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Home / DTC / B2587 — Park Lamp Relay Output Circuit Low (BCM)

B2587 — Park Lamp Relay Output Circuit Low (BCM)

Detailed page for trouble code B2587.

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59brands
11,914generic
22,491specific
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Code

B2587

HUMMER B — Body

Park Lamp Relay Output Circuit Low (BCM)

Brand: HUMMER
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to ground on the park lamp relay control or output circuit
  • Open or high-resistance wiring/connectors between BCM and relay/lamp circuit
  • Failed park lamp relay or relay socket corrosion
  • Blown fuse or poor fuse/relay connection
  • Failed BCM output transistor or internal BCM fault
  • Damaged lamp bulbs or shorted bulb socket

Symptoms

  • Parking/park lamps do not illuminate or are intermittent
  • Low or no voltage present at park lamp relay output
  • Fuses related to exterior lighting may be blown
  • Other body lighting features controlled by the same BCM may be affected
  • Possible flicker or dim lights

What to check

  • Scan for stored codes and freeze frame data; note related network or lighting codes
  • Visually inspect fuse(s) and related relay for corrosion, heat discoloration, or blown element
  • Inspect wiring harness and connectors for damage, corrosion, loose pins, or aftermarket taps
  • Check for proper seating of the park lamp relay and condition of relay socket
  • Measure voltage at the relay control terminal (BCM output) with connector attached and with relay installed/removed
  • Measure voltage at the relay output that feeds the lamps (lamp feed) with lamps switched on

Signal parameters

  • Expected relay control/output: inactive ≈ 0 V; active ≈ battery voltage (typically 11–14.5 V)
  • Relay coil current: typically a few hundred milliamps (varies by relay); verify spec for replacement relay
  • BCM input/output diagnostic threshold: circuit considered low when voltage is significantly below battery voltage under commanded ON
  • Resistance: relay coil bench resistance typically tens to a few hundred ohms (check replacement relay spec)

Diagnostic algorithm

  1. Verify the DTC and note when it was set. Check for any additional lighting or BCM-related codes.
  2. Visually inspect fuses, relay, relay socket, connectors and associated wiring for obvious damage or corrosion. Repair as needed.
  3. With park lamp switch OFF then ON, use a DVOM to measure voltage at the park lamp relay control terminal (BCM side) and at the relay output to the lamps. Compare to battery voltage.
  4. Remove the relay and bench-test the relay coil and contacts (apply battery to the coil and confirm contact closure). Replace relay if faulty.
  5. If relay tests good but control terminal remains low when commanded ON, probe wiring between the BCM and relay for short to ground or open. Backprobing may be required per service manual.
  6. Check continuity to ground of the lamp feed and measure resistance from lamp feed to battery to detect shorting at lamp sockets or damaged wires.
  7. Repair any shorts, open circuits, corroded connectors, or poor grounds. Reinspect any aftermarket connections and remove if necessary.
  8. If wiring, relay, and lamps check good and the BCM still reports a low output, consult service information for BCM diagnostics — attempt software reflash/reset per procedures before replacing the module.
  9. Clear codes and functional test the park lamp circuit multiple cycles to confirm repair.

Likely causes

  • Corroded or loose relay socket/connector at park lamp relay
  • Wire chafe or pinched conductor creating a short to ground
  • Failed park lamp relay coil or contact
  • Blown fuse protecting park lamp circuit
  • BCM output driver failure (less common than wiring/relay problems)

Fault status

⚠️ Status
Park Lamp Relay Output Circuit Low (BCM) — BCM has detected an abnormally low voltage/signal on the park lamp relay control or output circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 2.5 hours

Similar codes

B2586 B2588 B2590 U0100 U0121
Repair manuals

Manual library for HUMMER

138

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Code

B2587

HYUNDAI B — Body

Back Up Lamp Short to Ground

Brand: HYUNDAI
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to ground on the park lamp relay control or output circuit
  • Open or high-resistance wiring/connectors between BCM and relay/lamp circuit
  • Failed park lamp relay or relay socket corrosion
  • Blown fuse or poor fuse/relay connection
  • Failed BCM output transistor or internal BCM fault
  • Damaged lamp bulbs or shorted bulb socket

Symptoms

  • Parking/park lamps do not illuminate or are intermittent
  • Low or no voltage present at park lamp relay output
  • Fuses related to exterior lighting may be blown
  • Other body lighting features controlled by the same BCM may be affected
  • Possible flicker or dim lights

What to check

  • Scan for stored codes and freeze frame data; note related network or lighting codes
  • Visually inspect fuse(s) and related relay for corrosion, heat discoloration, or blown element
  • Inspect wiring harness and connectors for damage, corrosion, loose pins, or aftermarket taps
  • Check for proper seating of the park lamp relay and condition of relay socket
  • Measure voltage at the relay control terminal (BCM output) with connector attached and with relay installed/removed
  • Measure voltage at the relay output that feeds the lamps (lamp feed) with lamps switched on

Signal parameters

  • Expected relay control/output: inactive ≈ 0 V; active ≈ battery voltage (typically 11–14.5 V)
  • Relay coil current: typically a few hundred milliamps (varies by relay); verify spec for replacement relay
  • BCM input/output diagnostic threshold: circuit considered low when voltage is significantly below battery voltage under commanded ON
  • Resistance: relay coil bench resistance typically tens to a few hundred ohms (check replacement relay spec)

