Code
B1493
ALFA ROMEO
B — Body
Ignition cylinder sensor short to positive
Views:
UK: 3
EN: 3
RU: 3
AI status
Completed
Completed
100%
Causes
- Short circuit between ignition cylinder sensor signal wire and battery positive (B+).
- Corroded/damaged connector or wiring harness causing a high-resistance/short path to B+.
- Faulty ignition cylinder sensor or key switch with internal short to battery.
- Aftermarket alarm/immobilizer or recent electrical work incorrectly wired into the ignition circuit.
- Faulty control module input (internal short in ECU/Body Control Module).
Symptoms
- No crank or no-start condition when turning key (intermittent or permanent).
- Immobilizer or key warning light on the dash.
- Ignition positions (ACC/ON/START) behave incorrectly or unpredictably.
- Blown fuse(s) on ignition feed or related circuits.
- Stored DTC(s) related to ignition/immobilizer and power supply.
What to check
- Read and record all stored DTCs and freeze frame data; clear codes and attempt to reproduce.
- Visually inspect ignition cylinder connector and wiring for damage, corrosion, pin push-out, or aftermarket splices.
- Check fuses and relays for the ignition/immobilizer circuits.
- Backprobe the sensor signal with a multimeter while operating the key through positions.
- Disconnect the ignition cylinder sensor connector and check whether the code returns (helps isolate sensor vs. wiring/module).
- If available, use a scope to observe the signal under key operated conditions to identify constant B+ or shorted pulses.
Signal parameters
- Expected with key OFF: signal ~0 V or open circuit (depends on design).
- Expected with ACC/ON/START: signal usually close to battery voltage (~9–14 V) for switched 12V type, or a defined logic voltage (approximately 0–5 V) for low-voltage sensors — consult vehicle wiring diagram.
- Fault condition: persistent >9 V on a low-voltage input or signal stuck at battery voltage when it should be low indicates short to positive.
- Fault threshold: input measured near battery voltage when it should be low, or continuity between signal pin and B+ with ignition off.
Diagnostic algorithm
- Record codes and symptoms. Disconnect battery negative if performing connector repairs.
- Visually inspect the ignition cylinder/switch connector, wiring harness runs (through steering column), and any nearby components for abrasion, pinch points, or aftermarket taps.
- With ignition OFF, measure DC voltage between the ignition cylinder signal pin and chassis ground. Note voltage and compare to expected (0 V or battery depending on design).
- Check continuity between the signal pin and battery positive (B+) with ignition OFF. An unexpected continuity (low ohms) suggests a short.
- Disconnect the ignition cylinder sensor connector and re-test continuity from the harness side to B+. If continuity remains, wiring harness or splice is shorted; if it disappears, suspect the sensor.
- If wiring shows no short, reconnect sensor and monitor the signal while an assistant turns the key through positions. Use a scope if available to see transitions and spikes.
- Inspect and disconnect any aftermarket devices (alarms, immobilizers, bypass modules) that tap the ignition feed; retest after removal.
- If harness and sensor check good, check the receiving ECU/BCM input for internal short by unplugging the module (if possible) and rechecking continuity to B+. Refer to manufacturer service manual before module removal.
- Repair damaged wiring (replace sections, repair connectors) or replace faulty ignition cylinder sensor. After repair, clear codes and verify correct operation and that the DTC does not return.
- If all external tests pass and the fault persists, consult dealer-level wiring diagrams and consider module repair/replacement as a last step.
Likely causes
- Chafed wiring harness where the signal wire contacts a positive feed or fused ignition feed.
- Pin pushed out or bent in the sensor/ECU connector making contact with B+ terminal.
- Moisture intrusion causing conductive path between signal and positive circuits.
- Ignition cylinder sensor failed internally (short to positive inside sensor).
- Improperly installed alarm/starter cut relay tied to the ignition signal.
