8. Checking Constant Current Draw ( All Vehicle Types)

Check constant current draw with an ammeter in series between battery minus pole and car body ground point. Adherence to the work procedure steps is important to avoid false measurements.

Procedures:

- Open engine lid (4 cylinder) luggage compartment lid (6 cylinder) rear hatch (8 cylinder). Set contact switch for the interior lights to "off" position.

On 928 models leave rear hatch open. Disconnect two pin alarm wiring on rear hatch lock behind the tool plate (brown - brown/white wires).

- Switch off all consumers and lock doors.

- On 911 and 968 models from M.Y. 1992, the switch for the lights and alarm contact is located in the front lower latch. When checking constant current draw, close the latch using a screwdriver or suitable tool.

Caution:
Remember to release the latch prior to closing the hood to prevent damage to the latch.

- Set ammeter to 10 amp range and connect leads in series between battery minus and body ground point before disconnecting battery minus pole. The ammeter is used for current flow without interruption. Disconnect battery minus cable at battery and observe ammeter. If no display, switch ammeter to mA range without disconnecting leads. Measuring current draw in this manner will prevent possible sticking relays or other circuits from opening.

Waiting times:

911 Carrera 2/4 from 1989 (K) and 911 Turbo from 1991 (M): 20 minutes (climate control)

928 S4, GT, GTS: 45 minutes (cooling fan control, instrument cluster, power window /sunroof control unit)

- Maximum current draw for all models: 30 mA. If constant current draw is above 30 mA, the cause must be determined. Pull fuses and relays one at a time from the central electric board with the ammeter connected. Observe the ammeter for current drop.



Locate consumer with high current draw. Check for the presence of aftermarket electrical equipment and disconnect as necessary. If current draw is within specifications and additional current draw from aftermarket equipment results in higher than specified values, the customer/owner must be notified in writing on the Repair Order of the potential for increased battery discharge caused by said equipment. Battery discharge caused by aftermarket equipment is not a warranty matter.

Important:
Carrera 2/4 and 928 S4/GT The current draw is higher (maximum 1 amp) for a short while after connecting or switching the ammeter.

This is caused by the instrument cluster and fan control unit on 928 vehicles and the climate control unit on 911 Carrera 2/4 vehicles. Use a testing device with a fused range up to 4 amps. It should be possible to switch the tester to a 40 mA range without current interruption.

- When assuming a sticky relay may be the problem, proceed as follows: To avoid opening of the relay, connect ammeter to battery minus and body ground point before disconnecting battery minus pole. The ammeter is used for current flow without interruption. Disconnect battery cable and observe ammeter.