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Home / DTC / C104B — Rear axle haste - Pressure regulating valve

C104B — Rear axle haste - Pressure regulating valve

Detailed page for trouble code C104B.

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Code

C104B

LAND ROVER C — Chassis

Rear axle haste - Pressure regulating valve

Brand: LAND ROVER
Type: C — Chassis
Views: UK: 5 EN: 7 RU: 4
AI status
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Page language: EN

Causes

  • Damaged or corroded electrical connector or wiring to the pressure regulating valve
  • Internal failure or seizure of the pressure regulating (solenoid) valve
  • Low or contaminated hydraulic fluid / blocked filter or port in the rear axle hydraulic circuit
  • Hydraulic leak or loss of pressure in rear axle system
  • Faulty rear axle control module (ECU) or software/calibration error
  • Intermittent ground or supply voltage faults (fused power, relays)

Symptoms

  • ABS/traction/stability warning lamp(s) illuminated
  • Rear axle locking or limited-slip function operating incorrectly (hesitation, no engagement, or stuck engagement)
  • Unusual rear-axle hydraulic noises or harsh engagement when changing drive modes
  • Communication or repeated fault codes stored for rear axle control
  • Possible limp or reduced performance modes related to stability control

What to check

  • Read and record freeze frame and all stored codes with a capable scan tool; attempt to clear and re-scan to confirm persistence
  • Visually inspect valve connector, wiring harness and axle hydraulic lines for damage, corrosion, or fluid contamination
  • Check hydraulic fluid level and condition in rear axle/hydraulic reservoir per service manual
  • Check for external hydraulic leaks around the axle and valve body
  • Using a scan tool, view live data for valve command (duty cycle/ON) and actual pressure/feedback values while commanding the valve
  • Measure supply voltage and ground at the valve connector with connector connected and key ON/engine running as specified

Signal parameters

  • Control signal: PWM/duty-cycle command from rear axle control unit (0–100% duty) — check live data while commanding
  • Command voltage: typically switched supply up to battery voltage (0–14 V) when activated — verify presence at connector
  • Ground continuity: low resistance to chassis ground when secured
  • Coil resistance/current draw: measure valve coil resistance and compare to manufacturer spec (refer to service manual rather than guessing values)
  • Feedback/pressure signal: monitor axle pressure sensor output (voltage or CAN/live data) while commanding valve

Diagnostic algorithm

  1. Connect a capable scan tool and record all codes and live data. Note whether C104B is current or historic and any associated codes.
  2. Inspect valve connector and wiring for corrosion, pin damage, broken wires or poor mating; repair any damage and re-test.
  3. Check fuses/relays and supply voltage to the valve circuit; verify proper ground at valve connector.
  4. With the scan tool, command the pressure regulating valve ON/OFF or vary duty cycle while observing valve command parameter and rear-axle pressure/feedback. Confirm command is issued and whether pressure responds.
  5. Measure valve coil resistance with connector disconnected and compare to manufacturer spec. If open/short or out of range, suspect valve electrical failure.
  6. Inspect hydraulic fluid level/condition and filter/ports for blockage. If contaminated, flush and replace fluid and filters per procedure.
  7. Check for hydraulic leaks or restricted passages that prevent pressure change even if valve operates electrically.
  8. If valve electrically operates but pressure does not respond, consider replacement of valve/poppet or service of hydraulic assembly.
  9. After repair, clear codes, perform any required relearn/calibration procedures, and road-test to confirm no recurrence.
  10. If all wiring and valve check OK, evaluate rear axle/vehicle control module for internal fault or update software per TSB/service information.

Likely causes

  • Failed or sticking pressure regulating valve (solenoid)
  • Corroded/broken valve connector or pin(s) causing open/short
  • Hydraulic contamination or blocked passage affecting valve movement
  • Poor supply/ground to valve due to blown fuse/relay or broken wire

Fault status

⚠️ Status
Rear axle pressure regulating valve circuit fault detected — electrical or hydraulic response out of specification. Module logged C104B: check wiring, valve operation, hydraulic pressure and module functions.
🔴 Repair difficulty: Hard
⏱️ Diagnostic time: 1.5-3 hours

Similar codes

C1040 C1041 C1042 C105B C106B
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