Fault status
Status
Ignition cylinder sensor circuit short to positive detected — the control module reports an over-voltage on the ignition cylinder/ignition switch input.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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Code
B1493
FIAT
B — Body
Ignition cylinder sensor short to positive
Views:
UK: 2
EN: 3
RU: 2
AI status
Completed
Completed
100%
Causes
- Short circuit between ignition cylinder sensor signal wire and battery positive (B+).
- Corroded/damaged connector or wiring harness causing a high-resistance/short path to B+.
- Faulty ignition cylinder sensor or key switch with internal short to battery.
- Aftermarket alarm/immobilizer or recent electrical work incorrectly wired into the ignition circuit.
- Faulty control module input (internal short in ECU/Body Control Module).
Symptoms
- No crank or no-start condition when turning key (intermittent or permanent).
- Immobilizer or key warning light on the dash.
- Ignition positions (ACC/ON/START) behave incorrectly or unpredictably.
- Blown fuse(s) on ignition feed or related circuits.
- Stored DTC(s) related to ignition/immobilizer and power supply.
What to check
- Read and record all stored DTCs and freeze frame data; clear codes and attempt to reproduce.
- Visually inspect ignition cylinder connector and wiring for damage, corrosion, pin push-out, or aftermarket splices.
- Check fuses and relays for the ignition/immobilizer circuits.
- Backprobe the sensor signal with a multimeter while operating the key through positions.
- Disconnect the ignition cylinder sensor connector and check whether the code returns (helps isolate sensor vs. wiring/module).
- If available, use a scope to observe the signal under key operated conditions to identify constant B+ or shorted pulses.
Signal parameters
- Expected with key OFF: signal ~0 V or open circuit (depends on design).
- Expected with ACC/ON/START: signal usually close to battery voltage (~9–14 V) for switched 12V type, or a defined logic voltage (approximately 0–5 V) for low-voltage sensors — consult vehicle wiring diagram.
- Fault condition: persistent >9 V on a low-voltage input or signal stuck at battery voltage when it should be low indicates short to positive.
- Fault threshold: input measured near battery voltage when it should be low, or continuity between signal pin and B+ with ignition off.
Diagnostic algorithm
- Record codes and symptoms. Disconnect battery negative if performing connector repairs.
- Visually inspect the ignition cylinder/switch connector, wiring harness runs (through steering column), and any nearby components for abrasion, pinch points, or aftermarket taps.
- With ignition OFF, measure DC voltage between the ignition cylinder signal pin and chassis ground. Note voltage and compare to expected (0 V or battery depending on design).
- Check continuity between the signal pin and battery positive (B+) with ignition OFF. An unexpected continuity (low ohms) suggests a short.
- Disconnect the ignition cylinder sensor connector and re-test continuity from the harness side to B+. If continuity remains, wiring harness or splice is shorted; if it disappears, suspect the sensor.
- If wiring shows no short, reconnect sensor and monitor the signal while an assistant turns the key through positions. Use a scope if available to see transitions and spikes.
- Inspect and disconnect any aftermarket devices (alarms, immobilizers, bypass modules) that tap the ignition feed; retest after removal.
- If harness and sensor check good, check the receiving ECU/BCM input for internal short by unplugging the module (if possible) and rechecking continuity to B+. Refer to manufacturer service manual before module removal.
- Repair damaged wiring (replace sections, repair connectors) or replace faulty ignition cylinder sensor. After repair, clear codes and verify correct operation and that the DTC does not return.
- If all external tests pass and the fault persists, consult dealer-level wiring diagrams and consider module repair/replacement as a last step.
Likely causes
- Chafed wiring harness where the signal wire contacts a positive feed or fused ignition feed.
- Pin pushed out or bent in the sensor/ECU connector making contact with B+ terminal.
- Moisture intrusion causing conductive path between signal and positive circuits.
- Ignition cylinder sensor failed internally (short to positive inside sensor).
- Improperly installed alarm/starter cut relay tied to the ignition signal.
Fault status
Status
Ignition cylinder sensor circuit short to positive detected — the control module reports an over-voltage on the ignition cylinder/ignition switch input.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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Code
B1493
MITSUBISHI
B — Body
F ABG(2)PS squib short to BATT.
