97 Measurement of closed-circuit current

WM 9700IN Measurement of closed-circuit current

Tools





Tools and materials

Tools

Closed-circuit current should be measured using an analogue ammeter or a digital multimeter with a long integration time (to filter out voltage peaks).









Measurement of closed-circuit current

Preliminary work on vehicle

Information

Before measuring the closed-circuit current, determine the vehicle equipment (I numbers) and establish the expected closed-circuit current with the aid of the attached table.

1. Open the front luggage compartment.
2. Using a suitable tool, e.g. upper part of lock with a suitable handle, close lower part of luggage compartment lock while keeping the luggage compartment lid open.
3. Remove ignition key, close doors and rear lid, do not lock vehicle.
4. Set the measuring instrument to the highest possible current-measuring range.
5. With two alligator clips, connect the measuring instrument to the battery ground and to the unoccupied second body ground which is always available for RHD or LHD.
6. Remove ground strap from the body and secure against contact with the body. The entire vehicle current now flows through the ammeter.

Testing

Select a measuring range which ensures that the pointer of the instrument is in the upper third of the scale, as far as possible. Switch over measuring range without interruption. Read off the measuring values after the waiting period specified in the table.

Do not switch on any electrical loads when measuring.

Information

- If the value of the closed-circuit current is higher than the value determined in the table, the cause must be established systematically.

- Recommended troubleshooting procedure: With the measuring device connected, remove the fuses of terminal 30 and the relays successively. Observe the display values of the measuring instrument when removing in order to recognise a reduction in current.

- After troubleshooting, screw the ground strap back onto the body in the proper manner.

- The measured values could vary by approx. 20%.

- The values listed in the table depend on the condition of the battery, the room temperature and the engine temperature.

Reading off the measuring range:

Read off the measuring range only after at least 60 minutes have passed since locking the vehicle.