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C1225 — Lamp Brake Warning Output Circuit Short To Battery

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Code

C1225

Generic C — Chassis

Lamp Brake Warning Output Circuit Short To Battery

Brand: Generic
Views: UK: 19 EN: 41 RU: 26
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or chafed wiring in the brake warning lamp output circuit creating a short to battery
  • Corroded or bridged connector or socket at the instrument cluster or lamp assembly
  • Failed brake-warn lamp bulb or LED driver internally shorted to battery
  • Stuck/shorted relay or fused feed providing battery voltage to the output when it should be open
  • Faulty body control module (BCM) / ABS module or internal driver transistor failure
  • Aftermarket accessories improperly wired into the lighting circuit

Symptoms

  • Brake warning lamp (and possibly related warning indicators) illuminated continuously
  • Brake warning lamp does not respond to ignition or brake switch changes (stays on)
  • Intermittent or constant battery drain in some cases
  • Possible multiple related warning lamps if BCM shares circuits

What to check

  • Retrieve freeze frame and stored codes from BCM/ABS/instrument cluster and note occurrence conditions
  • Perform visual inspection of instrument cluster connector, fuse box, lamp sockets, and visible wiring harnesses for damage or corrosion
  • Check for aftermarket devices connected to lighting or brake circuits
  • With ignition ON, measure voltage at the brake-warn output pin at the controlling module and at the lamp connector
  • Disconnect the lamp/cluster connector and see if code clears or voltage changes to isolate load vs driver issue
  • Inspect and test related fuses and relays for stuck contacts

Signal parameters

  • Expected: With circuit inactive, driver output should be open/low (approx. 0–1 V) or high-impedance; with lamp commanded ON it should present battery voltage (~11–14.5 V) through lamp load
  • Fault present: steady battery voltage (~12 V) measured at the output when lamp should be OFF
  • Typical lamp load: incandescent filaments show low resistance (~1–30 Ω depending on bulb); LED modules may show higher or electronic loads — consult vehicle wiring diagram

Diagnostic algorithm

  1. Read and record all stored codes and readiness status from BCM/ABS/instrument cluster.
  2. Reproduce fault if possible and note when it occurs (key position, braking, doors, unlock).
  3. Visually inspect wiring, connectors, and lamp sockets for damage, corrosion, or signs of shorting; repair as needed.
  4. Disconnect the brake-warn lamp connector at the instrument cluster or lamp assembly. Clear the code and cycle ignition. If the code does not return, the short is in the wiring or lamp assembly downstream of the connector.
  5. With connector disconnected and ignition ON, backprobe the module output pin. Measure voltage: if ~12 V with connector disconnected, the module output is being fed by battery (short) or the module driver has failed. If low/0 V with connector disconnected but rises when connector is attached, suspect lamp/connector or downstream short.
  6. Isolate wiring by disconnecting intermediate connectors or removing lamp sockets until the short is localized. Use a fused jumper or test light to prevent damage during checks.
  7. If wiring and lamp assembly are verified OK, replace or repair the controlling module per manufacturer procedure. Verify replacement resolves code.
  8. After repairs, clear codes and perform road/operation test to confirm the fault does not return.

Likely causes

  • Shorted wiring or pin terminal at instrument cluster connector
  • Corroded lamp socket or passenger compartment connector causing positive feed to appear on the output circuit
  • Faulty instrument cluster/BCM output driver (replace only after wiring is verified)
  • Bulb or LED module failure with internal short

Fault status

⚠️ Status
Brake warning lamp output circuit short to battery detected — the output is seeing battery voltage when it should be off. Inspect wiring, connectors, lamp(s), and controlling module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

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Code

C1225

HUMMER C — Chassis

Left Front Excessive Wheel Speed Variation

Brand: HUMMER
Views: UK: 13 EN: 25 RU: 16
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or chafed wiring in the brake warning lamp output circuit creating a short to battery
  • Corroded or bridged connector or socket at the instrument cluster or lamp assembly
  • Failed brake-warn lamp bulb or LED driver internally shorted to battery
  • Stuck/shorted relay or fused feed providing battery voltage to the output when it should be open
  • Faulty body control module (BCM) / ABS module or internal driver transistor failure
  • Aftermarket accessories improperly wired into the lighting circuit

Symptoms

  • Brake warning lamp (and possibly related warning indicators) illuminated continuously
  • Brake warning lamp does not respond to ignition or brake switch changes (stays on)
  • Intermittent or constant battery drain in some cases
  • Possible multiple related warning lamps if BCM shares circuits