Diagnostic algorithm

  1. Verify the DTC and note when it was set. Check for any additional lighting or BCM-related codes.
  2. Visually inspect fuses, relay, relay socket, connectors and associated wiring for obvious damage or corrosion. Repair as needed.
  3. With park lamp switch OFF then ON, use a DVOM to measure voltage at the park lamp relay control terminal (BCM side) and at the relay output to the lamps. Compare to battery voltage.
  4. Remove the relay and bench-test the relay coil and contacts (apply battery to the coil and confirm contact closure). Replace relay if faulty.
  5. If relay tests good but control terminal remains low when commanded ON, probe wiring between the BCM and relay for short to ground or open. Backprobing may be required per service manual.
  6. Check continuity to ground of the lamp feed and measure resistance from lamp feed to battery to detect shorting at lamp sockets or damaged wires.
  7. Repair any shorts, open circuits, corroded connectors, or poor grounds. Reinspect any aftermarket connections and remove if necessary.
  8. If wiring, relay, and lamps check good and the BCM still reports a low output, consult service information for BCM diagnostics — attempt software reflash/reset per procedures before replacing the module.
  9. Clear codes and functional test the park lamp circuit multiple cycles to confirm repair.

Likely causes

  • Corroded or loose relay socket/connector at park lamp relay
  • Wire chafe or pinched conductor creating a short to ground
  • Failed park lamp relay coil or contact
  • Blown fuse protecting park lamp circuit
  • BCM output driver failure (less common than wiring/relay problems)

Fault status

⚠️ Status
Park Lamp Relay Output Circuit Low (BCM) — BCM has detected an abnormally low voltage/signal on the park lamp relay control or output circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 2.5 hours

Similar codes

B2586 B2588 B2590 U0100 U0121
371

Browse 371 HYUNDAI manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.

HYUNDAI

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Code

B2587

Other B — Body

Passenger Seat Occupant Detection Circuit Short To Battery

Brand: Other
Type: B — Body
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Short to ground on the park lamp relay control or output circuit
  • Open or high-resistance wiring/connectors between BCM and relay/lamp circuit
  • Failed park lamp relay or relay socket corrosion
  • Blown fuse or poor fuse/relay connection
  • Failed BCM output transistor or internal BCM fault
  • Damaged lamp bulbs or shorted bulb socket

Symptoms

  • Parking/park lamps do not illuminate or are intermittent
  • Low or no voltage present at park lamp relay output
  • Fuses related to exterior lighting may be blown
  • Other body lighting features controlled by the same BCM may be affected
  • Possible flicker or dim lights

What to check

  • Scan for stored codes and freeze frame data; note related network or lighting codes
  • Visually inspect fuse(s) and related relay for corrosion, heat discoloration, or blown element
  • Inspect wiring harness and connectors for damage, corrosion, loose pins, or aftermarket taps
  • Check for proper seating of the park lamp relay and condition of relay socket
  • Measure voltage at the relay control terminal (BCM output) with connector attached and with relay installed/removed
  • Measure voltage at the relay output that feeds the lamps (lamp feed) with lamps switched on

Signal parameters

  • Expected relay control/output: inactive ≈ 0 V; active ≈ battery voltage (typically 11–14.5 V)
  • Relay coil current: typically a few hundred milliamps (varies by relay); verify spec for replacement relay
  • BCM input/output diagnostic threshold: circuit considered low when voltage is significantly below battery voltage under commanded ON
  • Resistance: relay coil bench resistance typically tens to a few hundred ohms (check replacement relay spec)

Diagnostic algorithm

  1. Verify the DTC and note when it was set. Check for any additional lighting or BCM-related codes.
  2. Visually inspect fuses, relay, relay socket, connectors and associated wiring for obvious damage or corrosion. Repair as needed.
  3. With park lamp switch OFF then ON, use a DVOM to measure voltage at the park lamp relay control terminal (BCM side) and at the relay output to the lamps. Compare to battery voltage.
  4. Remove the relay and bench-test the relay coil and contacts (apply battery to the coil and confirm contact closure). Replace relay if faulty.
  5. If relay tests good but control terminal remains low when commanded ON, probe wiring between the BCM and relay for short to ground or open. Backprobing may be required per service manual.
  6. Check continuity to ground of the lamp feed and measure resistance from lamp feed to battery to detect shorting at lamp sockets or damaged wires.
  7. Repair any shorts, open circuits, corroded connectors, or poor grounds. Reinspect any aftermarket connections and remove if necessary.
  8. If wiring, relay, and lamps check good and the BCM still reports a low output, consult service information for BCM diagnostics — attempt software reflash/reset per procedures before replacing the module.
  9. Clear codes and functional test the park lamp circuit multiple cycles to confirm repair.

Likely causes

  • Corroded or loose relay socket/connector at park lamp relay
  • Wire chafe or pinched conductor creating a short to ground
  • Failed park lamp relay coil or contact
  • Blown fuse protecting park lamp circuit
  • BCM output driver failure (less common than wiring/relay problems)

Fault status

⚠️ Status
Park Lamp Relay Output Circuit Low (BCM) — BCM has detected an abnormally low voltage/signal on the park lamp relay control or output circuit.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.0 - 2.5 hours

Similar codes

B2586 B2588 B2590 U0100 U0121
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