Alternator Warning Lamp Illuminated in Instrument Cluster, DTC P0625 Set (Clean Terminals)

This bulletin is being updated due to further revisions to vehicle calibration. Please discard all copies of Issue 1 and Issue 2 of this bulletin and replace them with Issue 3.

Customers may comment that the alternator warning lamp is displayed in the instrument cluster and the battery light is illuminated. Technicians may find DTC P0625 (alternator F terminal low voltage) set.

DTC P0625 sets when the F terminal duty cycle drops below 4.98% for more than 15 seconds. Investigations have shown that this may be caused by the conservative calibration applied to the Regulated Voltage Control, which controls battery charging, in vehicles built prior to March 2007.

Further investigations have shown that excursions can be experienced especially under high temperature operation which may exceed this threshold, even though there is not fault in the system, and the battery charge is not affected. As a result, the parameters which will cause this code to set have been revised in the eCU calibration, effective July 2007 vehicle build. The revised ECu calibration is included in TIS CD 9 (September 2007).

Investigation of vehicles built prior to March 8, 2007 has also indicated that fretting corrosion in the X1 connector pins 1 and 2 on the alternator to be a potential cause of loss of continuity in the charging circuit, and must also be considered when investigating complaints of P0625. Fretting corrosion causes high resistance in the circuit which leads to an open circuit condition. The corrosion is aggravated by high temperatures and normal engine vibration.

After confirming that this DTC is set and that the alternator is charging correctly, perform the following procedure.

Vehicles Built Prior to VIN 6G1MZ55H07L928723 - Reprogram the Regulated Voltage Control

SPS Programming New RVC calibration

Important: Prior to programming, ensure that the battery is fully charged.

Perform Service Programming (SPS) of the Body Control Module (BCM) from TIS2WEB or TIS DVD 2007/04 or later.

After SPS Programming

After SPS programming has been completed, it will be necessary to relearn both the brake position sensor and the SDM primary key to the BCM.

This can be done by selecting the following on the Tech 2®:

Select "Brake pedal positioin sensor learn" and follow Tech 2® prompts.

After this has been completed, select "Program SDM primary key to BCM" and follow Tech 2 prompts.

After programming has completed, perform a vehicle wide DTC check and clear all DTCs.

If the vehicle is equipped with Rear Seat Entertainment (RSE), remove the RSE fuse (fuse 1) in the trunk compartment fuse box for 30 seconds.

Vehicles Built Prior to VIN 6G1MK52B98L956123, June 5, 2007 Build Date - Reprogram ECU from TIS CD 32007/9 or later to:

Confirm Integrity of F Terminal at Alternator Connection - Vehicles Built Prior to VIN 6G1MZ55H07L928723

1. Disconnect alternator harness connector X1.
2. Check the terminal retention and condition of connector X1.
3. Clean the terminals in the X1 connector wiring harness and the alternator connector with terminal contact cleaner.
4. Apply Nyogel grease to the terminals in the wiring harness connector.

Notice: Failure to clean the pins properly or work the Nyogel grease into the terminals can lead to repeat failure.

5. Reconnect the wiring harness connector and then disconnect again. Repeat this three times to ensure Nyogel grease is thoroughly worked into the terminals and connector

For vehicles repaired under warranty, use: