P2634

Code

LAND ROVER P — Powertrain

Fuel pump B control - high circuit

Brand: LAND ROVER

Type: P — Powertrain

Views: UK: 21 EN: 29 RU: 21

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Short to battery or constant 12V on the Fuel Pump B control wire
Failed/shorted fuel pump relay or stuck contacts
Corroded/loose connector or poor pin contact at pump, relay or PCM
Damaged wiring harness (chafing, exposed conductor)
Failed fuel pump or excessive load causing driver malfunction
Faulty PCM/ECM or internal driver transistor failure

Symptoms

Malfunction Indicator Lamp (MIL) illuminated with P2634 stored
No‑start or hard start if pump is disabled or not commanded correctly
Low or no fuel pressure at the rail when Pump B should be active
Intermittent stalling or rough running under conditions when Pump B is commanded
Possible battery drain if circuit is shorted to battery

What to check

Read and record freeze frame and all stored codes; clear codes and attempt to reproduce
Visually inspect wiring, connectors, relay and fuse associated with Fuel Pump B for corrosion, heat damage or pin deformation
Inspect fuel pump B connector at tank/module and the pump relay/socket in the fuse/relay box
Backprobe the Fuel Pump B control pin at the PCM and at the pump harness with ignition ON and while commanding the pump ON (use scan tool)
Check related fuses and relays for correct operation and swapped relay test if applicable
Measure voltage and resistance on the control wire(s) to check for short to battery or short to ground

Signal parameters

Expected: control circuit inactive — near 0 V or near battery depending on architecture (confirm with service info)
Expected: when commanded ON — either the PCM will sink (low side) showing
If the control circuit measures steady battery voltage with pump OFF → indicates short to battery or stuck relay
If the control pin is stuck at high voltage when PCM is commanding OFF → suspect short to battery or relay contact stuck

Diagnostic algorithm

Connect a capable scan tool; read/record freeze frame, pending codes and live data. Verify conditions when P2634 set.
Perform a visual inspection of harnesses, connectors, relay boxes and fuses related to Fuel Pump B. Repair any damaged connectors/pins.
Backprobe the Fuel Pump B control circuit at the PCM connector and at the pump/relay harness. With ignition ON and engine OFF, observe voltage; with the PCM commanding pump ON (use scan tool or cranking), observe change. Compare to expected per service manual.
If control wire is high (battery voltage) when it should be low/off, isolate by disconnecting the pump/relay and checking voltage at the disconnected harness to see if the high is still present. If high remains with pump/relay disconnected → short to battery or PCM fault.
Check continuity from the control pin to battery positive and to ground. Look for unintended continuity to battery. Wiggle wiring to reproduce fault if intermittent.
Inspect/test the pump relay: swap with identical relay if available, or bench test relay. Replace relay if stuck/shorted.
If wiring and relay are good, bench‑test the pump by applying fused battery power (observe safety for fuel systems) to confirm pump draw and operation. Compare current draw to spec.
If the pump and harness are OK and the control wire still shows incorrect voltage at the PCM connector, suspect PCM driver failure — confirm with manufacturer diagnostics; do not replace PCM without proper bench/module testing and programming.
After repair, clear codes and test drive/recreate conditions to verify the fault does not return.

Likely causes

Short to battery on the Fuel Pump B control wire (most common)
Corroded or pushed‑out terminal at the pump/relay/engine harness causing intermittent high voltage reading
Faulty pump relay stuck closed or welded contacts applying constant battery voltage
Internal PCM fuel‑pump driver transistor shorted/high (less common)

Fault status

⚠️ Status

P2634 — Fuel Pump B Control Circuit High: high voltage detected on Fuel Pump B control circuit. MIL on; fuel pump control may be disabled or limited.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1-3 hours

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P2634 — Fuel pump B control - high circuit