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Home / DTC / P0C23 — Electric Automatic Transmission Fluid Pump Control Module Open circuit

P0C23 — Electric Automatic Transmission Fluid Pump Control Module Open circuit

Detailed page for trouble code P0C23.

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22,461specific
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Code

P0C23

LAND ROVER P — Powertrain

Electric Automatic Transmission Fluid Pump Control Module Open circuit

Brand: LAND ROVER
Type: P — Powertrain
Views: UK: 6 EN: 6 RU: 7
AI status
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Page language: EN

Causes

  • Open or broken wiring in pump control circuit
  • Corroded, loose or damaged connector(s) at pump control module or PCM/TCM
  • Blown fuse or failed relay supplying pump module
  • Failed pump control module or pump motor
  • Poor or missing ground at pump or module
  • Water ingress or physical damage to harness/connector

Symptoms

  • Transmission will not develop line pressure or will enter limp mode
  • No pump motor noise when ignition is on or during cranking
  • Transmission warning light or MIL (TCM/ECM warning) illuminated
  • Reduced or no drive/engagement in gear selection
  • Extended cranking or inability to engage park/drive
  • Fault stored in TCM/ECM and inability to command pump

What to check

  • Check battery voltage (engine off and cranking) — must be within normal range
  • Check for presence of the P0C23 code and any related transmission or communication codes with a scan tool
  • Inspect fuses/relays for pump supply and replace if blown
  • Visually inspect connectors at pump control module and transmission for corrosion, bent pins, or water intrusion
  • Wiggle test harness while monitoring live data to see if code or signal changes
  • Measure continuity and resistance of wiring between pump control module and TCM/ECM and between module and ground

Signal parameters

  • Battery/supply voltage to pump module: ~11–14 V with ignition on
  • Control output: PWM or switched 0–12 V when commanded by TCM/ECM (should change when commanded)
  • Ground continuity:
  • Open-circuit indication: infinite/OL resistance between expected supply or control pin and module/TCM
  • Scan tool: pump status should switch from OFF to ON when commanded; if open, status will not change

Diagnostic algorithm

  1. Retrieve freeze frame and all stored codes with a diagnostic scanner; note any communication/TCM codes. 2) Verify battery voltage is adequate (11–14 V) and check/replace any fuses or relays supplying the pump control module. 3) With ignition off, visually inspect and disconnect the pump module connector(s); check pins for corrosion, bent or pushed-out terminals and repair as needed. 4) Check ground at module: remove bolt and measure resistance to chassis; repair any resistance >1 ohm. 5) Backprobe supply and control pins at the pump control module connector. With ignition ON, confirm battery voltage at supply pin; with a technician command, confirm control signal (voltage/PWM). 6) If supply is present but control signal is open/inactive, trace continuity from TCM/ECM output pin to pump module; repair any open circuits. 7) If open persists at the module end and wiring is good, remove/bench-test or substitute pump control module (if serviceable) to confirm module failure. 8) If module and wiring are good but pump motor does not run when commanded, check pump motor resistance and supply directly (bench test) — replace pump if motor is open. 9) After repairs, clear codes, perform relearn or adaptation procedures if required, then road test and re-scan to confirm fault does not return.

Likely causes

  • Connector corroded at pump control module or transmission fluid pump
  • Damaged harness section between TCM/ECM and pump control module (pin break)
  • Blown fuse protecting pump control circuit
  • Failed pump control module (open output)
  • Poor ground at transmission case or module mounting point

Fault status

⚠️ Status
Open circuit detected in Electric Automatic Transmission Fluid Pump Control Module circuit — pump control is not receiving expected electrical connection.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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