Porsche 928 ST1991 Owner's Manual page 38

does not go out after starting the engine,
there is a malfunction in the electrical sys-
tem. If this is the case, contact your Porsche
dealer. If the light flickers or stays on while
you are driving, the V-belt may be loose or
broken. The belt should be retensioned or re-
placed. The fault may also be in the regulator
or the alternator itself. In this case, keep elec-
trical consumption at a minimum and drive
to the nearest workshop.
Coolant temperature gauge
and warning light
Needle in left field - engine is cold
As long as needle is in left field, avoid high
speeds and high engine rpm, until engine
has reached normal operating tempera-
ture. Do not lug the engine.
Needle in center field - normal
Under normal driving conditions, needle
should remain in center field. The needle
may reach the right field, especially at high
engine loads, but should return to "normal"
when engine load is reduced.
38
Needle in right field - engine is warm
If needle enters the red mark, the engine is
overheating. The warning light comes on
and fault message appears in the informa-
tion system display. Reduce speed and en-
gine rpm. If it does not cause the tempera-
ture to decrease, pull off the road, turn off
the engine and let it cool down.
Coolant temperature warning light
If the warning light comes on, check that the
fans are working. See section "Cooling fan
control". If the fans are not rotating, the
power supply to the fan control is defective.
If the problem cannot be readily located, be
sure the engine has cooled down suffi-
ciently. Then drive to the nearest Porsche
dealer, but carefully watch the coolant temp-
erature gauge and the warning light. Try to
avoid engine idling, very low speeds and en-
gine speeds in excess of 4000 rpm.
For other details refer to "Cooling System".
Warning lights
Vehicles having this indicator light are equip-
ped with a special on-board diagnostic sys-
tem. This system monitors the various com-
ponents of the Emission Control System.
The light comes on when the ignition is
switched on. It will go out after the engine is
started, if you have started without depres-
sing the accelerator pedal. This is to assure
you that the malfunction indicator light is
functioning properly.
If the light does not go out after starting the
engine, or if it should come on always while
driving, this indicates that there is a malfunc-
tion in the Emission Control System. Have
the cause corrected promptly by an au-
thorized Porsche dealer or a qualified work-
shop.
Each monitored component in the Emission
Control System has been coded. In case of
a malfunction the respective component will
be identified and the fault stored in the con-
trol unit's memory.
The stored data can be displayed by a flash-
ing code of the malfunction indicator light to
assure an accurate diagnosis. For further in-
formation of the codes and repair proce-
dures, see your authorized Porsche dealer.