Code
U1101
MITSUBISHI
U — Network/User
T/M CAN timeout/Not equipped
Views:
UK: 9
EN: 13
RU: 11
AI status
Completed
Completed
100%
Causes
- Faulty or disconnected Transmission Control Module (TCM)
- Broken, shorted or corroded CAN bus wiring/connectors between TCM and network
- Poor power or ground to the TCM (blown fuse, bad ground, low battery)
- Missing or non‑equipped TCM/module by design or factory option
- Failed TCM or other node pulling the bus down
- Incorrect or missing termination resistors on the CAN bus
Symptoms
- MIL/Check Engine or combination warning illuminated
- Transmission in limp/backup mode or reduced functionality
- No communication with TCM using a diagnostic scanner
- Gear selection/shift indicators missing or incorrect
- Other modules reporting lost communication or network faults
- Erratic vehicle behavior related to transmission control
What to check
- Read all stored and pending DTCs with a capable scan tool; note freeze frame and related U-codes
- Verify whether vehicle is equipped with a TCM per service documentation or vehicle option records
- Visually inspect CAN connectors and wiring near the transmission and along harness for damage, corrosion or loose pins
- Check TCM power and ground circuits (fuses, relays, continuity to ground)
- Measure CAN bus termination resistance between CAN-H and CAN-L with ignition off (approx. 60 ohms expected)
- With ignition on, measure idle voltages: CAN-H and CAN-L (approx. 2.5 V common mode; see signal_params)
Signal parameters
- Idle common-mode voltage ~2.5 V on both CAN‑H and CAN‑L (vehicle dependent)
- Dominant state voltages: CAN‑H ~3.5 V, CAN‑L ~1.5 V (approx. values)
- Differential amplitude (dominant) roughly 2.0 V
- Typical termination: two 120 Ω resistors in parallel ≈60 Ω across CAN‑H/CAN‑L
- Common CAN bus speeds: 500 kbps or 250 kbps (verify vehicle spec)
- Expected message periodicity: many control messages every 10–100 ms; a module timeout is typically several hundred ms (refer to OEM spec)
Diagnostic algorithm
- Confirm code and vehicle build: verify whether a TCM should be present for this model/trim
- Scan other modules for related U‑codes to identify affected network segments
- Perform visual inspection of transmission area harness, connectors and mating pins; repair any damage
- Check and restore TCM power and ground feeds: test fuses, relays and continuity to battery/ground
- Measure termination resistance between CAN‑H and CAN‑L (ignition off). If open or far from ≈60 Ω, investigate termination resistors or disconnected/removed module
- With an oscilloscope or CAN diagnostic tool, observe bus traffic and identify whether the TCM is transmitting. If no TCM traffic but other modules communicate, isolate wiring between last good node and TCM
- Perform wiggle test on harness/connectors while monitoring for changes in bus activity or DTCs
- Disconnect suspected aftermarket devices or splices that could load the bus and re-test
- If wiring and power/grounds are good and module remains unresponsive, consider reflashing or replacing the TCM per OEM procedure
- After repair, erase codes and perform road test/operational checks to verify communication restored and no related codes return
Likely causes
- Loose or corroded connector at the transmission module
- Blown fuse or missing power/ground to the TCM
- Damaged CAN-H or CAN-L wiring (pinched or chafed)
- Failed TCM or internal module fault
- Vehicle variant not fitted with a TCM or harness splice omitted
Fault status
Status
Transmission CAN communication timeout — no response from Transmission Control Module (TCM) or module not equipped/absent.
Repair difficulty: Medium
Diagnostic time: 0.5-3 hours
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Code
U1101
Other
U — Network/User
SCP (J1850) Invalid or Missing Data for Primary Id
Views:
UK: 18
EN: 22
RU: 23
AI status
Completed
Completed
100%
Causes
- Faulty or disconnected Transmission Control Module (TCM)
- Broken, shorted or corroded CAN bus wiring/connectors between TCM and network
- Poor power or ground to the TCM (blown fuse, bad ground, low battery)
- Missing or non‑equipped TCM/module by design or factory option
- Failed TCM or other node pulling the bus down
- Incorrect or missing termination resistors on the CAN bus
Symptoms
- MIL/Check Engine or combination warning illuminated
- Transmission in limp/backup mode or reduced functionality
- No communication with TCM using a diagnostic scanner
- Gear selection/shift indicators missing or incorrect
- Other modules reporting lost communication or network faults
- Erratic vehicle behavior related to transmission control
What to check
- Read all stored and pending DTCs with a capable scan tool; note freeze frame and related U-codes
- Verify whether vehicle is equipped with a TCM per service documentation or vehicle option records
- Visually inspect CAN connectors and wiring near the transmission and along harness for damage, corrosion or loose pins
- Check TCM power and ground circuits (fuses, relays, continuity to ground)
- Measure CAN bus termination resistance between CAN-H and CAN-L with ignition off (approx. 60 ohms expected)
- With ignition on, measure idle voltages: CAN-H and CAN-L (approx. 2.5 V common mode; see signal_params)
Signal parameters
- Idle common-mode voltage ~2.5 V on both CAN‑H and CAN‑L (vehicle dependent)
- Dominant state voltages: CAN‑H ~3.5 V, CAN‑L ~1.5 V (approx. values)
- Differential amplitude (dominant) roughly 2.0 V
- Typical termination: two 120 Ω resistors in parallel ≈60 Ω across CAN‑H/CAN‑L
- Common CAN bus speeds: 500 kbps or 250 kbps (verify vehicle spec)
- Expected message periodicity: many control messages every 10–100 ms; a module timeout is typically several hundred ms (refer to OEM spec)
Diagnostic algorithm
- Confirm code and vehicle build: verify whether a TCM should be present for this model/trim
- Scan other modules for related U‑codes to identify affected network segments
- Perform visual inspection of transmission area harness, connectors and mating pins; repair any damage
- Check and restore TCM power and ground feeds: test fuses, relays and continuity to battery/ground
- Measure termination resistance between CAN‑H and CAN‑L (ignition off). If open or far from ≈60 Ω, investigate termination resistors or disconnected/removed module
- With an oscilloscope or CAN diagnostic tool, observe bus traffic and identify whether the TCM is transmitting. If no TCM traffic but other modules communicate, isolate wiring between last good node and TCM
- Perform wiggle test on harness/connectors while monitoring for changes in bus activity or DTCs
- Disconnect suspected aftermarket devices or splices that could load the bus and re-test
- If wiring and power/grounds are good and module remains unresponsive, consider reflashing or replacing the TCM per OEM procedure
- After repair, erase codes and perform road test/operational checks to verify communication restored and no related codes return
Likely causes
- Loose or corroded connector at the transmission module
- Blown fuse or missing power/ground to the TCM
- Damaged CAN-H or CAN-L wiring (pinched or chafed)
- Failed TCM or internal module fault
- Vehicle variant not fitted with a TCM or harness splice omitted
Fault status
Status
Transmission CAN communication timeout — no response from Transmission Control Module (TCM) or module not equipped/absent.
Repair difficulty: Medium
Diagnostic time: 0.5-3 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
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👎 Dislike
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Send to email