Code
P1197
FORD
P — Powertrain
Key Off Voltage Low
Views:
UK: 28
EN: 36
RU: 35
AI status
Completed
Completed
100%
Causes
- Weak or discharged battery
- Poor battery cable or terminal connection (corrosion, loose)
- High parasitic battery drain while key off (aftermarket device, short)
- Open/short or high-resistance in key‑off/standby sense wiring or connector
- Blown fuse or bad fusible link feeding the sensing circuit
- Faulty body control module (BCM) / powertrain control module (PCM) or internal sensor
Symptoms
- Battery warning lamp or message (may not always appear)
- Battery voltage low after vehicle sits; may fail to crank after long park
- Accessory or alarm behaving erratically while vehicle is off
- DTC P1197 stored in control module; may be accompanied by other voltage/charging codes
What to check
- Read and record freeze frame and related codes with a scan tool
- Measure and record actual battery voltage at battery posts with ignition off
- Measure voltage at the BCM/PCM key‑off sense pin and compare to battery voltage
- Inspect battery terminals, cable ends and chassis engine grounds for corrosion, tightness and damage
- Check for blown fuses or fusible links related to the key‑off/standby circuit
- Perform parasitic draw test (ammeter in series) to identify abnormal current drain while vehicle is asleep
Signal parameters
- Nominal battery voltage with key off: ~12.4–12.8 V (fully charged)
- Typical trigger threshold: manufacturer-specific — P1197 set when key‑off sense falls well below expected level (often below ~9–10 V)
- Expected behavior: key‑off sense should track battery voltage with minimal voltage drop; large voltage drop or near 0 V indicates open/short to ground
Diagnostic algorithm
- Verify conditions and recreate fault: confirm ignition off and vehicle asleep per manufacturer procedure
- Scan for DTCs and freeze frame data; note any related voltage/charging codes
- Visually inspect battery, cables, clamps and ground straps; clean and tighten as needed
- Measure battery voltage at posts. If low (
- Measure voltage at the BCM/PCM key‑off sense terminal with respect to chassis ground; compare to battery post voltage
- If sensor voltage is low while battery is good, inspect wiring from battery to module for continuity, shorts to ground, damaged insulation, and connector corrosion; repair as required
- Perform parasitic current draw test to identify excessive drain; isolate circuits by removing fuses to find culprit circuit
- Recheck after repairs, clear codes, and monitor voltage and readiness of code to return; if wiring and battery are OK and code returns, consider module fault and follow module replacement/repair procedure per Ford service information
Likely causes
- Weak or partially discharged battery
- Corroded/loose battery terminals or ground connections
- High parasitic draw from aftermarket device or short to ground
- Damaged or corroded connector/wiring at the BCM/PCM key‑off sense pin
Fault status
Status
PCM/BCM detected key‑off/standby circuit voltage below the expected threshold while ignition was off; code stored to indicate low key‑off voltage condition.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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