Checking electrical components of auxiliary heater — AUDI

Measuring instruments and other items required

Portable multimeter V.A.G 1526
Adapter set V.A.G 1594
Diode test lamp V.A.G 1527

Test requirements

All fuses OK as per current flow diagram
Actuation of auxiliary heater OK
Coolant temperature less than 30°C

Checking

Switch off ignition and auxiliary heater.
On vehicles with headlight washer system:
Remove top part of air cleaner.

Detach headlight washer system reservoir from body.

Remove air duct to alternator (8-cyl. engine only).
Remove bumper and noise insulation.

=> General Body Repairs; Repair Group 63; Front Bumper
General Body Repairs
Front Bumper

Remove bolts -B-.
Remove bolts -A-.
Lower auxiliary heater slightly (leave all connections attached).
Screw in M 8 x 80 bolts (to secure lowered auxiliary heater).

Remove bolts -A- and detach holder -B-.
Remove central cover =>Page
82-148
.

Notes:

Pin assignment of connector rail corresponds to block diagram of auxiliary heater =>Page
82-177
.
Check plug contacts and connector rail for dirt and corrosion and clean if necessary.

Test step 1 (power supply for auxiliary heater)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Select measuring range: / Voltage measurement (20 V DC)
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
1.1 · 10 / and / 11 · Power supply to auxiliary heater · ▪ Ignition off / ▪ Auxiliary heater off · - approx. battery voltage · - Use current flow diagram to locate and eliminate open circuit in wiring or contact resistance in power supply or in earth connection
1.2 · 10 / and / 11 · Connection between batteries -A and -A1 · ▪ Auxiliary heater off / ▪ Engine running · - approx. alternator voltage · - Use current flow diagram to locate and eliminate open circuit in wiring or contact resistance in connection between -A and / -A1 / Use current flow diagram to check actuation and operation of battery cut-out relay -J7

Test step 2 (actuation of auxiliary heater by pre-selection clock -E111)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Select measuring range: / Voltage measurement (20 V DC)
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
2.1 · 9 / and / 10 · Pre-selection clock / -E111 cut-in signal · ▪ Ignition off / ▪ Auxiliary heater off · - Less than 2V · - Use current flow diagram to locate and eliminate short to positive
2.2 · 9 / and / 10 · Pre-selection clock / -E111 cut-in signal · ▪ Ignition off / ▪ Auxiliary heater on · - Greater than 7V · - Use current flow diagram to locate and eliminate short to earth, open circuit in wiring or contact resistance / Check pre-selection clock power supply=>Page 82-70

Select measuring range: / Voltage measurement (20 V DC)
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
2.3 · 9 / and / 10 · Cut-in function of pre-selection clock / -E111 · ▪ Ignition off / ▪ Auxiliary heater off / Set cut-in time (1, 2 or 3) to approx. / 5 minutes before actual time and activate · - At activated cut-in time, voltage changes from less than 2V to greater than 7V · - Check pre-selection clock power supply=>Page 82-70 / Replace pre-selection clock

Test step 3 (heater/heat output switch -E16)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Select measuring range: / Voltage measurement (20 V DC)
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
3.1 · 3 / and / 10 · Operation of switch -E16 · ▪ Auxiliary heater on / ▪ Switch -E16 not pressed · - Greater than 5V · - Use current flow diagram to locate and eliminate short to earth / Check switch -E16 / =>Page 82-202 / Replace auxiliary heater
3.2 · 3 / and / 10 · Operation of switch -E16 · ▪ Auxiliary heater on / ▪ Switch -E16 pressed · - Less than 2V · - Use current flow diagram to locate and eliminate open circuit in wiring or contact resistance / Replace switch -E16

Test step 4 (flame monitor -G64)

Note:

Block diagram of auxiliary heater and pin assignment => Page
82-177

Select measuring range: / Resistance measurement (20 ω)
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
4.1 · Connector contacts 14 and 15 · Flame monitor -G64 · ▪ Ignition off / ▪ Auxiliary heater off · - 2 to 4 ω · - Locate and eliminate short circuit / Replace flame monitor
4.2 · Connector contacts 14 and 10 (connector rail contact) / · ▪ Connector unplugged from connector rail (contacts 14 and 15) / ▪ Flame monitor at ambient temperature · - ∞ω · - Locate and eliminate short to earth / Replace flame monitor

Note:

As temperature rises, resistance changes from 2 to 4 ω(at ambient temperature) toapprox. 10ω(at 1000°C)

Test step 5 (glow plug -Q6, heater control unit -J162)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Select measuring range: / Resistance measurement (20 ω)
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
5.1 · 12 / and / 13 · Glow plug -Q6 · ▪ Ignition off / ▪ Auxiliary heater off · - 0.3 to 1.0 ω · - Locate and eliminate short circuit / Replace glow plug
5.2 · 12 / and / 10 · Earth connection in auxiliary heater · ▪ Ignition off / ▪ Auxiliary heater off (all components switched off) · - Less than 1ω · - Replace auxiliary heater

Note:

In the measuring range less than 1ω, a change in contact pressure is sufficient to alter the measurement result.

