TM 5-2420-231-23-1
0019
Table 1. Tachometer Does Not Function or Is Inaccurate - Continued.
019
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
Test Step 3. Verify Instrument
Tachometer Does Not
Cluster Operation.
Function or Is Inaccurate -
Continued
1. Verify that the following lamps
Lamps Remain Illuminated - Proceed
remain illuminated with ignition
to step 2.
switch in the on position (TM 5-
Lamps Do Not Illuminate - Diagnose
2420-231-10) and engine not run-
the instrument cluster (WP 0018) and
ning:
then proceed to Test Step 6.
a. Low engine oil pressure
(Figure 4, Item 2)
b. Alternator (Figure 4, Item 3)
c. Parking brake (Figure 4,
Item 1)
Figure 4. Instrument Cluster Indicators.
0019
2. Start and operate engine at idle
(TM 5-2420-231-10).
Tachometer OK - Proceed to step 4.
3. Monitor and record the tachometer
reading (TM 5-2420-231-10).
Tachometer Reading Erratic or
Inconsistent - Proceed to Test Step 4.
Tachometer reading should
approximate engine speed.
Tachometer Does Not Indicate Any
RPM - Proceed to Test Step 4.
Tachometer Indicates Maximum
RPM or More - Replace instrument
cluster (WP 0177).
Proceed to Test Step 6.
4. Slowly depress foot throttle (TM 5-
Tachometer Reading Erratic or
Inconsistent - Proceed to Test Step 4.
2420-231-10). Tachometer reading
should increase smoothly with
Tachometer Does Not Indicate Any
RPM - Proceed to Test Step 4.
engine speed.
Tachometer Indicates Maximum
RPM or More - Replace instrument
cluster (WP 0177).
Proceed to Test Step 6.
