Code
P1404
FIAT
P — Powertrain
TL4226 circuit fault
Views:
UK: 2
EN: 8
RU: 5
AI status
Completed
Completed
100%
Causes
- Open circuit in TL4226 wiring (broken wire, disconnected connector)
- Short to battery voltage or short to ground in the TL4226 circuit
- Corroded, bent or pushed‑out connector pins at the TL4226 or ECM connector
- Failed TL4226 component (sensor/actuator)
- Blown fuse, faulty relay or poor power supply to the circuit
- Intermittent wiring fault due to chafing or heat damage
Symptoms
- Malfunction indicator lamp (MIL) illuminated
- One or more related systems operating incorrectly (reduced performance, drivability issues)
- Possible rough idle or hesitation depending on function of TL4226
- Fault may be intermittent (appears/disappears with vibration or temperature)
- Failed emissions test or stored readiness code
What to check
- Read and record freeze frame and all stored/related Trouble Codes with a capable scan tool
- Inspect TL4226 connector and wiring visually for corrosion, damage, loose pins or water intrusion
- Check fuses and relays supplying the TL4226 circuit
- Backprobe the TL4226 connector to measure reference voltage, switched power and ground with ignition ON and engine OFF/ON as applicable
- Perform continuity and resistance checks on wiring between TL4226 and the ECM, and to ground
- Wiggle test wiring while monitoring live data or fault status to reproduce intermittent faults
Signal parameters
- Reference/signal voltage typically uses a control/reference circuit — compare to factory spec (common values: reference ~5 V, switched supply ~12 V when active)
- Ground continuity:
- Signal behavior: may be a steady voltage, variable voltage or pulsed/duty signal depending on TL4226 function — consult factory data for waveform/duty/frequency
- Watch for voltage spikes, high resistance in supply or signal lines, and intermittent loss of signal
Diagnostic algorithm
- Verify code P1404 with a scan tool and note freeze frame data and related codes.
- Visually inspect the TL4226 connector, pins and harness for damage, corrosion or contamination. Repair or replace damaged connector/cable as needed.
- Check fuses/relays that feed the TL4226 circuit; replace any faulty components.
- Backprobe the TL4226 connector: verify reference voltage, switched power and a good ground with a digital multimeter. Compare readings to factory values.
- Perform continuity/resistance tests from the TL4226 connector to the ECM connector and to chassis ground. Repair any open or high‑resistance wiring.
- If wiring and power/grounds are good, bench test or substitute a known‑good TL4226 component if available.
- Clear the code, perform a road test and recheck for reappearance of the code. If fault returns and wiring/component checks are OK, consider ECM diagnosis.
- Document repairs and re‑verify proper operation and absence of stored faults.
Likely causes
- Damaged or chafed harness near engine or heat sources
- Corroded or contaminated connector at TL4226
- Failed TL4226 unit after exposure to moisture/heat
- Loose or corroded ground at engine/chassis
- Blown inline fuse or faulty power feed/relay
Fault status
Status
P1404 — TL4226 circuit fault. The ECU detected an electrical fault (open, short, intermittent or supply/ground problem) in the TL4226 circuit. Investigation of wiring, connectors, fuses/relays and the TL4226 unit is required.
Repair difficulty: Medium
Diagnostic time: 0.5–2.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email