TM 5-3805-254-20-1
ORGANIZATIONAL TROUBLESHOOTING - CONTINUED
MALFUNCTION
TEST OR INSPECTION
CORRECTIVE ACTION
42. BOTH STOP LIGHTS DO NOT WORK.
WARNING
Although KEY SWITCH must be on and battery ground cable connected to test electrical circuit
voltage, turn off KEY SWITCH and disconnect battery ground cable before doing resistance tests
or replacing parts. This will keep you from getting shocked and prevent damage to parts and
equipment.
NOTE
Scrape painted surfaces to bare metal before connecting test leads to ensure correct multimeter
readings.
Start engine and check that air pressure in air system is between 90 and 130 psi (TM 53805-254-
10). Shut down engine (TM 5-3805-254-10).
Step 1. Using multimeter, set to 20 vdc scale. Connect red test lead to terminal (1) on
stoplight switch (2) and black test lead to ground. Check for 11 to 13 vdc on
multimeter. Disconnect test leads.
a. If multimeter does not read 11 to 13 vdc, 70 wire (3) must be
replaced. Notify Direct Support Maintenance.
b. If multimeter reads 11 to 13 vdc, go to step 2.
Step 2. Using multimeter, set to 20 vdc scale. Connect red test lead to terminal (4) on
stoplight switch (2) and black test lead to ground. Push break pedal (5) down.
Check for 11 to 13 vdc on multimeter. Release brake pedal (5). Disconnect test
leads. Go to step 3.
Step 3. Test stoplight switch (2) as follows: Disconnect batteries (page 2-664). Using
multimeter, set to ohms scale and adjust to 0 ohms.
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