U0553 Moderate Generic / SAE

U0553: Invalid Data Received From Lighting Control Module - Rear B

Network and Communication Invalid Data Received (continued)

What to do

Get somebody to stand behind the car while you press the brake pedal, put the indicators on, and select reverse. Do it today.

This code covers the module that runs the rear lights, and its failure has an awkward property: the car's own bulb-failure warning stops being reliable at the same time the lights themselves might be. You cannot trust the dashboard to tell you, so you have to look.

Brake lights are the ones that matter — a car without them gets rear-ended, and there is no warning from inside.

If a towbar or trailer electrics kit has been fitted, mention it. A badly wired kit feeding current back into the light circuits is a common cause of this exact code, and it is a wiring correction rather than a module replacement.

Check the lamp units for water inside, too — a fogged or part-filled rear lamp is a failed seal, and the corrosion that follows is the usual culprit.

What this code means

Lighting control module - rear B is broadcasting data that cannot be accepted as true. See U0400 for what an invalid-data code is and why the module it names is usually the messenger rather than the culprit.

The letter is the part of this code that actually tells you something, and it is worth reading carefully.

The standard letters each instance of a repeated module — one per door, one per seat, one per window — so the letter narrows a whole-vehicle fault to one corner of the car before anybody lifts a trim panel. What the letter does not do is say which corner, because the mapping from letter to physical position is the manufacturer's to choose and it is not consistent between makes.

Only the vehicle's own documentation resolves the letter to a location. Guessing costs a stripped door card and proves nothing.

Two practical consequences. If several letters in the same family are stored together, the fault is upstream of all of them — a shared supply, a shared earth, or the bus itself — and chasing one door is wasted work. And if exactly one letter is stored, you have been handed the most valuable diagnostic fact available: the other instances are working, so everything they share is proven good.

A rear lighting module is the one component in this range whose failure is both dangerous and completely invisible from the driver's seat.

Rear lamps are increasingly driven by a module rather than by a switch and a fuse, because LED clusters need current control and because the car wants to know when a lamp has failed. The module reports lamp states and measured loads back to the network.

Which produces the specific hazard: when that data cannot be trusted, the car's own bulb-failure warning becomes unreliable at the same moment the lamps themselves may be misbehaving. You lose the fault and the thing that would have told you about the fault, together.

So the instruction is to look rather than to rely on the dashboard. Brake lights especially: a car without brake lights is rear-ended, and nothing inside the car will necessarily say so.

The physical causes sit at the back of the car and are the wet ones — a lamp unit whose seal has failed and filled with water, corroded bulb-holder contacts, a tailgate loom broken at the flex point, a towbar electrics kit spliced in badly. Towbar wiring is worth naming: a poorly installed kit that back-feeds the lighting circuits produces exactly this, and it is common.

Likely causes

Start here

Corroded or loose connector · easy
Damaged data bus wiring · moderate
Water ingress into connector · moderate
Poor wiring splice in an aftermarket installation · moderate

Less common

Module not coded to the vehicle · specialist
Water ingress into module · moderate
Damaged wiring harness · 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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