Component Tests and General Diagnostics

Troubleshooting - (Part 1 Of 2):

Check Generator pulley with freewheel clutch (only 4-cylinder TDI engine, code AHH & Bosch generator)

Generator ribbed belt pulleys on 4-cylinder TDI engines (code AHH with Bosch generators only) may be equipped with a freewheeling clutch mechanism. These pulleys are identified by a protective cap in the center of the pulley

The free wheel clutch momentarily free wheels the drive to the generator pulley/generator whenever the ribbed belt whips or oscillates due to variable belt loads (for example, during A/C operation or when switching on high current electrical consumers etc.). The free wheel clutch ensures driving force to the generator is applied in a clockwise rotation only

Before proceeding with any generator/voltage regulator checks on Bosch generators with freewheeling clutch, always check operation of clutch first.


CAUTION: Due to the high ancillary loads on the ribbed belt, the freewheel clutch pulley assembly MUST be torqued as specified in the Repair Manual (when removing and installing pulley assembly). If not torqued, the pulley assembly could malfunction and affect charging system operation.

Required for checking:

^ Multi tooth adapter 3400

Prerequisite:

^ Ribbed belt tension and generator mounting OK.

Troubleshooting - (Part 2 Of 2):

Checking Generator (GEN) and Voltage Regulator (VR) using Sun VAT 40

The following is required for troubleshooting:
^ Volt Amp tester Sun VAT 40
^ Connector kit VW 1594
^ Valid wiring diagram


NOTE: Always follow complete charging system test procedures supplied with Volt-Amp tester Sun VAT 40.


Test conditions:

^ Ribbed belt tension and generator mounting OK
^ Function of ribbed belt pulley with freewheeling clutch OK (if equipped)
^ Ground connections OK