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Fiat Punto (176) Factory Service Manual (1993-1999)09 · 55 Electrical system
09 · Electrical

Preheating control unit

Make
Fiat
Model
Punto (176) Factory Service Manual
Year
1993–1999
Section
Plug preheating system › Preheating control unit
55 Electrical systemPreheating control unit

PREHEATING CONTROL UNIT

Wiring diagram showing the preheating control unit with terminals 1, 2, 3, 4, 5, 7, 6 connected to an earth ground, a thermal switch, an ignition switch, and heater plugs
Connector pin layout and housing view of the preheating control unit showing pins 1 through 5 and sockets 6 and 7
F3 Connections
1. Earth
2. Thermal switch (NTC)
3. Ignition switch (+15)
4. Ignition switch (+50)
5. Warning light on dashboard
6. Heater plugs
7. Direct positive from battery (+30)
  • The graph in the figure shows three curves:
  • Curve A shos the PREHEATING times in accordance with the engine coolant temperature; the plugs are supplied and the warning lamp on the instrument panel is on.
  • Curve B shows the POST-HEATING times; these are counted from the time when the engine is started.
  • Curve B1 is an alternative to curve B and is the only permitted solution.
  • At the end of the POST-HEATING phase, the device switches itself off.
There are some precautions:
  1. Preheating must not be interrupted if the engine coolant temperature is less than 80 °C.
  2. The maintenance time (plugs supplied and instrument panel warning light off) is 10 seconds. It is counted from the moment when the warning light on the instrument panel is switched off.
Graph plotting preheating and post-heating times against engine coolant temperature in degrees Celsius, showing curves A, B, and B1

Parts & tools for this job For 1993 Fiat Punto

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