Fuel Rack Position Sensor - Testing

87mercedes02

TO: OUR MERCEDES-BENZ PASSENGER CAR DEALERS

DATE: December 1987 REF.. NO.MBNA 07.1/16


SUBJECT: TESTING FUEL RACK POSITION SENSOR MODELS 124.133/.193, 126.125 AND 201.128 ENGINES 602.96 AND 603.96
In case of customer complaints regarding poor engine performance or high fuel consumption, perform the procedure outlined on page 2, observing the test conditions listed below.


Test conditions:
- Coolant temperature approx. 80~C (176~F)
- ACC system off
- Accelerator control linkage correctly adjusted

FIGURE 1:

1. Connect socket box tester to EDS control unit with test cables. Connect multimeter to sockets 3 and 11 of socket box tester (Figure 1).

FIGURE 2:

2. Disconnect boost pressure line (arrow) from aneroid compensator (103, Figure 2). Connect vacuum pressure tester to aneroid compensator (ALDA) and apply 1000 mbar of pressure.

Note: The steps to record V1 and V2 are not to last longer than 5 seconds each and there must be a two minute pause between those steps.
3. With 1000 mbar of pressure applied, start engine with selector lever in "P" and parking brake applied. Press firmly on brake pedal, place selector lever in "D". Apply full throttle for no more than 5 seconds, at 1500-2200 rpm record the voltage (V1) indicated by the multimeter. Release throttle and place selector lever in "P".

4. Disconnect boost pressure line from aneroid compensator so that the pressure line is open to atmosphere.

5. Apply parking brake. Press firmly cn brake pedal, place selector lever in "D". Apply full throttle for no more than 5 seconds, at 1500-2200 rpm record the voltage (V2) indicated by the multimeter. Release throttle and place selector lever in "P".



6. Continue with test procedure on following page.



VOLTAGE VALUES (V1 and V2)



Special Tool Information