What to check

  • Retrieve freeze frame and stored codes from BCM/ABS/instrument cluster and note occurrence conditions
  • Perform visual inspection of instrument cluster connector, fuse box, lamp sockets, and visible wiring harnesses for damage or corrosion
  • Check for aftermarket devices connected to lighting or brake circuits
  • With ignition ON, measure voltage at the brake-warn output pin at the controlling module and at the lamp connector
  • Disconnect the lamp/cluster connector and see if code clears or voltage changes to isolate load vs driver issue
  • Inspect and test related fuses and relays for stuck contacts

Signal parameters

  • Expected: With circuit inactive, driver output should be open/low (approx. 0–1 V) or high-impedance; with lamp commanded ON it should present battery voltage (~11–14.5 V) through lamp load
  • Fault present: steady battery voltage (~12 V) measured at the output when lamp should be OFF
  • Typical lamp load: incandescent filaments show low resistance (~1–30 Ω depending on bulb); LED modules may show higher or electronic loads — consult vehicle wiring diagram

Diagnostic algorithm

  1. Read and record all stored codes and readiness status from BCM/ABS/instrument cluster.
  2. Reproduce fault if possible and note when it occurs (key position, braking, doors, unlock).
  3. Visually inspect wiring, connectors, and lamp sockets for damage, corrosion, or signs of shorting; repair as needed.
  4. Disconnect the brake-warn lamp connector at the instrument cluster or lamp assembly. Clear the code and cycle ignition. If the code does not return, the short is in the wiring or lamp assembly downstream of the connector.
  5. With connector disconnected and ignition ON, backprobe the module output pin. Measure voltage: if ~12 V with connector disconnected, the module output is being fed by battery (short) or the module driver has failed. If low/0 V with connector disconnected but rises when connector is attached, suspect lamp/connector or downstream short.
  6. Isolate wiring by disconnecting intermediate connectors or removing lamp sockets until the short is localized. Use a fused jumper or test light to prevent damage during checks.
  7. If wiring and lamp assembly are verified OK, replace or repair the controlling module per manufacturer procedure. Verify replacement resolves code.
  8. After repairs, clear codes and perform road/operation test to confirm the fault does not return.

Likely causes

  • Shorted wiring or pin terminal at instrument cluster connector
  • Corroded lamp socket or passenger compartment connector causing positive feed to appear on the output circuit
  • Faulty instrument cluster/BCM output driver (replace only after wiring is verified)
  • Bulb or LED module failure with internal short

Fault status

⚠️ Status
Brake warning lamp output circuit short to battery detected — the output is seeing battery voltage when it should be off. Inspect wiring, connectors, lamp(s), and controlling module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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Code

C1225

HYUNDAI C — Chassis

ASC Potentiometer - Low Input

Brand: HYUNDAI
Views: UK: 16 EN: 23 RU: 16
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or chafed wiring in the brake warning lamp output circuit creating a short to battery
  • Corroded or bridged connector or socket at the instrument cluster or lamp assembly
  • Failed brake-warn lamp bulb or LED driver internally shorted to battery
  • Stuck/shorted relay or fused feed providing battery voltage to the output when it should be open
  • Faulty body control module (BCM) / ABS module or internal driver transistor failure
  • Aftermarket accessories improperly wired into the lighting circuit

Symptoms

  • Brake warning lamp (and possibly related warning indicators) illuminated continuously
  • Brake warning lamp does not respond to ignition or brake switch changes (stays on)
  • Intermittent or constant battery drain in some cases
  • Possible multiple related warning lamps if BCM shares circuits

What to check

  • Retrieve freeze frame and stored codes from BCM/ABS/instrument cluster and note occurrence conditions
  • Perform visual inspection of instrument cluster connector, fuse box, lamp sockets, and visible wiring harnesses for damage or corrosion
  • Check for aftermarket devices connected to lighting or brake circuits
  • With ignition ON, measure voltage at the brake-warn output pin at the controlling module and at the lamp connector
  • Disconnect the lamp/cluster connector and see if code clears or voltage changes to isolate load vs driver issue
  • Inspect and test related fuses and relays for stuck contacts

Signal parameters

  • Expected: With circuit inactive, driver output should be open/low (approx. 0–1 V) or high-impedance; with lamp commanded ON it should present battery voltage (~11–14.5 V) through lamp load
  • Fault present: steady battery voltage (~12 V) measured at the output when lamp should be OFF
  • Typical lamp load: incandescent filaments show low resistance (~1–30 Ω depending on bulb); LED modules may show higher or electronic loads — consult vehicle wiring diagram

