Audi Workshop Service and Repair Manuals

Required measuring and testing equipment:

• ◆ Vehicle diagnostic, testing and information system VAS 5051 with test leads VAS 5051/7, the DOS measuring cable VAS 5051/8, 50A current probe VAS 5051/9
• ◆ Voltage tester V.A.G 1527 B
• ◆ Measuring tool set V.A.G 1594 A

Test requirements

• ‒ All fuses OK in accordance with current flow diagram.
• ‒ Battery -A is sufficiently charged.
• ‒ The fault memory was interrogated =>Page 01-24 and any displayed faults rectified.

Check additional heater actuation and electrical connections

• ‒ Switch ignition off.
• ‒ Remove the engine air intake pipe if necessary.

=> Relevant Workshop Manual, Engine, Mechanical Components

• ‒ → Remove the additional heater from the vehicle by removing the hexagon nut -A- and the bolts -B-.
• ‒ Remove the intake silencer -C-.
• ‒ Carefully pull the additional heater towards the engine.

• ‒ → Detach connectors -A- and -B- from the heater unit.

List of electrical tests

Test step 1

Power supply and earth connection

Notes:

• ◆ Depending on the last operating condition and the coolant temperature in the additional heater, the current consumption of the additional heater at rest may amount to a maximum of 60 mA for a period of 5 hours after switching off. In this period of time, the coolant cooldown is calculated by the -J162 control module for the time after switching off.
• ◆ The -J162 additional heater control unit at-rest current consumption is smaller than 2 mA after a maximum of 5 hours have elapsed.

Test step 2

Actuation of additional heater

Notes:

• ◆ Contact 3 of the 6-pin connector on the additional heater is connected to the engine control unit on vehicles with diesel engines.

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

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

• ◆ If in "diesel" type additional heaters, contact 3 in connector B is connected to earth, the additional heater is switched on.
• ◆ If the additional heater does not switch on for vehicles with diesel engine, check the adaption in adaption channel "10" => Page01-88

Test step 3

Connection from additional heater to the metering pump

Notes:

• ◆ Contact 6 of plug B is also connected to the engine control unit on vehicles with diesel engines. Engine control unit uses clock signal to metering pump to incorporate fuel consumption of additional heater into consumption signal when engine is running.

=> Relevant Workshop Manual, Diesel Direct Injection and Preglow System

• ◆ Internal resistance of metering pump is 4.1 ω+/- 0.2ω

Test step 4

Connections not connected on the additional heater (provided for the auxiliary/additional heater version)

Note:

For auxiliary/additional heater, the function "auxiliary heater" is switched on and off via this input (e.g. by a preselector).

=> Audi A8 auxiliary/additional heater

=> Audi A6 auxiliary heater

Note:

If contact 5 of connector B is connected to earth, the auxiliary/additional heater is not switched on as auxiliary heater once voltage is applied to contact 1 of connector B, only the output to the actuation of the -E87 operating and display unit / the heater controls is switched on (auxiliary ventilation).

=> Audi A8 auxiliary/additional heater

=> Audi A6 auxiliary heater

Note:

Using this output, the -E87 operating and display unit / heater controls is actuated for an auxiliary / additional heater as soon as the specified coolant temperature in the auxiliary / additional heater is reached while in the auxiliary heater operation, or at all times if in auxiliary ventilation operation.

=> Audi A8 auxiliary/additional heater

=> Audi A6 auxiliary heater

Checking additional heater components

• ‒ Switch ignition off.
• ‒ Remove the engine air intake pipe if necessary.

=> Relevant Engine Workshop Manual, Mechanical Components

• ‒ Detach the additional heater from the vehicle =>Page 01-107
• ‒ → Detach connectors -A- and -B- from the heater unit.

• ‒ → Detach the bracket from the additional heater by removing bolts -A- and -B-.

• ‒ → Lever off the cover -A- using a screwdriver.

List of electrical tests

Test step 1 (glow plug with flame detector -Q8)

• ‒ → Unplug the connector -C- from the additional heater.
• ‒ Measure resistance between contact 1 and housing of heater at connector -C-.

Specified value:

∞ω

• ‒ Measure the resistance between contacts "1" and "2" on connector -C-

Specified value:

Less than 1 ω

Rated value:

0.236 ω +/- 0.033 ω(at 25 °C)

Notes:

• ◆ Resistances of less than 1 ωcan no longer be measured with the required degree of accuracy using workshop equipment. This test therefore only permits detection of serious component damage.

• ◆ The heater control unit -J162 detects whether or not a flame has formed in the heater using the characteristic resistance curve of -Q8.
• ◆ If a voltage of 9 V is applied to the glow plug with flame detector, the current input is between 9 and 12 A.

Test step 2 (combustion air blower -V6)

• ‒ → Unplug the connector -B- from the additional heater.
• ‒ Measure resistance between contact 1 and housing of heater at connector -B-.

Specified value:

∞ω

Notes:

• ◆ If a voltage of 12 V is applied to the combustion air blower -V6 the current input is between 2 and 3 A.
• ◆ The combustion air blower -V6 internal impedance is between 3 and 6ω (40 ω if the combustion air blower has not been running for some time) Since resistances of less than 10ωcan no longer be measured with the required degree of accuracy using workshop equipment, internal impedance testing can only be used to detect serious component damage.

Test step 3 (recirculating pump -V55)

Note:

The Audi A2 currently uses no recirculating pump.

• ‒ → Unplug the connector -A- from the additional heater.
• ‒ Measure resistance between the two contacts (contacts 1 and 2) and the housing of the heater at connector -A-.

Specified value:

∞ω

Notes:

• ◆ If a voltage of 12 V is applied to the recirculating pump -V55 the current input is between 1 and 1.5 A.
• ◆ Internal impedance cannot be measured at the recirculating pump -V55 (this is prevented by the electronics in the recirculating pump).