More VW TDI Glow Plug Diagnostics
Car Commando from the Field. More TDI Diagnostics here:
Right from the EDR sight, thought I'd share this with the group.
Currently in Denver in 6" of snow and 10 below :-(
There are several vehicle models on which the glow plug position does not coincide with cylinder number, (eg. trouble code P0671 specifies glow plug number 1 but glow plug number 1 is
actually in cylinder number 4).
The only way to be sure which glow plug is faulty is to test all of them. This particular glow plug system on the BHW engine code, supplies 6VDC to the glow plugs.
THIS IS A NORMAL READING. To get momentary or no glow plug operation in ambient temperatures above 46 degrees F.
1. The code is for glow plug number 1 circuit. Codes for the 4 glow plug circuits are: P0671, P0672,
P0673 and P0674.
2. With the ignition switch turned off, disconnect the Coolant Temperature Sensor (CTS).
3. Turn the ignition to the on position. The glow plug relay should energize for about 20 seconds (glow system self-test) and supply the glow plugs with 6 volts.
4. Check wiring between the glow controller and glow plugs for open or high resistance.
5. If OK, test current draw of each plug, by applying battery voltage through an ammeter and comparing draws. They should be the same and the initial draw should be in the range of 12 to 18A, dropping to a minimum of 6A, after 15 seconds.
6. A difference in amperage draw of 3 amps between glow plugs can cause a trouble code to set. Be sure that all glow plugs are within 3 amps of each other on initial application of power and also during normal glow period.
7. If glow plugs fail testing, always replace them as a set.