Views:
UK: 7
EN: 8
RU: 8
AI status
Completed
Completed
100%
Causes
- Short circuit between ignition cylinder sensor signal wire and battery positive (B+).
- Corroded/damaged connector or wiring harness causing a high-resistance/short path to B+.
- Faulty ignition cylinder sensor or key switch with internal short to battery.
- Aftermarket alarm/immobilizer or recent electrical work incorrectly wired into the ignition circuit.
- Faulty control module input (internal short in ECU/Body Control Module).
Symptoms
- No crank or no-start condition when turning key (intermittent or permanent).
- Immobilizer or key warning light on the dash.
- Ignition positions (ACC/ON/START) behave incorrectly or unpredictably.
- Blown fuse(s) on ignition feed or related circuits.
- Stored DTC(s) related to ignition/immobilizer and power supply.
What to check
- Read and record all stored DTCs and freeze frame data; clear codes and attempt to reproduce.
- Visually inspect ignition cylinder connector and wiring for damage, corrosion, pin push-out, or aftermarket splices.
- Check fuses and relays for the ignition/immobilizer circuits.
- Backprobe the sensor signal with a multimeter while operating the key through positions.
- Disconnect the ignition cylinder sensor connector and check whether the code returns (helps isolate sensor vs. wiring/module).
- If available, use a scope to observe the signal under key operated conditions to identify constant B+ or shorted pulses.
Signal parameters
- Expected with key OFF: signal ~0 V or open circuit (depends on design).
- Expected with ACC/ON/START: signal usually close to battery voltage (~9–14 V) for switched 12V type, or a defined logic voltage (approximately 0–5 V) for low-voltage sensors — consult vehicle wiring diagram.
- Fault condition: persistent >9 V on a low-voltage input or signal stuck at battery voltage when it should be low indicates short to positive.
- Fault threshold: input measured near battery voltage when it should be low, or continuity between signal pin and B+ with ignition off.
Diagnostic algorithm
- Record codes and symptoms. Disconnect battery negative if performing connector repairs.
- Visually inspect the ignition cylinder/switch connector, wiring harness runs (through steering column), and any nearby components for abrasion, pinch points, or aftermarket taps.
- With ignition OFF, measure DC voltage between the ignition cylinder signal pin and chassis ground. Note voltage and compare to expected (0 V or battery depending on design).
- Check continuity between the signal pin and battery positive (B+) with ignition OFF. An unexpected continuity (low ohms) suggests a short.
- Disconnect the ignition cylinder sensor connector and re-test continuity from the harness side to B+. If continuity remains, wiring harness or splice is shorted; if it disappears, suspect the sensor.
- If wiring shows no short, reconnect sensor and monitor the signal while an assistant turns the key through positions. Use a scope if available to see transitions and spikes.
- Inspect and disconnect any aftermarket devices (alarms, immobilizers, bypass modules) that tap the ignition feed; retest after removal.
- If harness and sensor check good, check the receiving ECU/BCM input for internal short by unplugging the module (if possible) and rechecking continuity to B+. Refer to manufacturer service manual before module removal.
- Repair damaged wiring (replace sections, repair connectors) or replace faulty ignition cylinder sensor. After repair, clear codes and verify correct operation and that the DTC does not return.
- If all external tests pass and the fault persists, consult dealer-level wiring diagrams and consider module repair/replacement as a last step.
Likely causes
- Chafed wiring harness where the signal wire contacts a positive feed or fused ignition feed.
- Pin pushed out or bent in the sensor/ECU connector making contact with B+ terminal.
- Moisture intrusion causing conductive path between signal and positive circuits.
- Ignition cylinder sensor failed internally (short to positive inside sensor).
- Improperly installed alarm/starter cut relay tied to the ignition signal.
