Refer to
Cell 50: Class 2 Serial Data Line
for a wiring diagram.
Circuit Description
The PCM uses the serial data circuit to communicate with various other devices and systems in the vehicle. The PCM ensures that communication remains established by monitoring the serial data circuit for state of health messages from the other devices using the circuit. If the PCM detects a loss of the state of health serial data message from the EBCM/EBTCM, DTC P1602 will be set.
Conditions for Running the DTC
| • | The ignition is ON. |
| • | System voltage is greater than 8.2 volts. |
Conditions for Setting the DTC
| • | The PCM detects a loss of serial data from the EBCM/EBTCM. |
| • | The above conditions are present for longer than 5 seconds. |
Action Taken When the DTC Sets
The PCM stores conditions which were present when the DTC set as Failure Records only. This information will not be stored as Freeze Frame Records.
Conditions for Clearing the MIL/DTC
| • | The DTC becomes history when the conditions for setting the DTC are no longer present. |
| • | The history DTC clears after 40 malfunction free warm-up cycles. |
| • | The PCM receives a clear code command from the scan tool. |
Diagnostic Aids
For complete serial data line schematics, refer to
Cell 50: Class 2 Serial Data Line
.
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following conditions:
| • | Intermittent short circuit on the serial data circuit. |
Refer to
Cell 20: MIL and Data Link Connector (DLC)
and check all related wiring for an intermittent short to ground or short to voltage. |
| • | Poor connection. |
| Inspect the PCM and the affected control module harness and related connectors for improper mating, broken locks, improperly formed or damaged terminals, and poor terminal to wire connection. |
| • | Damaged harness. |
| Inspect the wiring harness for damage. Check for an intermittent short or open circuit in the wiring harnesses related to the affected control module, including the ignition, battery feed, ground, and serial data circuits. Refer to Intermittents and Poor Connections Diagnosis . |
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition that caused the DTC to be set occurs. This may assist in diagnosing the condition.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Powertrain On-Board Diagnostic System Check performed? | -- | ||
2 |
Important: If a loss of DLC data has already been diagnosed using the DLC Diagnosis table, clear this DTC and continue diagnosis with Powertrain On Board Diagnostic (OBD) System Check . Attempt to select ABS data with the scan tool. Can ABS data be displayed? | -- | ||
3 |
Was a problem found? | -- | Go to Diagnostic Aids | |
4 |
Was a problem found? | -- | ||
5 |
Was a problem found? | -- | Go to the Data Link Connector Diagnosis in ABS Brakes. | |
6 |
Does the scan tool indicate DTC P1602 failed? | -- | System OK |
