Interfacing the Coolant System

March 2005

The coolant system, in the New Beetle, is a multi-function indicator light. However, this light is used to indicate the level of coolant, as well as the temperature of the coolant.

Here are the warning indicators states:

• When low on coolant it will blink red and sound a chime.
• When too hot it will ?? (maybe blink red?)
• When all is OK, at the right temp it will be off
• If too cool, it will be blue
• If disconnected, it will be flashing blue

Coolant Temp Sensor

Analysis

Two coolant temp sensors (G62 & G2 p. 97-67)

1. G62 is used for the ECM
2. G2 is used for the instrument panel.

The power for G2 (lilac) goes to a 10-pin connect behind the instrument panel LEFT.

The ground for G2 (brown/white) goes to a 10pin connector in the engine compartment LEFT.

This is two sensors combined into a single package.

Action

This has been tested and works. Since this is simply a dash warning light, it may need to be connected to the EV ECU to turn on the light when a high temp situation exists in the inverter/drive.

Two sensors drive this light. A temp sensor on the engine, and a coolant level sensor on the overflow bottle. To fool the temp sensor, a 110ohm resistor to ground at the instrument panel, causes the instrument panel to "think" the engine is at the right temp. The light stays off.

The coolant temp sensor

Coolant Level Sensor

Analysis

A coolant level sensor (G32 on p97-72) - this is part of the overflow bottle, it can be left intact and connected (as we are using the stock coolant reservoir). Connector is (brown/white and lilac/red)

Action

The coolant level sensor (in the coolant reservoir) has been tested and appears to work. It will be left in place.

The coolant level sensor

Engine Oil Warning Light

The engine warning light comes on when the the tachometer starts to read, and the oil sensor indicates low or no pressure.