Glow plugs, testing

With the pre-glow system and extended glow period the current draw of each glow plug is a constant, approx. 8 amps, during the extended glow period with the engine running.

Current draw:

• 32 amps: all four glow plugs OK
• 24 amps: one glow plug malfunctioning
• 16 amps: two glow plugs malfunctioning
• 8 amps: three glow plugs malfunctioning
• 0 amps: all four glow plugs malfunctioning

The current draw can only be accurately measured when Battery Positive Voltage (B+) is greater than 11.5 Volts.

• Remove electrical connection and buss bar for glow plugs.
• Connect US 1115, VAG 1527B or equivalent voltage tester to Battery positive (+) terminal and connect second probe to each glow plug in turn.

LED lights up: glow plug OK

LED does not light up: replace glow plug