This Preliminary Information communication provides information to the technician about vehicles that may have a Battery Saver Message or red Battery Indicator displayed in the Driver Information Center. Technician may find Diagnostic Trouble Code P0AF8 set in history. Technician will need to the 12 volt battery using the GR8 Battery tester. The technician will need to perform the Direct current Power Conversion Test published in Global Service Information to check for maximum current and voltage output. This test requires the use of a Carbon Pyle load tester. In addition, the technician can select the 14 Volt Power Module Control Function in the Engine Control Module and Accessory Power Module Setpoint in the Body Control Module by using the Scan Tool in order to check that the system is able to respond to current loads. If the test fails, if there were low voltage Diagnostic Trouble Codes or P0AF8 was set, the technician should confirm that the 200 amp fuse located in the X50D Fuse Block is torqued to correct specification. Technician should check the voltage on both sides of the 200 amp Fuse while there is a load applied and comparing the voltage readings. Voltage drop can be checked from the positive battery post to the Accessory Power Module side of the 200 amp fuse as well. If the Accessory Power Module will output current under a load but the voltage is low on both sides of the fuse when compared to the voltage output at the Accessory Power Module, check the following Service Information for any other Diagnostic Trouble Codes that may have led to the low voltage condition, Accessory Power Module output terminal is clean and torqued to specification, The Accessory Power Module output cable ring terminal is properly seated to the Accessory Power Module output terminal post and its condition, and test the voltage drop on the ground cables to the engine block, transmission, body and chassis to ensure they are within specification.
