ELECTRONIC TECHNICIAN (ET) TROUBLESHOOTING - Continued
SYMPTOM - Continued
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.
Throttle Position Signal. Abnormal frequency, pulse width, or period.
24 +/- 3 Vdc is not measured between terminal 15 (+) and terminal 16 (-) on LSM A4.
Set Battery Disconnect Switch to ON. Set DEAD CRANK SWITCH to NORMAL.
On EMCP set ENGINE CONTROL switch to COOL DOWN/STOP.
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
speed control unit. Connect one probe of the voltmeter to the -battery terminal
of LSM A4.
Measure voltage to LSM A4 (Figure FO-4, sheet 4).
a. Verify that the ground wire on terminal 16 has continuity to ground.
b. Check the voltage between engine ground and the test points listed in
Table 8. If voltage is not present at a test point, the problem is in the device,
in the wire or in the connector that precedes the point in the circuit.