Network
generic / SAE
U0129
Lost Communication with Brake System Control Module
A control module that expects to talk to the engine ECU has stopped receiving messages. Most commonly seen by the TCM, instrument cluster, or BCM after the ECU has been disconnected, fitted with a faulty replacement, or the CAN wiring has been damaged. Engine usually will not run while this fault is active in other modules.
SystemNetwork
Typegeneric / SAE
GroupU0
Range / number1 / 29
Possible causes
- Brake module unpowered high
- CAN wiring to brake module broken medium
- Gateway module routing CAN messages incorrectly low
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Inspection / repair
- Difficulty: hard
- DIY: shop recommended
- Estimated cost: 100–2000 €
- Estimated time: 1–6 h
- Component: brake system control module
- Component: can bus wiring
- MIL / check engine light
- limp mode possible
Sources
References
sae:J2012