DTC P1602 Lost Communications with Brake/Traction Control (EBTCM) System Buick - VIN 1, K
Refer to Data Line in Electrical Diagnosis
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 will not illuminate the Malfunction Indicator Lamp (MIL). |
| • | The PCM will store conditions which were present when the DTC set as Fail Records data only. This information will not be stored as Freeze Frame data. |
Conditions for Clearing the MIL/DTC
| • | A history DTC will clear 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 Line in Electrical Diagnosis.
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 Serial Data Line Circuit Check in Electrical Diagnosis 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 Troubleshooting Procedures in Electrical 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 the 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? | -- | Refer to Diagnostic Aids | |
4 |
Was a problem found? | -- | ||
5 |
Was a problem found? | -- | Go to the Diagnostic System Check in ABS Brakes | |
6 |
Does the scan tool indicate DTC P1602 failed? | -- | System OK |
