U3006: Alimentation d'entrée A du calculateur — circuit ouvert
Que faire
Have the battery and its connections tested before anything else is touched — including the battery terminals themselves, cleaned and retightened.
That sounds too simple for a code like this, and it is still the right first step: a battery weak enough to sag while cranking, or a terminal corroded under a clamp that looks perfectly tight, produces this entire family of faults exactly. It is the cheapest thing to rule out and the most common cause by a distance.
If the car has a page of unrelated warning lights, expect most of them to clear when this is fixed. A module with a poor supply reports nonsense about everything it watches, so one bad connection can light up half the dashboard.
Mention two things: whether the car has had a flat battery or a jump start recently, and whether any bodywork or accessory fitting has been done. A body shop that bolts an earth strap onto fresh paint makes a connection that looks perfect and conducts badly — and that is a classic cause.
Ce que signifie ce code
The control module's input power circuit A is open or has lost its supply.
This range is different from every other network family, and the difference decides how it should be diagnosed.
U01xx and U02xx say a module went silent. U04xx and U05xx say a module is talking nonsense about something it watches. This range says a module is reporting a problem with its own foundations — its supply, its earth, or the ignition state that tells it whether the car is even meant to be awake.
Which makes these codes upstream of almost everything else. A module with a marginal earth does not fail cleanly; it reports implausible values about every sensor it reads, sets codes in unrelated systems, and drops off the bus intermittently. A scan tool showing thirty codes across five systems very often has one of these underneath it.
So read this family first and fix it first. Clearing a page of downstream codes before the supply fault is repaired produces a page of downstream codes again by the end of the week.
And start with the battery, genuinely. Not as a formality — a twelve-volt battery weak enough to sag during cranking, or a terminal with corrosion under a clamp that looks tight, reproduces this entire family exactly. It is the cheapest thing to eliminate and by some distance the most common cause.
A module with more than one power feed has them for a reason, and the letter says which one has gone.
Separate feeds do separate jobs. One typically keeps memory and wake-up logic alive permanently; another comes on with the ignition; a third may power output drivers that switch real current. A module can therefore be alive and communicating while a circuit it needs is missing, which is exactly what this code describes and why the module is able to report it at all.
Which explains a symptom pattern that otherwise makes no sense: a module that answers a scan tool perfectly but cannot operate anything. The processor has power; the output stage does not.
Fuses first, and check the right one. A module with several feeds has several fuses, frequently in different boxes — one under the bonnet, one in the cabin — and the missing one is by definition not the one that is obviously working. A blown fuse is also a symptom rather than a cause: something made it blow, and replacing it without asking why usually means replacing it again.
The letter is the manufacturer's, not the standard's. Only the vehicle's own wiring documentation says which physical feed is A, B, C or D.
Causes probables
Commencez ici
- Tension du système basse · facile
- Connexion de masse corrodée · modérée
- Fusible grillé ou alimentation hors service · facile
- Alimentation ou masse du calculateur hors service · modérée
- Connecteur corrodé ou mal enclenché · facile
Moins fréquent
- Faisceau de câblage endommagé · modérée
Symptômes
Composants concernés
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