Exhaust System Temperature Indicator

� VEXH Warning:

WIRING DIAGRAM

EXH Warning: Component Location:

COMPONENT LOCATION VIEW

EXH Warning: Component ID:

COMPONENT ID
47L EXH warning lamp, in the main instrument display panel.
159 Distribution terminal (+15 circuit) in main fuse box behind the glove box.
416 Relay, EXH warning, located on a bracket behind the front seat member on the right-hand side.
417 Temperature sensor, EXH, on the three-way catalytic converter.

2-Pin Connector
H2-60 To the left under the right-hand front seat.

4-Pin Connector
H4-15 To the left under the right-hand front seat.

Grounding Points
G8 Grounding point, dashboard, by the left-hand front loudspeaker socket.
G24 Grounding point, right-hand seat member, under the front right-hand seat member.

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 the three-way catalytic converter temperature rises to between 800°C and 850°C, the warning lamp lights up and remains alight until the temperature drops by about 10°C.

When current (+15 circuit) is applied to relay pin 1, the warning lamp is grounded and lights up for about 3 seconds. The lamp does not light up again unless the temperature of the three way catalytic converter exceeds the limit value.

As the temperature rises, the current between pins 3 and 4 of the temperature sensor changes. When the change in the resistance of the sensor is sufficiently large, the relay function is activated and the warning lamp lights up.

Similarly, the warning lamp goes out when the temperature drops or when the supply current (+15 circuit) is broken, i.e. when the ignition is switched off.

FAULT DIAGNOSIS HINTS
When current (+15 circuit) is applied to relay pin 1, the warning lamp is grounded and lights up for about 3 seconds.

If the lamp stays on, there is a break in the temperature sensor circuit. Normally, the warning lamp goes out and does not light up unless the temperature exceeds the limit value.
1. Check that fuse 13 is intact and that current is supplied to the temperature sensor and relay.
2. Also check the connectors, wiring harness and ground connections.