Totally Integrated Power Module (TIPM)
U0010-CAN INTERIOR BUS
For a complete wiring diagram, refer to the Wiring Information.
Theory of Operation
The primary communication network between electronic control modules on this vehicle is the Controller Area Network (CAN) data bus system. The Controller Area Network (CAN) data bus allows all electronic modules connected to the bus to share information with each other. Regardless of whether a message originates from a module on the higher speed CAN C (500K) Bus or on the lower speed CAN Interior High Speed (IHS) (125K) Bus the message structure and layout is similar, which allows the Totally Integrated Power Module/Central GateWay (TIPM or TIPMCGW) to process and transfer messages between the CAN buses. The TIPM also stores Diagnostic Trouble Codes (DTCs) for certain bus network faults.
All modules transmit and receive messages over one of these buses. Data exchange between the modules is achieved by serial transmission of encoded data messages (a form of transmission in which data bits are sent sequentially, one at a time, over a single line). Each module can both send and receive serial data simultaneously. Each data bit of a CAN Bus message is carried over the bus as a voltage differential between the two bus circuits which, when strung together, form a message. Each module uses arbitration to sort the message priority if two competing messages are attempting to be broadcast at the same time. Corruption of a single bit within a message will corrupt the entire message. Each message contains a Cyclic Redundancy Check (CRC) which specifies the message size exactly. If the message detected conflicts with the CRC the ECU receiving it will determine the message to be an error and consider that communication has not been possible. Diagnosis of this condition using a lab scope may reveal activity that appears to be Bus data messages even if no actual communication is possible. Communication problems that affect the whole bus, as a result of opens and terminal push outs are more likely to occur on data busses that operate at a high speed than a data bus that operates at a lower speed.
When an open circuit or terminal push out occurs one or more modules can become isolated from the remainder of the bus. The isolated module will attempt to communicate, but will not be able to receive messages or determine arbitration from other modules. Each time the isolated module attempts to communicate it alters the bus voltage on the intact bus circuit. Without functioning arbitration the isolated module alters the bus voltage while other bus messages are being sent thereby corrupting the messages on the remainder of the bus.
The CAN bus modules are connected in parallel to the two-wire bus using a twisted pair, where the wires are wrapped around each other to provide shielding from unwanted electromagnetic induction, thus preventing interference with the relatively low voltage signals being carried through them. While the CAN bus is operating (active), one of the bus wires will carry a higher voltage and is referred to as the CAN High or CAN bus (+) wire, while the other bus wire will carry a lower voltage and is referred to as the CAN Low or CAN bus (-) wire.
- When Monitored:
With the ignition on.
- Set Condition:
The Totally Integrated Power Module (TIPM) detects a short to ground on the CAN Interior Bus (125K) (+) circuit or a short to voltage on the CAN Interior Bus (125K) (-) circuit.
1. TEST FOR INTERMITTENT CONDITION
1. Turn the ignition on.
2. With the scan tool, record and erase TIPM DTCs.
3. Cycle the ignition from on to off three times.
4. Turn the ignition on.
5. With the scan tool, read active TIPM DTCs.
Does the scan tool display this DTC as active?
Yes
- Go To 2
No
- Test complete, the condition or conditions that originally set this DTC are not present at this time. Using the wiring diagrams as a guide, check all related splices and connectors for signs of water intrusion, corrosion, pushed out or bent terminals, and correct pin tension.
2. ANY CAN INTERIOR BUS (125K) MODULE - INTERNAL SHORT
NOTE: When performing this step, turn the ignition off (wait one minute) before disconnecting any module. When the module is disconnected turn the ignition on.
NOTE: This step is to determine if the fault is internal within a module.
1. While monitoring the scan tool, disconnect each CAN Interior Bus (125K) module (except for the TIPM), one at a time.
2. Check for this DTC to become active after disconnecting each CAN Interior Bus (125K) module the vehicle is equipped with.
NOTE: If the DTC becomes stored when a particular module is disconnected, that module is causing the DTC to set.
With all the CAN Interior Bus modules disconnected, does the scan tool display this DTC as active?
Yes
- Go To 3
No
- Replace the module that when disconnected caused this DTC to become stored.
- Perform the BODY VERIFICATION TEST. Body Verification Test.
3. (D265) CAN INTERIOR BUS (125K) (+) CIRCUIT SHORTED TO GROUND
1. Turn the ignition off.
2. Measure the resistance between ground and the (D265) CAN Interior Bus (125K) (+) circuit at the TIPM C7 harness connector.
Is any resistance present?
Yes
- Repair the short to ground in the (D265) CAN Interior Bus (125K) (+) circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.
No
- Go To 4
4. (D264) CAN INTERIOR BUS (125K) (-) CIRCUIT SHORTED TO VOLTAGE
1. Turn the ignition on.
2. Measure the voltage at the (D264) CAN Interior Bus (125K) (-) circuit at the TIPM C7 harness connector.
Is the voltage above 6 volts?
Yes
- Repair the short to voltage in the (D264) CAN Interior Bus (125K) (-) circuit.
- Perform the BODY VERIFICATION TEST. Body Verification Test.
No
- Inspect the wiring and connectors for damage or short circuits. If OK, replace the TIPM. Totally Integrated Power Module (TIPM) - Removal.
- Perform the BODY VERIFICATION TEST. Body Verification Test.