U0134

Code

Generic U — Network/User

Lost Communication With Power Steering Control Module - Rear

Brand: Generic

Type: U — Network/User

Views: UK: 27 EN: 134 RU: 33

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Page language: EN

Causes

Faulty or disconnected rear power steering control module
Open/shorted/damaged CAN bus wiring or connectors to the PSCM
Corroded/loose connector pins, water intrusion or physical damage at module connector
Blown fuse or failed ignition/backup power supply to the module
Poor ground at the PSCM or at chassis grounds shared by the CAN network
Network interference from a shorted device or aftermarket accessory

Symptoms

Power steering assist reduced or lost (heavy steering)
Steering warning lamp / power steering warning illuminated
Other modules report network errors or show related U-codes
Intermittent steering assist or inconsistent assist levels
ABS, traction control, or stability control warnings if they share steering data
No CAN data available from the rear PSCM when viewed with a scan tool

What to check

Read all stored and pending codes and note freeze-frame data and timestamps
Verify battery voltage (engine off and cranking) and charging system health
Visually inspect PSCM connector and harness for corrosion, damage, pin push-out or water ingress
Check related fuses and relays for power to the PSCM
Use a scan tool to request data from the PSCM and check presence on the network
Check for other U-codes that indicate broader CAN bus problems

Signal parameters

CAN bus idle (recessive) voltage approximately 2.5 V on CAN High and CAN Low (nominal; confirm with vehicle specs)
Dominant state differential voltage typically ~1.5–3.0 V depending on network and transceivers
Common CAN bus speeds used by steering modules: often 500 kb/s or 250 kb/s; confirm vehicle-specific baud rate
Module supply voltage should be battery voltage (approx. 11–15 V); ignition-switched supply may be present
Module ground should measure close to 0.0 V with low resistance to chassis

Diagnostic algorithm

Confirm U0134 and any related codes with a professional scan tool; record freeze-frame data and conditions when the fault set.
Check battery/charging voltage and condition. Low voltage or excessive ripple can corrupt communications—repair as needed.
Inspect PSCM connector and harness for obvious damage, pin corrosion, bent pins, water intrusion, or unsecured connector.
Verify power and ground at the PSCM connector (with key ON). Check fuses, relays and back-probe module power/ground pins. Repair any open circuits.
Using a scan tool, attempt to communicate with the PSCM. If the module does not respond, check whether other modules on the same CAN bus are communicative.
Use an oscilloscope or capable lab scope to view CAN High/Low signals at the PSCM connector while key is ON and while cranking/starting. Look for proper recessive/dominant waveforms, noise, or short-to-B+ or short-to-ground.
If bus signals are abnormal at the PSCM but normal at another distribution point, isolate and repair the harness between those points (continuity, shorts to battery/chassis).
If wiring and power/ground check good but no communication, try swapping or bench-testing the PSCM only if manufacturer procedures allow. Consider software update or reprogramming if service bulletins apply.
After repairs, clear codes and road-test under conditions similar to freeze-frame. Re-scan to confirm the fault does not return.
If intermittent or complex network faults persist, consult manufacturer network topology, wiring diagrams, and technical service bulletins; consider professional diagnostics for bus analyzers or module replacement/programming.