Code
B1600
Other
B — Body
PATS Ignition Key Transponder Signal Is Not Received
AI status
Completed
Completed
100%
Causes
- Key transponder absent or damaged
- Ignition cylinder/wiring fault between lock and theft-deterrent module
- Theft-deterrent/module (PATS/BCM/ICM) failure or programming loss
- Antenna/coils that read the transponder are faulty or misaligned
- Intermittent connector or power/ground problem to the theft‑deterrent module
- Interference from aftermarket electronics or radio-frequency sources
Symptoms
- Engine will not crank or starter is disabled
- Starter cranks but engine does not start (fuel/ignition disabled)
- Security/immobilizer lamp illuminated or flashing on dash
- Intermittent no-start that clears when using another key
- No response from remote functions on non-related systems (in some cases)
What to check
- Use a scan tool to read B1600 and any related security data or freeze frames
- Verify vehicle security/immobilizer lamp state during key turn to ON and crank positions
- Try all known good keys (including spare) to see if any key is recognized
- Inspect ignition lock cylinder and antenna ring for visible damage or loose/missing parts
- Check power and ground at the theft‑deterrent module and connectors for corrosion or looseness
- Look for recent work, battery disconnects, or aftermarket installs that coincide with fault appearance
Signal parameters
- Key transponder responds on a low‑frequency RFID band (typical LF reader ~125 kHz; specific frequency is manufacturer‑dependent)
- Transponder signal contains an encoded digital ID; reader expects a valid programmed ID
- Reader/antenna is passive; power for the immobilizer module is typically vehicle 12 V supply and ground
- Communication between immobilizer module and ECM/BCM is via vehicle bus or dedicated serial link (check for normal bus messages)
Diagnostic algorithm
- Retrieve all security-related codes with a capable scan tool; note freeze frame and time stamps.
- Verify symptom: turn ignition to ON and observe security lamp behavior and any CAN/bus messages indicating key not found.
- Try known good/spare keys. If a spare key works, suspect primary key transponder failure or programming issue.
- Visually inspect the ignition cylinder/antenna ring assembly for damage and check connectors at the antenna and theft‑deterrent module for corrosion, bent pins, or loose wires.
- With scan tool, monitor the immobilizer/BCM for the transponder ID read event while a key is turned. If no ID event, test antenna ring continuity and wiring to module per service manual.
- Check module power/ground and communication lines (CAN or serial) for proper voltages and message traffic; repair any wiring faults.
- If antenna and wiring are good but no key ID is received, try reprogramming or re-learning keys per manufacturer procedure — ensure tool supports PATS.
- If reprogramming fails or module shows internal faults, replace the theft‑deterrent module or antenna assembly following dealer/ OEM instructions and reprogram keys.
- After repairs, clear codes and verify that all keys are learned and that the vehicle starts reliably; recheck for stored security codes.
Likely causes
- Key transponder chip failed or key is not the programmed spare
- Damaged antenna ring or wiring at the ignition switch
- Corroded/loose connectors at PATS/BCM or ignition switch harness
- Theft-deterrent module lost its learned key IDs after battery disconnect or replacement
- Aftermarket alarm/remote starter interfering with transponder communication
Fault status
Status
Transponder key ID not received by theft‑deterrent module — immobilizer active; vehicle may not start until valid key is recognized.
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
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