SEAT Workshop Service and Repair Manuals

Note:

The engine control unit will use a replacement value for an engine start (start temperature replacement value) as soon as there is a fault stored in the fault memory, which affects the coolant temperature sender (G62). The temperature then rises according to a model stored in the control unit. When the engine has reached normal working temperature a fixed replacement value will be displayed after a certain period. This fixed value is also dependent upon the intake air temperature.

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3
• ◆ Test box V.A.G 1598/31
• ◆ Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
• ◆ Adapter set V.A.G 1594
• ◆ Current flow diagram

Test conditions

• ● Engine must be cold.

Test sequence

Note:

Only gold-plated contacts may be used to service contacts in the connector for the coolant temperature sender.

• ‒ Connect the fault reader V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control unit with the "Address word" 01.
  (Connecting fault reader and selecting engine control unit .)

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 0 and 4 for "Display group number 4" and confirm entry with Q key.

• ‒ Read off coolant temperature value in display zone 3.

1)    If a temperature is displayed which deviates greatly from the ambient temperature of the sender, check sender wiring for transfer resistances/open circuit.

• ‒ Start engine and run at idling speed.
  The temperature value must
      increase uniformly

If the specification is not obtained:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Renew coolant temperature sender (G62).
• ‒ Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page 01-16, interrogating and erasing fault memory.
• ‒ Read-out the readiness code=> Page 01-64.

Evaluating display group 4, display zone 3 - Coolant temperature

Continuation of check when display approx. -40 °C:

• ‒ → Pull the 2-pin connector off coolant temperature sender (G62) -arrow-.

• ‒ → Bridge connector contacts 1 + 2 using adapter cables from V.A.G 1594 while observing display.

If display jumps to approx. 140.0 °C:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Renew coolant temperature sender (G62).
• ‒ Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page 01-16, interrogating and erasing fault memory.
• ‒ Read-out the readiness code=> Page 01-64.

If display remains at approx. -40.0 °C:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Check wiring using current flow diagram
  => Page 24-73

Continuation of check when display approx. 140.0 °C:

• ‒ → Pull the 2-pin connector off coolant temperature sender (G62) -arrow-.

If display jumps to approx. -40.0 °C:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Renew coolant temperature sender (G62).
• ‒ Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page 01-16, interrogating and erasing fault memory.
• ‒ Read-out the readiness code=> Page 01-64.

If display remains at approx. 140.0 °C:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
• ‒ Switch off ignition.
• ‒ Check wiring using current flow diagram
  => Page 24-73

Checking wiring

• ‒ Remove battery.
• ‒ → Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.

• ‒ → Pull the 2-pin connector off coolant temperature sender (G62) -arrow-.

• ‒ → Check wire for open circuit between test box and 2-pin connector using current flow diagram.
      Contact 1 + socket 108
      Contact 2 + Socket 93
      Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another.
      Specification: ∞ω
• ‒ Check wiring additionally for short circuit to battery positive or earth.
      Specification: ∞ω

If no fault in wire is detected:

• ‒ → Measure resistance at coolant temperature sender (G62) contact 1 (signal) and 2 (earth).

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

Examples:

• ◆ 30 °C corresponds to a resistance from 1500...2000 ω
• ◆ 80 °C corresponds to a resistance from 275...375 ω

If the specification is not obtained:

• ‒ Renew coolant temperature sender (G62).
• ‒ Interrogate fault memory, if necessary, repair any faults and then erase fault memory => Page 01-16, interrogating and erasing fault memory.
• ‒ Read-out the readiness code=> Page 01-64.

If there is no fault in the wiring and the resistance measurement values are OK.:

• ‒ Replace engine control unit
  => Page 24-150.