Code Definition

B1557 — Ignition Run/Start Circuit Short To Battery

System: Body  |  Type: Manufacturer-Specific  |  Make: Generic

About B1557

B1557 is a manufacturer-specific body diagnostic trouble code. It belongs to the B-prefix family of codes, which covers body, interior, airbag, or comfort-electronics faults.

When B1557 is stored, the module has detected a short-circuit (voltage pulled to ground or to supply) in the monitored circuit.

Scanning & clearing: Body (B) codes are often stored in the body control module, airbag module, or climate module. A basic OBD-II tool usually will not read body codes — an enhanced or OEM-level scan tool is typically required.

B1557 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

The B1557 code is set by the Body Control Module (BCM) when it detects a short to battery on the ignition run/start signal circuit. This circuit normally carries voltage only when the ignition switch is in the run or start position; a short to battery causes the BCM to read voltage on the input line at times when the key is in the off or accessory position. The fault typically indicates the run or start wire has been pinched against a B+ feed somewhere in the harness, or an internal switch fault is bridging accessory and run circuits. Symptoms can include the vehicle behaving as if the key is ...

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