406 Alternator not charging

Created: 10. 06. 2008
Updated: --. --. ----

Peugeot 406 Coupé, D9, ES9J4, XFZ.

Battery or charge light on.
Message on display - Battery charge Fault -
Cabin fan not operating.
Air conditioning compressor clutch will not engage.

No diagnostic trouble codes to indicate any faults.
Alternator appeared to be charging with a system at 14.2 volts with the engine idling.
The charge light did not extinguish after disonnecting the axitation wire from the back of the alternator, as would be expected in the presence of an alternator fault.
The exitation wire was found to be short circuited to earth.

Faulty engine running signal relay.
Short circuit in the relay's control circuit.

The BSI looks for a positiv voltage from the exitation wire. (BSI 26 Way Yellow connector terminal 14) 0 Volts at the BSI due to current drain at the relay. Consequently the BSI activates the charge failure warnings.

The contacts of the relay remained open with the engine running. The BSI did not authorize A/C clutch and cabin fan operation in the absence of the engine running signal.

Image: Location of the relay.

Image: Enlarged view of the relay.

Replace the engine running signal relay.

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