TM 9-6115-730-24
0013
ELECTRONIC TECHNICIAN (ET) TROUBLESHOOTING - Continued
CORRECTIVE ACTION - Continued
j.
Perform the Injector Solenoid Test at least two times.
(1) If the Injector Solenoid Test indicates OPEN for the suspect injector, the
harness under the valve cover is OK. The problem is in the windings of
the injector solenoid. Replace the injector (WP 0118). Verify that the
repair eliminates the problem.
(2) If the Injector Solenoid Test does not indicate OPEN for the suspect
injector, the problem appears to be in the engine harness under the
valve cover. Replace or repair the harness under the valve cover
(WP 0088). Run the Injector Solenoid Test in
order to
check the
installation of the new harness before installing the valve covers. Verify
that the repair eliminates the problem.
STEP 14.
If the problem is not resolved, there may be a malfunctioning cylinder that is
caused by a mechanical problem. Replace the engine (WP 0096).
SYMPTOM
6.
Speed Control Test.
System Operation Description:
The Load Sharing Module (LSM) A4 provides a throttle signal to the ECM. The output for rated speed is a pulse
width modulated (PWM) signal at a constant frequency. The speed signal varies with the position of the
FREQUENCY adjust knob. The output signal is referred to as a duty cycle or as a PWM signal. The output signal
is expressed as a percentage between 0 and 100 percent for the speed adjust. Figure 6 shows the Speed
Control Circuit.
NOTE
Desired speed can be adjusted from 1700 to 1900 rpm for a 60 Hz system and from 1400 to
1600 rpm for a 50 Hz system. The ECM calculates the desired engine rpm from the rated
speed signal and the droop signal. The rated speed signal is valid when the duty cycle is in the
range of 5 to 95 percent. If the ECM determines that the rated speed signal is invalid, the
engine rpm will be set to the programmed low idle.
MALFUNCTION
Throttle Position Signal. - Abnormal frequency, pulse width, or period.
+24 +/- 3 Vdc is not measured between terminal 15 (+) and terminal 16 (-) on the LSM A4).
CORRECTIVE ACTION
STEP 1.
Set Battery Disconnect Switch to ON. Set DEAD CRANK SWITCH to NORMAL.
On EMCP set ENGINE CONTROL switch to COOL DOWN/STOP.
STEP 2.
Measure the voltage between terminal 15 and terminal 16 on LSM A4 (Figure
FO-4, sheet 2). Connect one probe of a
voltmeter to
the +
battery terminal of
the
speed control unit. Connect the other voltmeter probe to the -battery terminal the
LSM A4.
0013-22