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Home / DTC / C1748 — Key entry - short circuit to ground

C1748 — Key entry - short circuit to ground

Detailed page for trouble code C1748.

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Code

C1748

LAND ROVER C — Chassis

Key entry - short circuit to ground

Brand: LAND ROVER
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged wiring harness with exposed conductor contacting chassis ground
  • Corroded or contaminated connector at BCM or door module
  • Failed keyless entry switch, door lock actuator, or microswitch internally shorted to ground
  • Water ingress in door or module causing a short
  • Aftermarket alarm or remote start improperly wired
  • Faulty BCM or door control module internal short

Symptoms

  • Keyless/key entry operation inoperative or intermittent (no lock/unlock)
  • Fuses related to convenience circuits blowing or showing damage
  • Erratic central locking behavior or locks cycling
  • Associated DTCs related to door modules or BCM communication
  • Instrument cluster or warning light related to vehicle security or convenience

What to check

  • Retrieve freeze-frame and full DTC list with a capable diagnostic tool; note any related codes
  • Visually inspect wiring harnesses at doors, hinges, door modules and BCM for damage, pinched wires, corrosion or water
  • Inspect connectors for corrosion, bent pins, moisture, or debris at BCM and door/module
  • Check fuses and fusible links for the convenience/keyless circuits
  • Check for aftermarket alarm/remote installations and inspect their wiring
  • Perform wiggle test of door harness while monitoring signal or checking for fault recreation

Signal parameters

  • Expected: Key entry/lock input should be high-impedance when inactive (no continuity to ground).
  • Expected: When switch is activated, the module sees the appropriate feed voltage or a defined switch-to-ground depending on design (refer to factory wiring).
  • Fault indication: Continuity to chassis ground measured at the input connector (
  • Voltage check: Backprobe input — should not read a solid 0 V to ground when system is inactive unless design dictates; consult OEM wiring diagrams for exact states.

Diagnostic algorithm

  1. Connect a diagnostic scan tool, read and record all codes and freeze-frame data. Clear codes and see if C1748 returns.
  2. Visually inspect door harnesses, grommets and connector bodies for damage or water. Repair obvious damage.
  3. With ignition off, disconnect the BCM/door module connector(s). Measure continuity from the suspected key entry input pin to chassis ground. If
  4. If continuity present, isolate sections of the circuit by disconnecting door modules, actuators, switches, and aftermarket devices one at a time until the short clears to identify the faulty component or splice.
  5. If no wiring short is found, reconnect modules and backprobe the signal while operating the key entry or switch to observe voltage changes with a multimeter or scope. Compare against OEM values.
  6. Inspect and test related fuses and ground points; clean/repair grounds as necessary and re-tighten connections.
  7. If wiring and connectors test OK and no external load is causing the short, consider replacing the suspect module (door module/BCM) only after confirming module fault via substitution or bench test per manufacturer procedures.
  8. After repair, clear codes, perform function test and road test as required to verify the issue is resolved.

Likely causes

  • Chafed insulation where wiring passes through door hinge or body
  • Corrosion inside the connector at the door module or BCM
  • Door lock actuator or interior lock switch failed shorted to ground
  • Aftermarket device tied into key entry circuit creating a ground path
  • Module failure (BCM/door module) with internal short

Fault status

⚠️ Status
Key entry circuit short to ground detected by Body Control Module; input is being pulled to chassis ground.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

Similar codes

C1747 C1750 C1730 U0121 B1210
320

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

LAND ROVER

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Code

C1748

Other C — Chassis

Switch input Circuit Short to Gnd

Brand: Other
Type: C — Chassis
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged wiring harness with exposed conductor contacting chassis ground
  • Corroded or contaminated connector at BCM or door module
  • Failed keyless entry switch, door lock actuator, or microswitch internally shorted to ground
  • Water ingress in door or module causing a short
  • Aftermarket alarm or remote start improperly wired
  • Faulty BCM or door control module internal short

Symptoms

  • Keyless/key entry operation inoperative or intermittent (no lock/unlock)
  • Fuses related to convenience circuits blowing or showing damage
  • Erratic central locking behavior or locks cycling
  • Associated DTCs related to door modules or BCM communication
  • Instrument cluster or warning light related to vehicle security or convenience

What to check

  • Retrieve freeze-frame and full DTC list with a capable diagnostic tool; note any related codes
  • Visually inspect wiring harnesses at doors, hinges, door modules and BCM for damage, pinched wires, corrosion or water
  • Inspect connectors for corrosion, bent pins, moisture, or debris at BCM and door/module
  • Check fuses and fusible links for the convenience/keyless circuits
  • Check for aftermarket alarm/remote installations and inspect their wiring
  • Perform wiggle test of door harness while monitoring signal or checking for fault recreation

Signal parameters

  • Expected: Key entry/lock input should be high-impedance when inactive (no continuity to ground).
  • Expected: When switch is activated, the module sees the appropriate feed voltage or a defined switch-to-ground depending on design (refer to factory wiring).
  • Fault indication: Continuity to chassis ground measured at the input connector (
  • Voltage check: Backprobe input — should not read a solid 0 V to ground when system is inactive unless design dictates; consult OEM wiring diagrams for exact states.

Diagnostic algorithm

  1. Connect a diagnostic scan tool, read and record all codes and freeze-frame data. Clear codes and see if C1748 returns.
  2. Visually inspect door harnesses, grommets and connector bodies for damage or water. Repair obvious damage.
  3. With ignition off, disconnect the BCM/door module connector(s). Measure continuity from the suspected key entry input pin to chassis ground. If
  4. If continuity present, isolate sections of the circuit by disconnecting door modules, actuators, switches, and aftermarket devices one at a time until the short clears to identify the faulty component or splice.
  5. If no wiring short is found, reconnect modules and backprobe the signal while operating the key entry or switch to observe voltage changes with a multimeter or scope. Compare against OEM values.
  6. Inspect and test related fuses and ground points; clean/repair grounds as necessary and re-tighten connections.
  7. If wiring and connectors test OK and no external load is causing the short, consider replacing the suspect module (door module/BCM) only after confirming module fault via substitution or bench test per manufacturer procedures.
  8. After repair, clear codes, perform function test and road test as required to verify the issue is resolved.

Likely causes

  • Chafed insulation where wiring passes through door hinge or body
  • Corrosion inside the connector at the door module or BCM
  • Door lock actuator or interior lock switch failed shorted to ground
  • Aftermarket device tied into key entry circuit creating a ground path
  • Module failure (BCM/door module) with internal short

Fault status

⚠️ Status
Key entry circuit short to ground detected by Body Control Module; input is being pulled to chassis ground.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1-3 hours

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C1747 C1750 C1730 U0121 B1210
7,754

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