U1703

Code

Generic U — Network/User

Invalid Data Received From Powertrain Control Module

Brand: Generic

Type: U — Network/User

Views: UK: 18 EN: 17 RU: 14

AI status

Completed

ready

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Page language: EN

Causes

Faulty or intermittent CAN/LIN bus communication between PCM and other modules
Damaged wiring or poor connector contact at PCM or receiving module
Low or unstable vehicle battery voltage or poor ground connections
Faulty PCM (hardware or internal memory corruption)
Software mismatch, corrupted calibrations, or incomplete module programming/update
Bus termination resistor open or incorrect resistance

Symptoms

Illuminated MIL or other warning lamps
Intermittent or permanent loss of engine or drivability-related functions reported by other modules
Communication-related DTCs stored (U0xxx family or U1xxx family) in multiple modules
Vehicle may enter limp mode or show degraded performance
Inconsistent or missing data on scan tool parameters from PCM

What to check

Read all stored and pending DTCs and capture freeze-frame and live data with a capable scan tool
Check battery voltage and charging system (should be stable and typically >12.2 V at rest with ignition on)
Inspect PCM and receiving-module connectors for corrosion, bent pins, or poor seating
Visually inspect CAN/LIN wiring harness for damage, pinched areas, or repairs
Check main chassis and engine grounds for tightness and corrosion
Measure CAN termination and bus resistance (typical ~60 ohms across CANH-CANL with key on)

Signal parameters

CAN bus idle voltages: CANH ≈ 2.5–3.5 V, CANL ≈ 1.5–2.5 V (values vary by vehicle)
Differential CAN voltage during dominant bit ≈ 1.0–2.0 V
Termination resistance across CANH-CANL ≈ 60 ohms (two 120-ohm resistors in parallel)
Expected data rates: commonly 250 kbps or 500 kbps (verify vehicle-specific bus speed)
LIN bus idle ≈ battery voltage; communication pulses referenced to ground (if applicable)

Diagnostic algorithm

Scan: Record all codes and freeze-frame data from all modules. Note related U-codes and P-codes.
Reproduce: With a known-good battery or fully charged battery, attempt to reproduce while monitoring live data.
Power/Ground: Verify battery voltage, starter/charging health, and clean/tighten engine and chassis grounds.
Visual: Inspect PCM and affected module connectors and wiring. Repair or reseat any suspect connectors.
Clear and Monitor: Clear codes and perform functional test drive while monitoring PCM messages and live parameters.
Bus Resistance: Measure CANH–CANL resistance (key ON) — expect ~60 ohms. If out of range, isolate sections to find open/short.
Continuity/Shorts: With power removed, check wiring for continuity to expected modules and for shorts to battery/ground.
Oscilloscope: If intermittent or complex, record CAN waveforms at the receiving module and at the PCM to compare timing, voltage levels, and noise.
Isolate Modules: Disconnect non-essential modules one at a time (where safe) to determine if a particular module is causing bus corruption.
Software: Verify module calibration and software levels. Reflash or update PCM and affected module if manufacturer procedure recommends.
Module Replacement: Only after wiring, power, grounds, and software are confirmed good and fault follows module, consider replacing the faulty module and program as required.
Safety note: Avoid live-backprobing power circuits with high current connected unless following vehicle-specific procedures; disconnect battery when performing connector repairs.

Likely causes

Open, shorted, or high-resistance CAN/LIN wiring between PCM and receiving module
Poor battery or ground connection causing corrupted transmissions
Connector corrosion, bent pins, or loose terminal at PCM or receiving module
PCM with failed transceiver or corrupted firmware
Improper module reflash or incomplete software update