Intermittent No High Speed Controller Area Network (HS-CAN) Communication, One Or More Modules Are Not Respond
If "pass" or a DTC was listed next to one or more modules other than the PCM, GO to A3.
No
No modules are currently communicating on the HS-CAN. GO to Pinpoint Test I to diagnose no HS-CAN communication. Pinpoint Test I: No High Speed Controller Area Network (HS-CAN) Communication, All Modules Are Not Responding
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A3 CHECK THE PCM VOLTAGE SUPPLY CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: PCM C175b.
- Ignition ON.
- Measure the voltage between the PCM, harness side and ground as follows:
- Are the voltages greater than 10 volts?
Yes
GO to A4.
No
VERIFY the Battery Junction Box (BJB) fuses 21 (10A) and 39 (15A) are OK.
If OK, REPAIR the circuit in question.
If not OK, REFER to the Wiring Diagrams to identify the possible causes of the circuit short. CLEAR the DTCs. REPEAT the network test with the scan tool. Diagrams By Number
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A4 CHECK THE PCM GROUND CIRCUITS FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the PCM, harness side and ground as follows:
- Are the resistances less than 5 ohms?
Yes
GO to A5.
No
REPAIR the circuit. CONNECT the negative battery cable. CLEAR the DTCs. REPEAT the network test with the scan tool.
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A5 CHECK THE HS-CAN TERMINATION RESISTANCE
- 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
CONNECT the negative battery cable. GO to A7.
No
GO to A6.
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A6 CHECK THE HS-CAN CIRCUITS BETWEEN THE PCM AND THE DLC FOR AN OPEN
- Measure the resistance between the PCM C175b-11, circuit VDB04 (WH/BU), harness side and the DLC C251-6, circuit VDB04 (WH/BU), harness side.
- Measure the resistance between the PCM C175b-23, circuit VDB05 (WH), harness side and the DLC C251-14, circuit VDB05 (WH), harness side.
- Are the resistances less than 5 ohms?
Yes
CONNECT the negative battery cable. GO to A7.
No
REPAIR the circuit in question. CONNECT the negative battery cable.
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A7 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. REFER to Computers and Control 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.
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