Audi Workshop Service and Repair Manuals

Notes:

• ◆ For testing the operation of the coolant temperature sender, see also "Reading measured value block", Display Group 003, display zone 3.
• ◆ Fitting location of coolant temperature sender
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Special tools, testers and auxiliary items

• ◆ Hand multimeter V.A.G 1526 or V.A.G 1526 A
• ◆ Fault reader V.A.G 1551 (or vehicle system tester V.A.G 1552) with cable V.A.G 1551/3
• ◆ Adapter set V.A.G 1594

• ◆ Test box V.A.G 1598/22

• ‒ Unplug connector on coolant temperature sender.
• ‒ → Test resistance between contact 1 (earth) and contact 3 (signal) on sender.

→ Area A shows resistance values for temperature range 0...50°C and area 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 value does not match the specification, fit a new sender.

If the value does match the specification, test the wiring between the sender and the engine control unit as follows:

• ‒ Connect test box V.A.G 1598/22 to the wiring harness for the engine control unit.
  => Page 24-8

• ‒ → Test for open circuit in earth wire between contact 1 on coolant temperature sender connector and socket 67 on test box.

Specification: max. 1 ω.

• ‒ Test for open circuits in signal wire between contact 3 on coolant temperature sender connector and socket 53 on test box.

Specification: max. 1 ω.

• ‒ Test for short circuits between the two wires.

• ‒ → If values do not match specifications, rectify short circuits or open circuits in wiring between coolant temperature sender connector and control unit connector.

• ‒ If there are no short circuits or open circuits and the coolant temperature sender is OK, fit a new engine control unit.
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