U0144: Lost Communication With Body Control Module D
What to do
Before driving anywhere, have somebody stand behind the car while you use the brakes, the indicators, the hazards, the lights and reverse gear.
On most cars this code names the computer at the back, which runs the rear lights, the rear wiper, the heated rear screen and the boot lock. The reason to check is that you cannot see any of it from the driver's seat, and driving with no brake lights is genuinely dangerous rather than merely inconvenient. In most places it is also illegal.
Then look under the boot floor, where the spare wheel lives. These modules sit in the wettest part of the car, and standing water there — from an aged tailgate seal, a blocked drain channel, or a rear light gasket that has gone hard — is the commonest cause of this fault by a wide margin. Finding water is more useful than any test, and drying and sealing it is the actual repair.
One more free check if the fault comes and goes: open and close the tailgate slowly and see whether anything changes. The wiring runs through the hinge and flexes every time, and it breaks inside insulation that still looks perfect.
Otherwise, ask for the fuses and relays nearest the dead area to be checked first.
What this code means
A body control module has stopped being heard from. See U0141 for the supply argument and U0443 for what the letters mean.
On most vehicles carrying this many body modules, D is at the back, and that changes both what stops working and what should be checked.
A rear zone module typically operates the light clusters, the number plate lamps, the rear wiper and washer, the heated rear screen, the boot or tailgate lock and, on a powered tailgate, its motor and pinch protection. So a single silent module takes out a set of things that look unrelated and are all at the same end of the vehicle.
The safety point comes first and it is the reason this page is not merely inconvenient. Every light this module operates is invisible from the driver's seat. A headlight that fails announces itself on the first dark road; brake lights that have stopped announce themselves to nobody. Have somebody stand behind the vehicle and work through the brake pedal, the indicators, the hazards, the lights and reverse gear before driving anywhere — it takes a minute and it is the whole of the urgency here.
Then the diagnosis. The rear of a vehicle is its wettest structural region: tailgate seals age, drain channels fill with leaf litter, and a light cluster gasket that has hardened lets water into the boot floor rather than outside it. Lift the boot floor and look under the spare wheel — standing water there explains this code and a great deal else.
And the harness through a tailgate hinge flexes exactly like a door boot and fails the same way, with the same free test: does it change as the tailgate is moved.
Likely causes
Start here
- Water ingress into module · moderate
- Broken wire in the door harness boot · moderate
- Corroded or loose connector · easy
- Blown fuse or failed supply · easy
Less common
- Damaged wiring harness · moderate
- Damaged data bus wiring · moderate
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
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