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Home / DTC / B0729 — P (park) Indicator Circuit Open (BCM)

B0729 — P (park) Indicator Circuit Open (BCM)

Detailed page for trouble code B0729.

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Code

B0729

HUMMER B — Body

P (park) Indicator Circuit Open (BCM)

Brand: HUMMER
Type: B — Body
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Page language: EN

Causes

  • Open or broken wiring between BCM and instrument cluster lamp/LED
  • Corroded or loose connector at BCM or instrument cluster
  • Failed lamp bulb or LED element in the instrument cluster
  • Blown fuse supplying the instrument cluster or BCM output
  • BCM output driver (internal transistor) failure
  • Recent aftermarket electrical work or modifications interfering with the circuit

Symptoms

  • 'P' (Park) indicator on instrument cluster will not illuminate
  • Instrument cluster self-test may show missing/failed Park lamp
  • Possible stored BCM or cluster related codes
  • No drivability effect, but loss of Park indicator visibility

What to check

  • Retrieve stored codes and freeze frame data with a scan tool; note any related body or cluster codes
  • Perform instrument cluster self-test to confirm Park lamp does not light
  • Visually inspect wiring and connectors between BCM and instrument cluster for damage or corrosion
  • Check related fuses for the instrument cluster/BCM
  • Backprobe the Park indicator connector with ignition ON and during self-test to confirm voltage presence
  • Check continuity between the BCM output pin and the cluster lamp pin with ignition OFF

Signal parameters

  • Expected: ~12 V (or battery voltage) present at the Park indicator lamp feed when BCM commands lamp ON
  • Expected continuity: low ohms between BCM output pin and cluster lamp pin (near 0–5 Ω for short harnesses)
  • Open circuit: infinite resistance (OL) between BCM output and lamp
  • No voltage with ignition off; switched or grounded depending on design when off
  • CAN/BCM data: Park gear state and lamp command present over network when applicable

Diagnostic algorithm

  1. Connect scan tool, record B0729 and any related codes, clear codes and see if it returns.
  2. Perform cluster self-test to verify 'P' lamp failure. If the lamp lights during self-test, suspect control circuit rather than lamp.
  3. Inspect fuses and relays for the instrument cluster and BCM power. Replace any blown fuses and retest.
  4. Visually inspect connectors and wiring between the BCM and instrument cluster for damage, corrosion, or disconnected pins. Repair as needed.
  5. With ignition OFF, disconnect battery negative (if required by workshop safety procedures) before performing continuity checks. With ignition ON for voltage checks, backprobe the harness at the cluster and at the BCM connector to verify voltage and continuity. Compare to expected values in signal_params.
  6. If lamp/LED is removable, test or replace the lamp assembly to rule out failed bulb/LED.
  7. If wiring and lamp are good but no BCM output is present, check BCM grounds and supply voltages. If supplies and grounds are good, suspect BCM output driver fault.
  8. To confirm BCM fault, if available, substitute a known-good BCM or perform bench/diagnostic module tests per manufacturer procedures. Reprogram or replace BCM only after confirming external circuit integrity.
  9. After repair, clear codes and perform function test and road test as required to ensure code does not return.

Likely causes

  • Broken/disconnected harness or connector between BCM and cluster
  • Failed cluster lamp/LED (burned out)
  • Corroded connector contact causing open circuit
  • Blown fuse or fusible link on the cluster supply
  • BCM internal output fault (less common)

Fault status

⚠️ Status
Park Indicator Circuit Open — BCM detects open circuit on Park (P) indicator lamp circuit. Park indicator may not illuminate.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-1.5 hours

Similar codes

B0728 B0730 B0200 U0121 B1234
Repair manuals

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