88M (AIT) RED BOOK PRACTICE TEST
Questions With Correct Answers (100%
Accurate) — 2026/2027.
DOMAIN 1: VEHICLE SYSTEMS, PMCS & GROUND GUIDING (14 Questions)
Question 1 (Multiple-Choice)
You are conducting PMCS on an M1088A1 tractor. The LOW AIR PRESSURE warning indicator
on the dashboard illuminates. At what primary tank pressure does this warning activate?
A) 45 PSI
B) 55 PSI
C) 65 PSI
D) 75 PSI
Correct Answer: C) 65 PSI [CORRECT]
Rationale: Per TM 9-2320-280-10 and the M1088A1 air brake system specifications, the LOW
AIR PRESSURE warning indicator illuminates when the primary air tank pressure falls below 65
PSI. This is a critical safety threshold because air brake systems require sufficient pressure
(typically 100-120 PSI normal operating range) to ensure proper brake application. At or below
65 PSI, the spring brakes may begin to engage automatically, and the vehicle must be grounded
until the air system is repaired. The operator must immediately notify the motor sergeant and
annotate the deficiency on DA Form 5988E.
Question 2 (Multiple-Choice)
During PMCS on an M1088A1 tractor, you observe the LOW AIR PRESSURE warning lamp
illuminated on the instrument panel. What is the FIRST action you must take?
A) Continue the mission and monitor the gauge every 15 minutes
B) Immediately shut down the engine and ground the vehicle
C) Drive to the nearest maintenance bay for repair
D) Increase engine RPM to build air pressure faster
,Correct Answer: B) Immediately shut down the engine and ground the vehicle [CORRECT]
Rationale: Per TM 9-2320-280-10, an illuminated LOW AIR PRESSURE warning (below 65 PSI)
indicates a critical air brake system failure. The vehicle must be immediately grounded as it is
NOT FULLY MISSION CAPABLE. The operator must not attempt to move the vehicle, as
insufficient air pressure can result in catastrophic brake failure. The deficiency must be
annotated on DA Form 5988E with a "Circle X" (critical deficiency) and reported to the motor
sergeant for corrective action.
Question 3 (True/False)
The LOW AIR PRESSURE warning indicator on the M1088A1 tractor illuminates at 75 PSI,
giving the operator ample warning before the spring brakes automatically engage at 45 PSI.
A) True
B) False
Correct Answer: B) False [CORRECT]
Rationale: Per TM 9-2320-280-10, the LOW AIR PRESSURE warning indicator on the M1088A1
illuminates at 65 PSI, not 75 PSI. The spring brakes typically begin to engage when pressure
drops to approximately 20-45 PSI (depending on the specific system configuration). The 65 PSI
threshold is the critical warning point that requires immediate operator action to ground the
vehicle. Confusing the 65 PSI warning threshold with a higher value is a common Red Book error
that can lead to unsafe operation.
Question 4 (Multiple-Choice)
On DA Form 5988E (Equipment Inspection and Maintenance Worksheet), you observe an "X"
enclosed within a circle (Ⓧ) annotated next to a brake system deficiency. What does this
"Circle X" symbol indicate?
A) A minor deficiency that can be repaired at the next scheduled maintenance
B) A maintenance item that requires ordering parts but does not affect operation
C) A critical deficiency that deadlines the equipment — the vehicle is NON-MISSION CAPABLE
D) An administrative notation for warranty tracking
Correct Answer: C) A critical deficiency that deadlines the equipment — the vehicle is NON-
MISSION CAPABLE [CORRECT]
, Rationale: Per DA Pam 738-750 and the 88M AIT Red Book doctrine, the "Circle X" (Ⓧ) is the
most severe annotation on DA Form 5988E. It signifies a critical safety deficiency that renders
the equipment "Deadlined" — meaning the vehicle cannot be operated until the fault is
corrected. Common "Circle X" deficiencies include inoperable service brakes, compromised
steering systems, or structural failures that pose immediate safety hazards. The operator must
report the deadlined status to the motor sergeant immediately, and the vehicle must be tagged
OUT OF SERVICE.
Question 5 (Multiple-Choice)
You are the driver of an HMMWV and notice the service brake pedal feels spongy. During your
pre-trip inspection, you depress the brake pedal and find it can be pushed to within 2 inches
of the floorboard. According to TM 9-2320-280-10, what is the status of this vehicle?
A) Fully Mission Capable — the pedal travel is within normal limits
B) Partially Mission Capable — requires monitoring during operation
C) Deadlined — the brake system has a critical deficiency
D) Requires only a DA Form 2404 annotation, no grounding required
Correct Answer: C) Deadlined — the brake system has a critical deficiency [CORRECT]
Rationale: Per TM 9-2320-280-10, the specific grounding criterion for the HMMWV service
brake is pedal travel. If the driver can depress the brake pedal to within 2 inches of the metal
floorboard, this indicates a severe hydraulic leak, air trapped in the system, or master cylinder
failure. This condition is NOT FULLY MISSION CAPABLE and requires a "Circle X" annotation on
DA Form 5988E. The 2-inch rule is absolute — there is no tolerance. A common Red Book error
is confusing this with a 4-inch rule (which applies to other vehicle systems). The vehicle must be
grounded immediately and reported to the motor sergeant.
Question 6 (True/False)
The "Circle X" annotation on DA Form 5988E indicates a deficiency that can be waived by the
convoy commander for a critical mission if no replacement vehicle is available.
