Exhaust System Temperature Indicator

� VEXH Warning:

WIRING DIAGRAM

EXH Warning: Component Location:

COMPONENT LOCATION VIEW

EXH Warning: Component ID:

COMPONENT ID
22A Main fuse board in the dashboard.
47L EXH warning lamp in the main instrument display panel.
416 Relay, EXH warning, on main relay board in the dashboard.
417 EXH temperature sensor, on the three-way catalytic converter.
540 Main instrument display panel on the dashboard.

Grounding Points
G33S Grounding point, connector bracket (Signal) below the left-hand A pillar.
G34S Grounding point, control module bracket (Signal) below the right-hand A pillar.

DESCRIPTION OF OPERATION
Cars for certain markets are equipped with a monitoring system for catalytic converter overheating.

The system consists of:
^ Temperature sensor 417
^ Electronic relay 416
^ Warning lamp 47L

When catalytic converter temperature reaches 825 +/-25 °C, the warning lamp lights up and remains on until the temperature drops by about 10 °C.

When current (+15 circuit) is applied to pin 4 of the relay, the warning lamp is connected to ground and lights up for about 3 seconds. The lamp will not light up again unless the catalytic converter temperature exceeds the preset limit.

As the temperature rises, the current between pins 3 and 1 of the temperature sensor changes. When the change in the resistance of the sensor is sufficiently great, the relay function is activated and the warning lamp lights up.

Similarly, the warning lamp goes out when the temperature drops or when current (+15 circuit) is no longer applied to the relay, i.e. when the ignition is switched off.

A heat shield designed to prevent ground vegetation from catching fire is mounted under the three-way catalytic converter and intermediate pipe.

FAULT DIAGNOSIS HINTS
When current (+15 circuit) is applied to pin 4 of the relay, the warning lamp is grounded and lights up for about 3 seconds. If it remains alight, there is a break in the thermostat circuit. Normally, the warning lamp will go out and stay out until the temperature exceeds the preset limit.
1. Also check that fuse 17 is intact and that current is supplied to the temperature sensor and the relay.
2. Also check the connectors, wiring harness and ground connections.