B10DF

Code

LAND ROVER B — Body

Main Cylinder Isolation Valve

Brand: LAND ROVER

Type: B — Body

Views: UK: 15 EN: 25 RU: 18

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Page language: EN

Causes

Open or shorted valve coil (electrical failure)
Poor connector or wiring (corrosion, broken wire, damaged terminal)
Loss of power or ground to the valve (fuse, relay, module output)
Valve mechanically stuck or contaminated (internal debris, corrosion)
Faulty ABS/hydraulic control module or driver circuit
Hydraulic pressure issues or internal master cylinder leakage affecting valve operation

Symptoms

ABS and/or brake warning lamp illuminated
Reduced ABS function or loss of traction control intervention
Longer or inconsistent pedal travel under ABS activation
Brake feel changed during modulation events (pulsation or stiffness)
Possible stored communication or hydraulic related DTCs

What to check

Retrieve all stored codes and freeze frame data with a compatible scan tool
Check for related ABS, traction control, and network communication codes (U-codes)
Visually inspect the isolation valve connector and wiring for corrosion, damage, or loose pins
Check fuses and relays supplying the valve/ABS module
Command/actuate the valve with a diagnostic tool and observe response
Measure resistance of the valve coil and compare to manufacturer spec

Signal parameters

Typical valve type: solenoid (on/off or PWM-driven by ABS module)
Resting coil resistance: expect a low-ohm value (consult model-specific spec — commonly 5–30 Ω)
Command signal: switched battery voltage or PWM from ABS module (0–12 V range)
Duty cycle when modulated: varies with braking algorithm — check live data
Current draw when activated: moderate (may be several hundred mA); excessive or zero current indicates fault
Response time: valve should actuate immediately when commanded; measurable delay indicates mechanical/electrical issue

Diagnostic algorithm

Connect a capable diagnostic scanner and read all ABS and body module codes; record freeze frame/live data.
Inspect the valve and wiring: disconnect connector, check for corrosion, bent pins, water ingress, or damaged insulation.
Check fuses/relays related to ABS/hydraulic modules; replace if blown and retest.
With ignition on (engine off) backprobe the valve connector: verify battery feed and ground presence while commanding the valve on and off with the scan tool.
Measure coil resistance at the valve connector (unplugged). Compare to factory spec. If open or shorted, replace the valve.
Command the valve with the diagnostic tool while monitoring voltage and current. No voltage/command indicates module/driver or communication fault; voltage present but no coil current indicates internal valve fault.
If electrical checks are good but valve does not actuate, consider hydraulic blockage or internal sticking — inspect brake fluid, master cylinder and hydraulic lines; perform controlled functional tests per service manual.
If wiring and valve check good, investigate the ABS/hydraulic module driver circuit: check for related U-codes (communication faults) and perform module testing or replacement as per manufacturer guidance.
After repair, clear codes, perform actuator tests and road test with ABS activation scenarios to confirm proper operation and that no new codes reappear.

Likely causes

Corroded connector at the isolation valve
Valve solenoid coil out of specified resistance range
Blown fuse or faulty relay feeding the valve
Contaminated brake fluid or internal hydraulic contamination preventing valve movement
Faulty ABS/hydraulic control module output stage

Fault status

⚠️ Status

Main Cylinder Isolation Valve fault detected. Module commanded valve but response/feedback out of expected range or electrical fault present.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0 - 2.5 hours

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