B1678

Code

Other B — Body

Alarm Panic Input Circuit Open

Brand: Other

Type: B — Body

Views: UK: 22 EN: 37 RU: 28

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Read and record all stored codes and freeze frame data with a scan tool
Review vehicle wiring diagram to locate panic switch, harness routing, connector pinouts, and related fuses/grounds
Visually inspect switch, harness, and connectors for damage, corrosion, or disconnected plugs
Check related fuses and power/ground circuits
Backprobe the panic input at the module and switch while operating the switch or pressing key fob
Perform continuity check between switch and module connector pins with ignition off

Circuit type: momentary switch input (can be pulled to ground or to battery depending on design)
Inactive (open) state: typically near battery voltage (approx. 11–14 V) if pulled‑up, or near 0 V if pulled‑down — consult vehicle wiring diagram
Active (closed) state: opposite of inactive (transition to near 0 V if switch grounds the circuit, or to battery voltage if switch supplies 12 V)
Resistance across a working momentary switch when closed: near 0 ohms; when open: high (OL)
Typical pull‑up/pull‑down resistor values internal to module: commonly kiloohm range (e.g., 10 kΩ–47 kΩ), vary by manufacturer

Verify the code with a scan tool and note freeze frame and related codes. Do not clear codes yet.
Obtain the wiring diagram for the alarm/panic input to identify connectors, pin numbers, fuses and related grounds.
Visually inspect the panic switch assembly, connectors, and harness for damage, corrosion, water intrusion, or aftermarket splices. Repair obvious issues.
Check fuses and power/ground circuits that service the alarm/panic system; repair any blown fuses or bad grounds.
Backprobe the panic input at the body/comms module with the ignition on and monitor voltage while operating the panic switch or pressing the key fob panic. Compare behavior to expected signal (see Signal Params).
If the signal is absent, disconnect the switch connector and measure continuity from the switch connector to the module connector to locate an open. Repair any open or high-resistance wiring.
Test the panic switch directly: measure resistance across switch terminals while pressing; replace switch if it fails to change state.
Inspect and test for unintended open caused by aftermarket alarm or remote start. Temporarily disconnect aftermarket unit to isolate fault.
If wiring and switch test good but module input never changes, consider module input failure. Verify by checking other inputs on the module or substitute a known-good module if available.
After repairs, clear codes, operate the panic function multiple times, and road/test to confirm the fault does not return.