B1B78

Code

LAND ROVER B — Body

System pressure

Brand: LAND ROVER

Type: B — Body

Views: UK: 16 EN: 30 RU: 13

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Page language: EN

Causes

Low or high actual system pressure (pump failure, leak, restriction)
Faulty pressure sensor or transducer
Poor electrical connection, damaged wiring, or corroded connector to the sensor
Blown fuse or insufficient supply voltage to pump/sensor
Clogged filter or blocked hydraulic line
Faulty pump motor (mechanical/electrical) or valve block

Symptoms

Warning lamp or message on dash relating to the affected system
Loss or reduction of function in the associated subsystem (e.g., reduced ride height control, weak steering assist, degraded braking assist, reduced boost)
Unusual pump noise (constant running, whining, or no noise when expected)
Intermittent operation or limp-home mode for affected system
Possible diagnostic trouble codes for related subsystems

What to check

Read and record all stored codes and freeze-frame data with a capable scan tool
Check for relevant manufacturer service bulletins (TSBs) or calibration updates
Visually inspect pressure sensor, harness, and connectors for damage, corrosion, or water ingress
Check fuses and relays for pump and sensor power circuits
Inspect hoses, lines, fittings, and reservoirs for leaks or low fluid levels
Measure battery and charging voltage during test to rule out low supply voltage

Signal parameters

Pressure sensor output voltage (typical 0.5–4.5 V) or 0–5 V range depending on sensor
Engine/controller reported pressure value in kPa or bar via CAN or scan tool
Sensor reference and ground integrity (approx. 5 V reference present and near 0 V ground)
Pump current draw (amps) or duty cycle of pump control (if PWM-controlled)
Response time of pressure rise when pump is commanded (PSI/bar per second)

Diagnostic algorithm

Connect a diagnostic scanner, confirm B1B78 and capture freeze-frame and related codes.
Review system description and wiring diagrams for the specific Land Rover model to identify sensor, pump, and control module connections.
Perform a visual inspection: check sensor connector pins, harness chafing, fluid level, and obvious leaks.
With ignition on, verify sensor reference voltage and ground at the connector using a multimeter; compare to manufacturer specs.
Monitor live data: observe pressure value at rest and while commanding the pump; note if the reading is out of range, flatlines, or fluctuates.
If electrical supply and grounds are good but sensor output is implausible, disconnect sensor and measure actual system pressure directly with a calibrated pressure gauge at an accessible test port.
If actual pressure is correct but sensor reading is wrong, replace the pressure sensor/transducer and retest.
If actual pressure is low or absent, test pump operation: check pump fuse/relay, supply voltage at pump, and pump current draw. Inspect/filter and valve block for blockage.
Repair any leaks, replace faulty pump or valve block components as required, then clear codes and perform system relearn/calibration if applicable.
Road/operational test to confirm the fault does not return and that system functions are restored.

Likely causes

Failed or drifting pressure sensor / transducer
Hydraulic leak or disconnected hose causing low pressure
Pump not building pressure due to failure or electrical fault
Bad sensor connector or wire short/open
Restricted flow (clogged filter or valve) causing incorrect readings

Fault status

⚠️ Status

System pressure reading out of range or implausible signal. Inspect sensor, wiring, pump and hydraulic/air lines.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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Browse 320 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

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