Audi Workshop Service and Repair Manuals

Electrical additional heater is activated by control unit for diesel direct injection system -J248 when following conditions occur at the same time:

• ◆ Ambient or intake manifold air temperature measured (at start of engine) less than 5 °C
• ◆ Refrigerant temperature less than 70 °C
• ◆ Engine speed above 800 rpm
• ◆ Other actuation conditions:

=> Relevant Workshop Manual Diesel Direct Injection and Glow Plug System; Repair group 01; Reading measured value block

Test sequence

• ‒ Check low heating output relay -J359 or high heating output relay -J360:

=> Relevant Workshop Manual Diesel Direct Injection and Glow Plug System; Repair group 01; Final control diagnosis

If the relays are OK:

• ‒ Test wiring for open circuit and short to positive or earth.

=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder

• ‒ → Check earth wiring to refrigerant stump -A- (in which the glow lamps are screwed into) to the cylinder head.

If no wiring fault is detected:

• ‒ Check glow plugs:
• ‒ Remove the electrical wiring -B- from the glow plugs.
• ‒ Connect multimeter for resistance measurement to the glow plug and measure resistance between glow plug and refrigerant stud -A-.
• ‒ Specified value: 0.5...0.7 ωat room temperature

If specified value is not attained:

• ‒ Replace glow plug.
• ‒ Check refrigerant level:

=> Relevant Workshop Manual Engine, Mechanical Components; Repair group 19