Starter fault diagnostics (VW Passat B3)

When the starter does not rotate, first of all it is necessary to check whether the voltage required for its operation is supplied to terminal 50 of the traction relay, the value of which should not be lower than 8 volts. If the voltage is less than the specified value required by the electrical circuit, check the wires included in the electrical circuit of the starter. You can check whether the starter works when the full voltage of the battery is supplied as follows.

Prerequisite for verification: The wire connection points must be firmly tightened and must not be oxidized.

Without engaging any gear, turn on the ignition. Then, using a wire with a cross-section of at least 4 sq. mm, make a jumper between terminals 30 and 50 of the starter, see also electrical diagram.

If the starter engages the gear perfectly, then the fault lies in the electrical wires that supply voltage to the starter.

If the starter does not engage the gear, it must be checked in the removed state.

If the starter turns too slowly and cannot turn the engine shaft, the reasons may be as follows:

• Insufficient current supply due to weakened or oxidized connections.
• The brushes do not fit snugly against the collector, are jammed in their guides, are worn out, damaged, oily or dirty.
• The collector has dents, is burnt or dirty (needs to be sharpened or replaced).
• The voltage supplied to terminal 50 is too low, less than 8 volts (check the ignition and starter switch or traction relay).
• The bearing is broken.
• Traction relay defective.