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[Doctor Gollum]

Apparently needs an alternator.

However car starts runs and drives without too much issue... Battery light intermittent.

Couple of questions...

1. Does the alternator actually need to be coded to the car?
2. Yes or No to 1, can the regulator be replaced without too much drama and are they available?

Any alternative likely culprits?

[Mr Skrunts]

Does the alternator actually need to be coded to the car?

Why would an alternator need to be coded to a car?

I asked Google. Without the car details

No, a car's alternator typically does not need to be coded to the car, unlike a replacement battery which often requires registration to the car's computer system. Coding an alternator is not a standard procedure; however, some modern and European vehicles with complex charging systems may require programming the new alternator's unique id

With the car details.

Yes, a new or replacement alternator should be coded (programmed) to the car's Battery Management System (BMS) in a Jaguar XF 3.0. While the car may run without immediate damage, failing to code it is considered irresponsible by mechanics and can lead to issues with the charging system's efficiency and lifespan of components

[Kevin Wood]

Seem absolutely daft that it would need to be coded. Alternators don't have any unique characteristics that might need to be coded in.

Then again, modern cars are daft.

[Marks DTM Calib]

It is a LIN controlled alternator (as are most from the last 10+ years)

Topix states:

On 3.0L vehicles, the charging system consists of a 130 A output generator and regulator assembly. The generator and regulator assembly generates electrical power for the vehicle electrical system and maintains the battery in a charged state.

When the engine is running the generator produces an alternating current, which is converted to a direct current internally. The output from the generator is controlled by the voltage regulator (located inside the generator) and then supplied to the battery through the main battery positive cable.

The generator is mounted on the front right side of the engine and driven at approximately 3 times engine speed by the accessory drive belt. Refer to: Accessory Drive (303-05B, Description and Operation).

The output voltage required from the generator and regulator is calculated by the battery monitoring system. Refer to: Battery and Cables (414-01 Battery, Mounting and Cables, Description and Operation).

The battery monitoring system signals the calculated voltage to the ECM via the RJB and the instrument cluster. The ECM then transmits the calculated voltage to the generator and regulator on the LIN bus connection.

The ECM will over-ride the voltage value requested by the battery monitoring system if it detects a fault in the generator and regulator. The ECM also signals the instrument cluster to display a warning message if it detects a fault with the generator and regulator. Refer to: Instrument Cluster (413-01 Instrument Cluster, Description and Operation).

The regulator provides a controlled variable voltage output from the generator. Two electrical terminals are provided on the outer casing of the generator. One terminal supplies the direct current (DC) voltage output from the generator to the battery positive terminal. The second terminal provides the LIN bus connection between the regulator and the ECM.

Topix, in the replacement procedure, makes no mention of needing to code the unit.

Pretty much every type of regulator is available online

[Doctor Gollum]

Thanks Mark

Sounds like the PO got fobbed off. Mate bought the car for £300 so sounds like he can't really lose on it

[TheBoy]

Certainly the alternator on my 2010 3l diesel XJ didn't need any coding, and I imagine its a similar setup.

[Marks DTM Calib]

I think at that age they might be a Valeo or Marelli part (later are Bosch mostly), it is a pretty common design (all be it with different castings to suit different mountings for different manufacturers).

Once removed, from below it would appear, it should be obvious.

[Marks DTM Calib]

Certainly the alternator on my 2010 3l diesel XJ didn't need any coding, and I imagine its a similar setup.

It is the same system