Table 4-2. Unit Troubleshooting Procedures (Con't).
TEST OR INSPECTION
ALL LIGHTS ON A CIRCUIT DO NOT OPERATE
When troubleshooting an electrical malfunction, ALWAYS disconnect
intervehicular cable from semitrailer. Failure to follow this warning may
create a spark and explosion, resulting in serious injury or death to
location of electrical components.
Refer to Table 4-3 to determine which lights operate off same circuit
To ensure an accurate reading, probes of multimeter must contact bare
wire and unpainted metal surfaces.
Troubleshoot tractor electrical system (see TM 9-2320-273-20 or TM 9-2320-
Check circuit across circuit breaker posts.
If there is continuity, circuit breaker is O.K. Go to step 3. If at circuit breaker #3,
#4, or #9, go to step 4.
malfunction still exists, go to step 3. If at circuit breaker #3, #4, or #9, go to
Perform step 3 if at circuit breaker #1, #2, #5, #6, #7, or #8.
Check continuity in wire between circuit breaker post and pin at front of 12-volt
If there is continuity, that wire is O.K. If at circuit breaker #1, #2, #5, or #6, go
to step 7. If at circuit breaker #7 or #8, go to step 5.
wire, visually inspect for a bent or corroded connector pin. If pin is damaged,
and if at circuit breaker #1, #2, #5, or #6, go to step 7. If at circuit breaker #7 or
#8, go to step 5.