B1215

Code

Other B — Body

Running Board Lamp Circuit Short to Battery

Brand: Other

Type: B — Body

Views: UK: 92 EN: 89 RU: 120

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Damaged wiring insulation allowing power conductor to contact battery feed or fused power rail
Pinched or chafed harness at door hinge, body seam or undercarriage near running board
Corroded or water-intruded lamp connector or lamp module causing internal short
Faulty running board lamp (LED module or incandescent) with internal short
Failed switch, relay, or body control module (BCM) providing constant battery feed
Aftermarket accessories or prior repairs introduced an improper splice or fused tap

Symptoms

Running board lamp remains ON with switch OFF
Lamp fuse blows repeatedly or circuit breaker trips
Battery drains when vehicle is parked
Related body module shows lamp circuit fault or warning
Intermittent lamp operation when vehicle or doors move

What to check

Visually inspect running board lamp, connectors and wiring for damage, corrosion or water entry
Check fuse for the lamp circuit and note if fuse is blown or appears heat-damaged
With ignition off, check if running board lamp is energized (lamp lit or voltage at lamp connector)
Use a DVOM to measure voltage at the lamp connector with switch OFF — presence of battery voltage indicates short to battery
Wiggle harness around door hinge and running board while monitoring lamp/voltage to reproduce an intermittent short
Disconnect running board lamp connector; if the lamp turns off and code clears or fuse no longer blows, the lamp or connector is likely at fault

Signal parameters

Lamp circuit voltage with switch OFF: should be ~0 V or open; short-to-battery condition shows ~12 V (battery voltage) present
Lamp circuit voltage with switch ON: should be ~12 V (battery voltage) at lamp positive and chassis ground at negative
Expected lamp current: nominal draw for the specific lamp type (LED modules typically low current; incandescent higher) — excessive current indicates short or lamp failure
Continuity: power feed to lamp should be open with switch OFF; short-to-battery shows continuity to battery positive with switch OFF

Diagnostic algorithm

Retrieve freeze frame/snapshot and note conditions when the code set (key on/off, door position, lamp state).
Visually inspect lamp assembly, lens, mounting, harness, and connectors for damage, corrosion or water entry. Repair or replace as required.
Check related fuses and fusible links; replace blown fuse and attempt to reproduce fault under supervision. Do not drive with repeated fuse replacement until root cause found.
With connector accessible, backprobing: measure voltage at lamp power pin with switch OFF. If ~12 V present, trace upstream for splice or feed tying into battery. If 0 V, disconnect lamp and check lamp resistance/short to ground.
Disconnect the running board lamp connector. If fault clears and fuse no longer blows, bench-test the lamp module for internal short; replace lamp if defective.
If lamp and connector are good, trace wiring back toward the junction/BCM/relay. Inspect for chafe points (hinges, underbody clips). Repair damaged sections and protect harness.
If wiring appears intact, test the switch/relay/BCM output. Command the lamp ON/OFF (using scan tool if available) and verify proper switching. Replace faulty control device if it provides constant battery feed.
After repair, clear codes, reconnect components and verify lamp operates normally through multiple cycles and vehicle movements. Monitor for reoccurrence and perform road/door-cycle checks as needed.

Likely causes

Chafed/pinched wiring at a moving joint (door/step)
Water intrusion or corrosion at the running board lamp connector
Failed or shorted running board lamp module
Improper splice or aftermarket accessory tied into lamp power

Fault status

⚠️ Status

Running Board Lamp Circuit Short to Battery — battery voltage detected on the running board lamp circuit when it should be switched or off. Fault set when over-voltage or over-current condition is detected on that circuit.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.0 hours