Fault status
Status
Ignition cylinder sensor circuit short to positive detected — the control module reports an over-voltage on the ignition cylinder/ignition switch input.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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Code
B1493
Other
B — Body
Ignition Cylinder Sensor Battery Short
Views:
UK: 12
EN: 18
RU: 19
AI status
Completed
Completed
100%
Causes
- Short circuit between ignition cylinder sensor signal wire and battery positive (B+).
- Corroded/damaged connector or wiring harness causing a high-resistance/short path to B+.
- Faulty ignition cylinder sensor or key switch with internal short to battery.
- Aftermarket alarm/immobilizer or recent electrical work incorrectly wired into the ignition circuit.
- Faulty control module input (internal short in ECU/Body Control Module).
Symptoms
- No crank or no-start condition when turning key (intermittent or permanent).
- Immobilizer or key warning light on the dash.
- Ignition positions (ACC/ON/START) behave incorrectly or unpredictably.
- Blown fuse(s) on ignition feed or related circuits.
- Stored DTC(s) related to ignition/immobilizer and power supply.
What to check
- Read and record all stored DTCs and freeze frame data; clear codes and attempt to reproduce.
- Visually inspect ignition cylinder connector and wiring for damage, corrosion, pin push-out, or aftermarket splices.
- Check fuses and relays for the ignition/immobilizer circuits.
- Backprobe the sensor signal with a multimeter while operating the key through positions.
- Disconnect the ignition cylinder sensor connector and check whether the code returns (helps isolate sensor vs. wiring/module).
- If available, use a scope to observe the signal under key operated conditions to identify constant B+ or shorted pulses.
Signal parameters
- Expected with key OFF: signal ~0 V or open circuit (depends on design).
- Expected with ACC/ON/START: signal usually close to battery voltage (~9–14 V) for switched 12V type, or a defined logic voltage (approximately 0–5 V) for low-voltage sensors — consult vehicle wiring diagram.
- Fault condition: persistent >9 V on a low-voltage input or signal stuck at battery voltage when it should be low indicates short to positive.
- Fault threshold: input measured near battery voltage when it should be low, or continuity between signal pin and B+ with ignition off.
Diagnostic algorithm
- Record codes and symptoms. Disconnect battery negative if performing connector repairs.
- Visually inspect the ignition cylinder/switch connector, wiring harness runs (through steering column), and any nearby components for abrasion, pinch points, or aftermarket taps.
- With ignition OFF, measure DC voltage between the ignition cylinder signal pin and chassis ground. Note voltage and compare to expected (0 V or battery depending on design).
- Check continuity between the signal pin and battery positive (B+) with ignition OFF. An unexpected continuity (low ohms) suggests a short.
- Disconnect the ignition cylinder sensor connector and re-test continuity from the harness side to B+. If continuity remains, wiring harness or splice is shorted; if it disappears, suspect the sensor.
- If wiring shows no short, reconnect sensor and monitor the signal while an assistant turns the key through positions. Use a scope if available to see transitions and spikes.
- Inspect and disconnect any aftermarket devices (alarms, immobilizers, bypass modules) that tap the ignition feed; retest after removal.
- If harness and sensor check good, check the receiving ECU/BCM input for internal short by unplugging the module (if possible) and rechecking continuity to B+. Refer to manufacturer service manual before module removal.
- Repair damaged wiring (replace sections, repair connectors) or replace faulty ignition cylinder sensor. After repair, clear codes and verify correct operation and that the DTC does not return.
- If all external tests pass and the fault persists, consult dealer-level wiring diagrams and consider module repair/replacement as a last step.
Likely causes
- Chafed wiring harness where the signal wire contacts a positive feed or fused ignition feed.
- Pin pushed out or bent in the sensor/ECU connector making contact with B+ terminal.
- Moisture intrusion causing conductive path between signal and positive circuits.
- Ignition cylinder sensor failed internally (short to positive inside sensor).
- Improperly installed alarm/starter cut relay tied to the ignition signal.
Fault status
Status
Ignition cylinder sensor circuit short to positive detected — the control module reports an over-voltage on the ignition cylinder/ignition switch input.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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