Volkswagen Workshop Service and Repair Manuals > Golf Mk4 > Power unit | Direct injection and glow plug system with distributor pump as of 05.99 | Fuel preparation system Diesel injection | Checking components and functions

Checking fuel temperature senderG81

Checking fuel temperature sender -G81-

Special tools and workshop equipment required

t	Fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- with diagnosis cable -V.A.G 1551/3-

t	Adapter cable, 121-pin -V.A.G 1598/31-

t	Hand multimeter -V.A.G 1526C- or multimeter -V.A.G 1715-

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

t	Current flow diagram

Test procedure

–	Connect fault reader -V.A.G 1551- or vehicle system tester -V.A.G 1552- and select engine electronics control unit with “address word 01”. Engine must be idling. (Connecting fault reader and selecting engine electronics control unit → Chapter.)

Indicated on display:

–	Press buttons 0 and 8 for function “Read measured value block” and confirm entry with Q button.

Rapid data transfer                 HELP

Select function XX

Indicated on display:

–	Press buttons 0, 0 and 7 for “Display group number 7” and confirm entry with Q button.

Read measured value block          HELP

Input display group number XXX

Indicated on display:

–	If no realistic display appears in display zone 1 or a substitute temperature of -5.4°C is displayed, check fuel temperature sender -G81- and line connections to sender as follows:

–	Press → button.

–	Press buttons 0 and 6 for function “End data transfer” and confirm entry with Q button.

–	Switch off ignition.

Read measured value block 7          ->

15.4°C             15.9°C        16.7°C

–	Disconnect 10-pin connector for fuel temperature sender -G81- (connector to injection pump quantity adjuster).

–	Measure sender resistance at connector contacts 4+7.

Specification see diagram.

Scale A shows resistance values for temperature range 0..50°C and scale B the values for temperature range 50..100°C.

Examples:

t	30 °C corresponds to a resistance of 1500..2000 Ω

t	80 °C corresponds to a resistance of 275..375 Ω

If the specification is not achieved:

–	Renew injection pump → Chapter.

If the specification is attained:

–	Connect adapter cable, 121-pin -V.A.G 1598/31- to control unit wiring harness.

–	Check wiring between adapter cable, 121-pin -V.A.G 1598/31- and connector for open circuit referring to current flow diagram.

Contact 7+ socket 111 Contact 4+ socket 103 Line resistance: max. 1.5 Ω

–	Also check wiring for short to one another, short to vehicle earth and short to battery positive.

Specification: ∞ Ω.

If no fault in lines is detected:

–	Renew diesel direct injection system control unit -J248- → Chapter.

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