U0140 Lost communication with the body control module

Lost communication with body control module (BCM)

U0140 in short

U0140 means other modules lost contact with the body control module, which runs locks, lights, keyless entry and often the start system. Wiring, connectors, power or ground, or a weak battery are the usual causes; some makers fix it with software. Get it checked soon, especially if gauges freeze or the car will not start.

The body control module handles locks, lights, wipers, keyless entry and often the immobiliser and start permission. Other modules expect regular messages from it, and when those stop they store U0140.

GM's PIT-4730A lists door locks cycling, intermittent no-start, a Service StabiliTrak message and the speedometer and tachometer freezing while driving with U0140 or U0073 on many 2006-2011 models. GM's 08-07-30-021 bulletins fix the same codes with a backed-out transmission harness terminal.

FCA reprograms the powertrain computer for U0140 on the 2015 Wrangler and Ram 2500/3500, and Ford has a message for it in the 2015-2017 F-150 front controls module.

Most likely causes

  1. Network wiring, connector or a backed-out terminal

    Common general cause
    Why it ranks here
    Network faults are usually wiring. GM fixed U0140 with a backed-out transmission harness terminal on 2007-2014 trucks.
    What would change this
    Rises with gauge flicker, lock cycling or other U-codes. Falls if bus resistance is about 60 ohms and connectors are tight.

  2. Body control module power, ground or low battery voltage

    Common general cause
    Why it ranks here
    A module without stable power drops off the network, and the body module often has many fuses and grounds.
    What would change this
    Rises if the battery is weak or the BCM does not answer a scan tool. Falls if supply is good.

  3. Software in the module that stored the code (FCA, Ford)

    Supported by vehicle data
    Why it ranks here
    FCA reprograms the powertrain computer for U0140 on the 2015 Wrangler and Ram 2500/3500, and Ford has a message for U0140 in the 2015-2017 F-150 front controls module.
    What would change this
    Rises if a dealer finds an update for your VIN.

  4. Failed body control module

    Possible — needs testing
    Why it ranks here
    Possible after wiring, power and software are ruled out.
    What would change this
    Rises if the BCM has good power, ground and bus wiring and still will not communicate.
    How to test the body control module (bcm)

What to test first

Start at step 1. Each result tells you what it means and where to go next.

  1. Scan all modules, note which ones stored U0140, and check whether the body module answers.

    Low riskTool: scan tool that reads all modules

    • IfMany modules store U0140 and the body module does not respond

      It meansCheck its power and ground.

      Go to step 2

    • IfOnly one module stores it

      It meansCheck the wiring to that module and bulletins.

      Go to step 3

  2. Test the battery and check terminals and main grounds.

    Low riskTool: battery tester

  3. Ask a dealer for bulletins or updates for U0140 on your VIN.

    Low risk

  4. Measure CAN resistance at the diagnostic connector with the key off and check the body module's power and ground pins.

    Use cautionTool: multimeter

    Warning:Do not probe yellow airbag connectors, and work with the ignition off. Let a shop do it if unsure.

Symptoms

  • Door locks cycling by themselves
  • Keyless entry, interior lights or power locks not working
  • Intermittent no-start
  • Speedometer and tachometer freezing while driving
  • Service StabiliTrak or multiple warning lights

How to fix

  1. Have the battery tested and check that terminals are clean and tight.

  2. Ask a dealer whether your VIN has an open bulletin or software update for U0140.

Parts and cost context

  • body control module:A replacement body module needs programming and sometimes key relearning. Rule out wiring and power first. Labour varies; get a quote.

Labor varies by vehicle and shop; get a quote before you approve a repair.

Compare used part prices on PartPriceGuide

On your vehicle

Chevrolet

  • 2006–2011 · Silverado 1500

    Supported by vehicle data

    GM PIT-4730A: extra diagnostics for U0140 with lock cycling, no-start and frozen gauges, across many GM models. Whether it is still current is not verified.

