Deep Foundation Sensor Part No

DIAGNOSIS

TEST 3 Primary speed sensor Flashing code:

4x short

Fault indication:

Fault indicated by continuously lit EDC check lamp

Fault path:

Primary speed sensor – Statically not plausible – Dynamically not plausible – Not plausible with auxiliary speed sensor

Effect of fault:

Reduced full-load quantity Reduced maximum engine speed The system switches from injection start control to control mode with fixed, specified injection start characteristics The engine is shut off by EHAB or safety relay if the auxiliary speed sensor also fails

Possible cause of fault:

Line interruption, ground short, speed sensor defective; sensor signal affected by metal shavings etc. at sensor installation position; control unit defective

Test conditions:

Terminal tester (test box) connected

Note 1:

Special features of EDC M(S) 5: Two generations of M(S) 5 systems are currently installed. The main difference between these systems is the arrangement of the speed sensors. Previously, the primary speed sensor was installed in the injection pump housing whilst the auxiliary speed sensor signal came from alternator terminal W. In the current version, the primary speed sensor and the auxiliary speed sensor are located on the flywheel housing. Primary speed sensor DG 2 (51.27120.0005) and auxiliary speed sensor DG 2 (51.27120.0006) were replaced by primary speed sensor DG 6 (51.27120.0008) and auxiliary speed sensor DG 6 (51.27120.0009). They function in the same way, although the resistance values have changed.

Note 2:

Refer to the wiring diagrams for the vehicle in question

Test

Measurement

Remedy

Resistance

Resistance measurement on terminal tester (test box) between pin 21 (+) and pin 13 (–)

− Check lines − Check plug connections − Fit a new speed sensor if no faults can be detected

Desired value: Speed sensor DG 2 on flywheel housing: 500 – 700 Ω Desired value: Speed sensor DG 6 on flywheel housing: 800 – 1000 Ω Desired value: Speed sensor in injection pump: 900 – 1300 Ω Speed signal

Signal test on terminal tester (test box) at − Check lines starting speed between pin 21 (+) and pin − Check plug connections 13 (–) using oscilloscope − Fit a new control unit if no faults can be detected Desired value: see oscilloscope curves

T 17-A1

8.40 - 5