Diagnostic algorithm

  1. Read and record all stored codes and readiness status from BCM/ABS/instrument cluster.
  2. Reproduce fault if possible and note when it occurs (key position, braking, doors, unlock).
  3. Visually inspect wiring, connectors, and lamp sockets for damage, corrosion, or signs of shorting; repair as needed.
  4. Disconnect the brake-warn lamp connector at the instrument cluster or lamp assembly. Clear the code and cycle ignition. If the code does not return, the short is in the wiring or lamp assembly downstream of the connector.
  5. With connector disconnected and ignition ON, backprobe the module output pin. Measure voltage: if ~12 V with connector disconnected, the module output is being fed by battery (short) or the module driver has failed. If low/0 V with connector disconnected but rises when connector is attached, suspect lamp/connector or downstream short.
  6. Isolate wiring by disconnecting intermediate connectors or removing lamp sockets until the short is localized. Use a fused jumper or test light to prevent damage during checks.
  7. If wiring and lamp assembly are verified OK, replace or repair the controlling module per manufacturer procedure. Verify replacement resolves code.
  8. After repairs, clear codes and perform road/operation test to confirm the fault does not return.

Likely causes

  • Shorted wiring or pin terminal at instrument cluster connector
  • Corroded lamp socket or passenger compartment connector causing positive feed to appear on the output circuit
  • Faulty instrument cluster/BCM output driver (replace only after wiring is verified)
  • Bulb or LED module failure with internal short

Fault status

⚠️ Status
Brake warning lamp output circuit short to battery detected — the output is seeing battery voltage when it should be off. Inspect wiring, connectors, lamp(s), and controlling module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

Similar codes

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+100 karma for a short comment :)
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Code

C1225

MITSUBISHI C — Chassis

Deviation between wheel speed

Brand: MITSUBISHI
Views: UK: 10 EN: 19 RU: 13
AI status
Completed
ready
Completed 100%
Page language: EN

Causes

  • Damaged or chafed wiring in the brake warning lamp output circuit creating a short to battery
  • Corroded or bridged connector or socket at the instrument cluster or lamp assembly
  • Failed brake-warn lamp bulb or LED driver internally shorted to battery
  • Stuck/shorted relay or fused feed providing battery voltage to the output when it should be open
  • Faulty body control module (BCM) / ABS module or internal driver transistor failure
  • Aftermarket accessories improperly wired into the lighting circuit

Symptoms

  • Brake warning lamp (and possibly related warning indicators) illuminated continuously
  • Brake warning lamp does not respond to ignition or brake switch changes (stays on)
  • Intermittent or constant battery drain in some cases
  • Possible multiple related warning lamps if BCM shares circuits

What to check

  • Retrieve freeze frame and stored codes from BCM/ABS/instrument cluster and note occurrence conditions
  • Perform visual inspection of instrument cluster connector, fuse box, lamp sockets, and visible wiring harnesses for damage or corrosion
  • Check for aftermarket devices connected to lighting or brake circuits
  • With ignition ON, measure voltage at the brake-warn output pin at the controlling module and at the lamp connector
  • Disconnect the lamp/cluster connector and see if code clears or voltage changes to isolate load vs driver issue
  • Inspect and test related fuses and relays for stuck contacts

Signal parameters

  • Expected: With circuit inactive, driver output should be open/low (approx. 0–1 V) or high-impedance; with lamp commanded ON it should present battery voltage (~11–14.5 V) through lamp load
  • Fault present: steady battery voltage (~12 V) measured at the output when lamp should be OFF
  • Typical lamp load: incandescent filaments show low resistance (~1–30 Ω depending on bulb); LED modules may show higher or electronic loads — consult vehicle wiring diagram

Diagnostic algorithm

  1. Read and record all stored codes and readiness status from BCM/ABS/instrument cluster.
  2. Reproduce fault if possible and note when it occurs (key position, braking, doors, unlock).
  3. Visually inspect wiring, connectors, and lamp sockets for damage, corrosion, or signs of shorting; repair as needed.
  4. Disconnect the brake-warn lamp connector at the instrument cluster or lamp assembly. Clear the code and cycle ignition. If the code does not return, the short is in the wiring or lamp assembly downstream of the connector.
  5. With connector disconnected and ignition ON, backprobe the module output pin. Measure voltage: if ~12 V with connector disconnected, the module output is being fed by battery (short) or the module driver has failed. If low/0 V with connector disconnected but rises when connector is attached, suspect lamp/connector or downstream short.
  6. Isolate wiring by disconnecting intermediate connectors or removing lamp sockets until the short is localized. Use a fused jumper or test light to prevent damage during checks.
  7. If wiring and lamp assembly are verified OK, replace or repair the controlling module per manufacturer procedure. Verify replacement resolves code.
  8. After repairs, clear codes and perform road/operation test to confirm the fault does not return.

