TM-9-2320-272-23-1
TRUCK, 5-TON, 6X6, M939, M939A1, AND M939A2 SERIES TRUCKS (DIESEL)
TECHNICAL MANUAL; FIELD MAINTENANCE MANUAL; VOLUME 1 OF 5
SEPTEMBER 2012
TM-9-2320-272-23-1 - Page 1293 of 1313
SLOW AIR RECOVERY OR OCCASIONAL LOW AIR WARNING DURING BRAKING - Continued
STEP
5.
IS THE VOLTAGE FROM THE ECU TO THE PRESSURE SWITCH NORMAL?
a.
Refer to point to point schematics.
T0474DAA
WIRE HARNESS
PRESSURE
SWITCH
LEAD
PRESSURE
SWITCH
A
B
Figure 5.
Pressure Switch.
b.
Connect CTIS wiring harness cannon plug to ECU.
c.
Place battery switch to ON position.
d.
Place CTIS switch to ON position.
e.
Set multimeter to measure VDC.
f.
Connect multimeter red lead to pressure switch connector.
g.
Connect multimeter black lead to a known good ground.
h.
Meter reading should be greater than 23 VDC.
CONDITION/INDICATION
IS THE VOLTAGE FROM THE ECU TO THE PRESSURE SWITCH NORMAL?
DECISION
YES - Notify supervisor. It is possible that another troubleshooting work package applies.
NO - Replace ECU (Volume 5, WP
0813). Go to Step (6) to verify problem is solved.
TM 9-2320-272-23-1
0153
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