Refer to
Serial Data Class 2
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 more 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 will not illuminate the Malfunction Indicator Lamp (MIL). |
| • | The PCM stores the conditions that were present when the DTC set as Fail Records data only. This information is not stored as Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | A history DTC clears after 40 consecutive warm-up cycles have occurred without a malfunction. |
| • | DTC can be cleared by using the scan tool Clear Info function or by disconnecting the PCM battery feed. |
Diagnostic Aids
For complete serial data line schematics, refer to
Serial Data Class 2
.
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:
| • | An intermittent short circuit on the serial data circuit--Refer
to
Serial Data Class 2
and check all related wiring for an intermittent short to ground or short to voltage. |
| • | A faulty connection--nspect 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. Use a corresponding mating terminal to test for proper terminal tension. |
| • | A 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 Wiring Repairs in Wiring Systems . |
Reviewing the Fail Records vehicle mileage since the diagnostic test last failed may help determine how often the condition occurs that caused the DTC to set. This may assist in diagnosing the condition.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | ||
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? | -- | Go to Diagnostic Aids |
