TM-9-2320-272-23-3
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 3 OF 5
SEPTEMBER 2012
TM-9-2320-272-23-3 - Page 335 of 1469
ADJUSTMENT
NOTE
•
Vehicle engine must be at normal operating temperature of 175°F to 195°F (79°C to 90°C)
as indicated by temperature gauge. Transmission oil temperature must be at normal
operating temperature of 120°F to 220°F (49°C to 104°C) as indicated by temperature
gauge.
•
Refer to TM 9-2320-272-10 for Steps (1) through (7).
1.
Allow vehicle engine and transmission to reach normal operating temperatures with transmission shift lever in
N (neutral) and parking brake set.
2.
After warmup, depress accelerator pedal until engine reaches 2,100 rpm. If engine does not reach 2,100 rpm,
troubleshoot. Proceed with testing if engine reaches 2,100 rpm.
NOTE
Assistant will operate vehicle as directed by mechanic. Mechanic will observe and record
engine rpm indicated by tachometer during shift changes.
3.
Place transmission shift lever in 1-2 (second) and road test vehicle.
4.
Accelerate at full throttle, 1,900 to 2,050 rpm, and note shift change. Record engine rpm at moment of shift
change.
5.
Stop vehicle and repeat Steps (3) and (4) in 1-3 (third).
6.
Stop vehicle and repeat Steps (3) and (4) in 1-4 (fourth).
7.
Stop vehicle and repeat Steps (3) and (4) in 1-5 (drive).
8.
Compare recorded engine rpm at shift points with correct shift point ranges given in Table 1. If all shift points
are too high or too low by approximately same amount, adjust modulator (Figure 10, Item 2).
9.
Inspect modulator (Figure 10, Item 2) and cable (Figure 10, Item 1) for looseness and improper installation.
NOTE
Modulator will be adjusted if properly installed. Refer to (WP
0365) for correct modulator and
cable installation and adjustment instructions.
10.
If looseness and/or improper installation are found, correct and retest modulator (Figure 10, Item 2) and cable
(Figure 10, Item 1).
TM 9-2320-272-23-3
0374
0374-16
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