Diode test lamp
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
5.3 · 13 / and / 10 · Control unit -J162 (in auxiliary heater) · ▪ Ignition off / ▪ Switch -E16 not pressed / Switch on auxiliary heater · - Diode test lamp flashes or lights · - Replace auxiliary heater

Notes:

If battery voltage is greater than 10.5 V, current supply for glow element is pulsed (to limit temperature).
Test step 5.3 must be completed within 80 s.

Test step 6 (actuation of metering pump -V54)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Diode test lamp
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
6.1 · 4 / and / 10 · Actuation of metering pump -V54 · ▪ Ignition off / ▪ Switch -E16 not pressed / Switch on auxiliary heater at pre-selection clock · - Diode test lamp starts to flash approx. 32 s after switching on auxiliary heater / Metering pump -V54 is actuated (pulsed) · - Use current flow diagram to locate and eliminate short to earth in wiring to metering pump / / Check actuation of metering pump =>Page 82-205 / Replace auxiliary heater

Test step 7 (recirculating pump -V55)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Select measuring range: / Current measurement (20 A) / ▪ Connector unplugged from connector rail (contacts 1 and 2) / ▪ Link between connector contact 1 and connector rail contact 10
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
7.1 · Connector contacts 2 and 11 (connector rail contact) · Recirculating pump -V55 · ▪ Ignition off / ▪ Auxiliary heater off · - Less than 1.6 A / Operation of recirculating pump · - Locate and eliminate short circuit / Replace recirculating pump

Select measuring range: / Voltage measurement (20 V DC) / ▪ All connectors attached to connector rail
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
7.2 · 2 / and / 10 · Control unit -J162 (in auxiliary heater) · ▪ Ignition off / ▪ Switch -E16 not pressed / ▪ Auxiliary heater on · - Greater than / 10 V / Operation of recirculating pump · - Replace auxiliary heater

Note:

In the event of problems with poor heat output:

Check incorporation of auxiliary heater into coolant circuit.
Check proper operation of non-return valves in coolant circuit.
Check for cross-sectional constrictions in coolant circuit.
Check operation of air conditioner.

To check maximum heat output of auxiliary heater, unplug connector to both valves of pump/valve unit (valves are open in rest position; coolant can flow through heat exchangers without regulation).

Test step 8 (combustion air blower -V6)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Select measuring range: / Current measurement (20 A) / ▪ Connector unplugged from connector rail (contacts 5 and 6) / ▪ Link between connector contact 5 and connector rail contact 10
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
8.1 · Connector contacts 6 and 11 (connector rail contact) · Combustion air blower -V6 · ▪ Ignition off / ▪ Auxiliary heater off · - Less than 4.5 A / Operation of combustion air blower · - Locate and eliminate short circuit / Replace combustion air blower

Select measuring range: / Voltage measurement (20 V DC) / ▪ All connectors attached to connector rail
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
8.2 · 5 / and / 6 · Control unit -J162 (in auxiliary heater) · ▪ Ignition off / ▪ Switch -E16 not pressed / ▪ Auxiliary heater on · - Operation of combustion air blower / approx. 4.5 to 7V (on starting and in part load mode) / Greater than / 10 V (in full load mode) · - Replace auxiliary heater

Notes:

Auxiliary heater starts up in part load mode and switches smoothly to full load mode.
In the event of problems with auxiliary heater operation:

- Check air intake area of combustion air blower unit.

- Check exhaust system.

- Check fuel delivery of metering pump.

- Check CO2 level in exhaust gas.

- Dismantle auxiliary heater. Check seals between combustion air blower unit and auxiliary heater/burner element as well as burner element.

Test step 9 (actuation of operating and display unit for air conditioner/Climatronic -E87/fresh-air blower -V2)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Diode test lamp
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
9.1 · 10 / and / 7 · Actuation of auxiliary heater relay -J8 · ▪ Ignition off / ▪ Switch -E16 pressed / Switch on auxiliary heater at pre-selection clock · - Diode test lamp lights / Operating and display unit/fresh-air blower starts up · - Use current flow diagram to locate and eliminate short to earth, open circuit in wiring or contact resistance / Perform air conditioner self-diagnosis => Air Conditioner Workshop Manual / Check actuation / =>Page 82-201

Test step 10 (condition of second battery -A1, power supply for auxiliary heater)

Note:

Block diagram of auxiliary heater and pin assignment =>Page
82-177

Select measuring range: / Voltage measurement (20 V DC)
Test step · Contact · Testing of · ▪ Test conditions / - Additional work · Specification · Remedies if specification not attained
10.1 · 10 / and / 11 · Condition of -A1, power supply to auxiliary heater · ▪ Ignition off / ▪ Auxiliary heater on / ▪ Switch -E16 not pressed · - Greater than / 10 V · - Use current flow diagram to locate and eliminate open circuit in wiring or contact resistance in power supply or in earth connection / Check condition of battery -A1; charge or replace battery if necessary

Note:

If voltage at auxiliary heater drops below 10 V (for more than 20 s), heater is switched off (to protect battery against exhaustive discharge).