Likely causes

  • Shorted wiring or pin terminal at instrument cluster connector
  • Corroded lamp socket or passenger compartment connector causing positive feed to appear on the output circuit
  • Faulty instrument cluster/BCM output driver (replace only after wiring is verified)
  • Bulb or LED module failure with internal short

Fault status

⚠️ Status
Brake warning lamp output circuit short to battery detected — the output is seeing battery voltage when it should be off. Inspect wiring, connectors, lamp(s), and controlling module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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Code

C1225

Other C — Chassis

Lamp Brake Warning Output Circuit Short To Battery

Brand: Other
Views: UK: 24 EN: 37 RU: 33
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Causes

  • Damaged or chafed wiring in the brake warning lamp output circuit creating a short to battery
  • Corroded or bridged connector or socket at the instrument cluster or lamp assembly
  • Failed brake-warn lamp bulb or LED driver internally shorted to battery
  • Stuck/shorted relay or fused feed providing battery voltage to the output when it should be open
  • Faulty body control module (BCM) / ABS module or internal driver transistor failure
  • Aftermarket accessories improperly wired into the lighting circuit

Symptoms

  • Brake warning lamp (and possibly related warning indicators) illuminated continuously
  • Brake warning lamp does not respond to ignition or brake switch changes (stays on)
  • Intermittent or constant battery drain in some cases
  • Possible multiple related warning lamps if BCM shares circuits

What to check

  • Retrieve freeze frame and stored codes from BCM/ABS/instrument cluster and note occurrence conditions
  • Perform visual inspection of instrument cluster connector, fuse box, lamp sockets, and visible wiring harnesses for damage or corrosion
  • Check for aftermarket devices connected to lighting or brake circuits
  • With ignition ON, measure voltage at the brake-warn output pin at the controlling module and at the lamp connector
  • Disconnect the lamp/cluster connector and see if code clears or voltage changes to isolate load vs driver issue
  • Inspect and test related fuses and relays for stuck contacts

Signal parameters

  • Expected: With circuit inactive, driver output should be open/low (approx. 0–1 V) or high-impedance; with lamp commanded ON it should present battery voltage (~11–14.5 V) through lamp load
  • Fault present: steady battery voltage (~12 V) measured at the output when lamp should be OFF
  • Typical lamp load: incandescent filaments show low resistance (~1–30 Ω depending on bulb); LED modules may show higher or electronic loads — consult vehicle wiring diagram

Diagnostic algorithm

  1. Read and record all stored codes and readiness status from BCM/ABS/instrument cluster.
  2. Reproduce fault if possible and note when it occurs (key position, braking, doors, unlock).
  3. Visually inspect wiring, connectors, and lamp sockets for damage, corrosion, or signs of shorting; repair as needed.
  4. Disconnect the brake-warn lamp connector at the instrument cluster or lamp assembly. Clear the code and cycle ignition. If the code does not return, the short is in the wiring or lamp assembly downstream of the connector.
  5. With connector disconnected and ignition ON, backprobe the module output pin. Measure voltage: if ~12 V with connector disconnected, the module output is being fed by battery (short) or the module driver has failed. If low/0 V with connector disconnected but rises when connector is attached, suspect lamp/connector or downstream short.
  6. Isolate wiring by disconnecting intermediate connectors or removing lamp sockets until the short is localized. Use a fused jumper or test light to prevent damage during checks.
  7. If wiring and lamp assembly are verified OK, replace or repair the controlling module per manufacturer procedure. Verify replacement resolves code.
  8. After repairs, clear codes and perform road/operation test to confirm the fault does not return.

Likely causes

  • Shorted wiring or pin terminal at instrument cluster connector
  • Corroded lamp socket or passenger compartment connector causing positive feed to appear on the output circuit
  • Faulty instrument cluster/BCM output driver (replace only after wiring is verified)
  • Bulb or LED module failure with internal short

Fault status

⚠️ Status
Brake warning lamp output circuit short to battery detected — the output is seeing battery voltage when it should be off. Inspect wiring, connectors, lamp(s), and controlling module.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-2.0 hours

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