A) True
B) False
Correct Answer: B) False [CORRECT]
Questions With Correct Answers (100%
Accurate) — 2026/2027.
DOMAIN 1: VEHICLE SYSTEMS, PMCS & GROUND GUIDING (14 Questions)
Question 1 (Multiple-Choice)
You are conducting PMCS on an M1088A1 tractor. The LOW AIR PRESSURE warning indicator
on the dashboard illuminates. At what primary tank pressure does this warning activate?
A) 45 PSI
B) 55 PSI
C) 65 PSI
D) 75 PSI
Correct Answer: C) 65 PSI [CORRECT]
Rationale: Per TM 9-2320-280-10 and the M1088A1 air brake system specifications, the LOW
AIR PRESSURE warning indicator illuminates when the primary air tank pressure falls below 65
PSI. This is a critical safety threshold because air brake systems require sufficient pressure
(typically 100-120 PSI normal operating range) to ensure proper brake application. At or below
65 PSI, the spring brakes may begin to engage automatically, and the vehicle must be grounded
until the air system is repaired. The operator must immediately notify the motor sergeant and
annotate the deficiency on DA Form 5988E.
Question 2 (Multiple-Choice)
During PMCS on an M1088A1 tractor, you observe the LOW AIR PRESSURE warning lamp
illuminated on the instrument panel. What is the FIRST action you must take?
A) Continue the mission and monitor the gauge every 15 minutes
B) Immediately shut down the engine and ground the vehicle
C) Drive to the nearest maintenance bay for repair
D) Increase engine RPM to build air pressure faster
,Correct Answer: B) Immediately shut down the engine and ground the vehicle [CORRECT]
Rationale: Per TM 9-2320-280-10, an illuminated LOW AIR PRESSURE warning (below 65 PSI)
indicates a critical air brake system failure. The vehicle must be immediately grounded as it is
NOT FULLY MISSION CAPABLE. The operator must not attempt to move the vehicle, as
insufficient air pressure can result in catastrophic brake failure. The deficiency must be
annotated on DA Form 5988E with a "Circle X" (critical deficiency) and reported to the motor
sergeant for corrective action.
Question 3 (True/False)
The LOW AIR PRESSURE warning indicator on the M1088A1 tractor illuminates at 75 PSI,
giving the operator ample warning before the spring brakes automatically engage at 45 PSI.
A) True
B) False
Correct Answer: B) False [CORRECT]
Rationale: Per TM 9-2320-280-10, the LOW AIR PRESSURE warning indicator on the M1088A1
illuminates at 65 PSI, not 75 PSI. The spring brakes typically begin to engage when pressure
drops to approximately 20-45 PSI (depending on the specific system configuration). The 65 PSI
threshold is the critical warning point that requires immediate operator action to ground the
vehicle. Confusing the 65 PSI warning threshold with a higher value is a common Red Book error
that can lead to unsafe operation.
Question 4 (Multiple-Choice)
On DA Form 5988E (Equipment Inspection and Maintenance Worksheet), you observe an "X"
enclosed within a circle (Ⓧ) annotated next to a brake system deficiency. What does this
"Circle X" symbol indicate?
A) A minor deficiency that can be repaired at the next scheduled maintenance
B) A maintenance item that requires ordering parts but does not affect operation
C) A critical deficiency that deadlines the equipment — the vehicle is NON-MISSION CAPABLE
D) An administrative notation for warranty tracking
Correct Answer: C) A critical deficiency that deadlines the equipment — the vehicle is NON-
MISSION CAPABLE [CORRECT]
, Rationale: Per DA Pam 738-750 and the 88M AIT Red Book doctrine, the "Circle X" (Ⓧ) is the
most severe annotation on DA Form 5988E. It signifies a critical safety deficiency that renders
the equipment "Deadlined" — meaning the vehicle cannot be operated until the fault is
corrected. Common "Circle X" deficiencies include inoperable service brakes, compromised
steering systems, or structural failures that pose immediate safety hazards. The operator must
report the deadlined status to the motor sergeant immediately, and the vehicle must be tagged
OUT OF SERVICE.
Question 5 (Multiple-Choice)
You are the driver of an HMMWV and notice the service brake pedal feels spongy. During your
pre-trip inspection, you depress the brake pedal and find it can be pushed to within 2 inches
of the floorboard. According to TM 9-2320-280-10, what is the status of this vehicle?
A) Fully Mission Capable — the pedal travel is within normal limits
B) Partially Mission Capable — requires monitoring during operation
C) Deadlined — the brake system has a critical deficiency
D) Requires only a DA Form 2404 annotation, no grounding required
Correct Answer: C) Deadlined — the brake system has a critical deficiency [CORRECT]
Rationale: Per TM 9-2320-280-10, the specific grounding criterion for the HMMWV service
brake is pedal travel. If the driver can depress the brake pedal to within 2 inches of the metal
floorboard, this indicates a severe hydraulic leak, air trapped in the system, or master cylinder
failure. This condition is NOT FULLY MISSION CAPABLE and requires a "Circle X" annotation on
DA Form 5988E. The 2-inch rule is absolute — there is no tolerance. A common Red Book error
is confusing this with a 4-inch rule (which applies to other vehicle systems). The vehicle must be
grounded immediately and reported to the motor sergeant.
Question 6 (True/False)
The "Circle X" annotation on DA Form 5988E indicates a deficiency that can be waived by the
convoy commander for a critical mission if no replacement vehicle is available.
A) True
B) False
Correct Answer: B) False [CORRECT]
