Locks - Central Locking System Supply Pump Testing
REF.NO. 80/12TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS
DATE: April, 1982
SUBJECT:
CHECKING CENTRAL LOCKING SYSTEM FOR PROPER FUNCTIONING
MODEL 126
We have established that supply pumps of the central locking system are being unnecessarily exchanged. In order to correct this situation, the central locking system has to be tested. The following is a test procedure which should be performed to determine whether the supply pump needs replacing.
Procedure
1. Disconnect the 3-pole plug front the supply pump (Figure 1, arrow). Check to see that the 3-pole plug does not fit too loosely into the delivery pump, otherwise proper contact cannot be established. If necessary, rebend the female pins (e.g. with needle) in order to ensure tight contact.
2. Connect voltmeter to the 3-pole plug of the wiring harness (Figure 2 - flat part down), lock driver's door and read voltage.
Correct value: Battery voltage
3. If there is no voltage, check the fuse, wiring harness and control element in driver's door for an open circuit. Repair as necessary.
4. If voltage is available (with the driver's door locked), connect voltmeter to the 3-pole plug of the wiring harness as shown in Figure 3 (with flat part down) and read voltage.
Correct value: 0 volts
5. If voltage exceeds 0.1 volts, replace control element in driver's door.
NOTE
This type test should be repeated with the driver's door unlocked and voltmeter connected to the 3-pole plug of the wiring harness as shown in Figure 2, read voltage etc.
6. If the nominal value (0 volts) is indicated, check the central locking system for leaks (Repair Instructions 80 - 120). If necessary, eliminate leaks. If no leakage is found, replace supply pump.
Flat Rates
02-8005/01 Basic work: 0.4 hours
02 Combined work: 0.3 hours