Testing glow plugs on a VW T4 111kw AHY with a testing device

The friendly Beru representative lent me his glow plug tester. I disconnected the connector at the front of the engine block, which connects to the glow plug wiring harness, and from there, I directly powered the plugs with the tester. The device then energizes the glow plug for 10 seconds and determines whether it's good or defective. After testing all the plugs, they are all defective. However, they are Beru plugs and are at most 1 year old. Could there be a wiring harness problem? When it's cold, the engine sputters for a few seconds.

Have you ever tried using a multimeter to check it?
- Voltage measurement plug vs. Mass.
- Resistance measurement of the glow plugs.
- Current measurement through the candle (20A range).

Herbert.

PS - I've moved this here.

sebv6 wrote:

The friendly Beru representative lent me his glow plug testing device. At the front of the engine block, I disconnected the connector to the glow plug wiring harness and, from there, directly powered the plugs with the testing device. The device then energizes the glow plug for 10 seconds and determines whether it is good or defective. After testing all the plugs, they are all defective. However, they are Beru plugs and are at most 1 year old. Are there any wiring harness problems? When it's cold, the engine sputters for a few seconds.

Frankly, I don't think much of this test thing; I find it unlikely that all 5 glow plugs, which are 1 year old, should be defective – unless the preheating relay is stuck in the "glow" position. Check! Also, as Herbert already wrote, check the glow plugs! You can also remove the glow plugs and observe the glow process while they are removed.