  • PIT-4730AStatus unverified

    Additional diagnostic information for U0140 or U0073

    2006–2011silverado-1500, tahoe, suburban, impala, equinox, traverse · issued · NHTSA 10036550

    Extra diagnostics for door locks cycling, intermittent no-start, Service StabiliTrak and frozen gauges with U0140 or U0073. Covers many Buick, Cadillac, Chevrolet, GMC, Hummer, Pontiac and Saturn models.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 08-07-30-021HStatus unverified

    Loss of high-speed GMLAN communications, intermittent no crank

    2007–2014silverado-1500, tahoe, suburban, avalanche, corvette · issued · NHTSA 10113715

    Repair for loss of GMLAN data with lost-communication codes; the earlier issue repairs a backed-out terminal in the transmission harness connector.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Ford

  • 2015–2017 · F-150

    Supported by vehicle data

    Ford SSM 46902: intermittent A/C, radio or window switches with U0140 in the front controls module. Whether it is still current is not verified.

  • SSM 46902Status unverified

    Intermittent A/C, radio or window switch control with U0140 and others

    2015–2017f-150 · issued · NHTSA 10127407

    Service message for front controls faults with these codes in the front controls interface module.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Jeep

  • 2015 · Wrangler

    Supported by vehicle data

    FCA 18-024-15 reprograms the powertrain computer for U0140; FCA 1806814 also covers U0140 on this model. Whether they are still current is not verified.

  • 18-024-15Status unverified

    Flash: U0140 lost communication with body control module

    2015wrangler · issued · NHTSA 10144838

    Reprograms the powertrain computer with updated software for U0140.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • 1806814Status unverified

    U0140 lost communication with body control module

    2015wrangler · issued · NHTSA 10232005

    FCA bulletin for U0140; the summary does not say what the repair is.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

Ram

  • 2015 · 2500

    Supported by vehicle data

    FCA 18-013-15 reprograms the powertrain computer for U0140 (also 3500). Whether it is still current is not verified.

  • 18-013-15Status unverified

    Flash: U0140 lost communication with BCM

    20152500, 3500 · issued · NHTSA 10144822

    Reprograms the powertrain computer with the latest software for U0140.

    We couldn't confirm whether this bulletin is still current, so it doesn't count as confirmation.

  • U0073A module found its data network (bus A) switched off or not working

    Shares causes Supported by vehicle data

    GM's PIT-4730A gives the same additional diagnostics for U0140 and U0073. A bus that is down cuts off the body module too.

  • U0100Lost communication with the engine or powertrain computer

    Shares causes Supported by vehicle data

    GM's GMLAN bulletin lists U0140 with U0100 and other codes from one backed-out terminal.

  • U0401A module received invalid data from the engine or powertrain computer

    Shares causes Supported by vehicle data

    Ford's 2015-2017 F-150 message lists U0140 and U0401 together in the front controls interface module.

All Module network (CAN bus) communication codes

U0140 questions

Why are my door locks clicking by themselves?

GM lists door lock cycling with U0140 when the body module loses network contact. Check the battery and wiring before replacing the module.

Sources and review

  1. GM PIT-4730A: Additional diagnostic information for U0140 or U0073 — General Motors / NHTSA ,
  2. ASE L1 study guide: Network U-codes — Open Exam Prep
  3. GM 08-07-30-021: Loss of high-speed GMLAN, intermittent no crank, DTCs U0073/U0100/U0101/U0102/U0121/U0140 — General Motors / NHTSA ,
  4. FCA 18-024-15: Flash: U0140 lost communication with body control module — FCA US LLC / NHTSA ,
  5. FCA 18-013-15: Flash: U0140 lost communication with body control module (BCM) — FCA US LLC / NHTSA ,
  6. Ford SSM 46902: 2015-2017 F-150 intermittent A/C, radio or window switch control with U0140/U0155/U0253/U0401/U0452 — Ford Motor Company / NHTSA ,
  7. FCA 1806814: U0140 lost communication with body control module — FCA US LLC / NHTSA ,
Last reviewed
Written by
Saurabh K.
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