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 coolant temperature senderG62

Checking coolant temperature sender -G62-

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:

–	Check coolant temperature value in display zone 4. The temperature value must Increase uniformly and without interruption.

–	In case of faults the fuel temperature or - 4.5 °C is displayed as a substitute.

–	If no realistic display appears in display zone 4, or either the fuel temperature or -4.5°C is displayed as a substitute, check coolant temperature sender -G62- 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

–	Pull connector from sender → Chapter.

–	Measure resistance between sender contacts C+D.

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 the coolant temperature sender -G62-.

If the specification is attained:

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

–	Check wiring between 121-pin adapter cable -V.A.G 1598/31- and 4-pin connector for open circuit according to current flow diagram.

Contact 3+socket 112 Contact 4+socket 104 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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