Volkswagen Workshop Service and Repair Manuals > Golf Mk4 > Power unit | Direct injection and preglow system with distributor-type pump to 04.99 | 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 -V.A.G 1598/22-

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

t	Adapter 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 control unit for engine electronics with “address word 01”. Engine must be idling. (Connect fault reader and select engine electronics control unit → Chapter.)

Indicated on display:

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

Rapid data transfer                 HELP

Select function XX

Indicated on display:

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

Read measured value block           HELP

Input display group number XXX

–	Indicated on display:

–	Check value for coolant temperature in display zone 4.

The temperature value must rise equally without interruption.

–	In the event of a fault, the fuel temperature is displayed as a substitute.

–	If no realistic display appears in display zone 4 or the fuel temperature is displayed as a substitute, check coolant temperature sender -G62- and wiring connections to sender as follows:

–	Press → button.

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

–	Switch off ignition.

Read measured value block 7          ->

15.4 °C            15.9 °C       16.7 °C

–	Pull connector off coolant temperature sender -G62- → Chapter.

–	Measure resistance between sender contacts 1+3.

For 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 reached:

–	Renew the coolant temperature sender -G62-.

If the specification is attained:

–	Connect adapter -V.A.G 1598/22- to control unit wiring harness.

–	Check wiring between adapter and 4-pin connector for open circuit using current flow diagram. Contact 3+socket 54 contact 1+socket 70.

Cable 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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