Code
P1606
OLDSMOBILE
P — Powertrain
Serial Communication Problem With Device 6
AI status
Completed
Completed
100%
Causes
- Failed or unresponsive module (device 6)
- Open, shorted, or intermittent wiring on the serial data bus or module connectors
- Blown fuse or lost power/ground to the module
- Damaged or corroded connectors or pins
- Network interference from aftermarket electronics
- Software/configuration error or required module reprogramming
Symptoms
- Related system(s) controlled by device 6 may not operate or display errors
- Warning lights illuminated (check engine, network/communication warnings)
- Intermittent function of accessories (e.g., cluster, HVAC, radio) depending on which module is device 6
- Multiple communication-related trouble codes present
- Possible vehicle starting or drivability issues if device 6 is critical
What to check
- Use a scan tool to read stored codes and attempt communication with all modules; note which modules respond
- Identify which module is 'Device 6' from factory documentation or module ID list
- Inspect fuses and fusible links related to device 6 and the network power feed
- Visually inspect connectors, wiring and grounds for device 6 and serial data bus
- Check battery voltage and charging system baseline
- Look for signs of aftermarket accessories that might tamper with the network
Signal parameters
- Serial data network messages expected between modules; messages may be absent or corrupted
- Network message frequency and module ID responses should be visible with an appropriate scan tool or data logger
- Physical layer: check for proper supply voltage and good ground at the module; communication requires both power and ground
Diagnostic algorithm
- Verify customer concern and confirm MIL and P1606 are present. Record freeze frame and related codes.
- Using a factory-level scan tool, list present modules and attempt to communicate with the module identified as device 6.
- Consult service manual to determine which physical module corresponds to Device 6 and review its power/ground/fuse locations and wiring diagrams.
- Inspect connector at device 6 for corrosion, damage, or loose pins. Repair as needed.
- Check for proper power and ground at the module with engine off and key on. Repair any open circuits or poor grounds.
- Backprobe or monitor the serial data line while attempting communication. Compare signals to known-good values or monitor other modules' traffic.
- Wiggle test wiring harness while observing scan tool for communication changes to locate intermittent faults.
- Disconnect any aftermarket accessories that could inject noise onto the network and retest.
- If wiring and power/ground are good but the module does not communicate, attempt to reinitialize or reflash module software per factory procedure.
- If module remains unresponsive after correct power/ground and attempted reprogramming, replace the module and recheck. Clear codes and perform verification test/road test.
- Always clear codes and confirm no recurrence before returning vehicle to customer. Refer to factory service manual for module-specific programming and pairing steps.
Likely causes
- Battery voltage low or fuse for device 6 power circuit is blown
- Poor ground at module 6 or at common chassis ground
- Wiring harness damage (chafing, rodent damage, corrosion) on serial data bus
- Failed device 6 module hardware
- Module needs reprogramming or has incorrect configuration
Fault status
Status
Serial communication fault: device 6 not responding or communication corrupted on vehicle data network.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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