Audi Workshop Service and Repair Manuals

Electrical test of map-controlled engine cooling system

Special tools and workshop equipment required

t	Hand-held multimeter -V.A.G 1526 A- or -V.A.G 1526 B-

t	Auxiliary measuring set -V.A.G 1594 A- or -V.A.G 1594 C-

t	Adapter cable, 121-pin -V.A.G 1598/31- (test box)

Test sequence   WARNING The radiator fan motors may start up.   Note Diagnosis of map-controlled engine cooling system has been performed → Chapter. –  Take off engine cover panel -arrows-. –  Start engine and run at idling speed.

–  Unplug electrical connector -1- at coolant temperature sender -G62-.   Note Unplugging the connector from the coolant temperature sender -G62- causes the engine control unit to detect a fault in the map-controlled engine cooling system. It then constantly actuates the thermostat using full battery voltage. –  Unplug connector -2- at map-controlled engine cooling thermostat -F265-.

–  Connect multimeter (voltage test range) between contacts -1- and -2-. l  Specification: Approx. battery voltage (after a short delay) If specification is not obtained: –  Connect multimeter to measure voltage between contact -1- and earth. l  Specification: approx. battery voltage –  Switch off ignition.

If specification is not obtained: –  Check the wiring from contact 1 of the connector to the power supply relay for Simos control unit -J363--item 2- (below cover on left of bulkhead) for open circuit using the current flow diagram. –  Repair wiring connection if necessary. If no fault is found: –  Connect adapter cable, 121-pin -V.A.G 1598/31- (test box) to connectors of wiring harness; do not connect engine control unit. Connect earth clip of test box to earth → Rep. Gr.24.   Caution To avoid damage to the electronic components, select the required measuring range and observe test conditions before connecting the test leads.

–  Check for open circuit in the following wiring connection:

Connector Contact	Adapter cable, 121-pin -V.A.G 1598/31- (test box) Socket
-2-	116

–  Repair wiring connection if necessary. If no fault is found: –  Check function of thermostat → Chapter. –  Plug in electrical connectors. –  Interrogate and erase the fault memory for engine control unit, as faults are stored when the connectors are unplugged → Vehicle diagnosis, testing and information system VAS 5051.