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TK 61552-2-MM-EN
SMART REEFER 3 (SR-3) Microprocessor Controller
Refer to the SR-3 Trailer Single Temperature SL-400e, SLX/SLXe/SLXi Series Diagnostic Manual
TK 56487 for complete service information about the Microprocessor Controller and related
components.
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ntt:: A ServiceWatch download can be helpful when diagnosing a problem in a unit with
an SR-3 Controller. Therefore, it is recommended that a ServiceWatch download be
preformed to help diagnose a problem. A ServiceWatch download must be
preformed before contacting the Thermo King Service Department for assistance in
diagnosing a problem. Refer to the SR-3 Trailer Single Temperature SL-400e, SLX/
SLXe/SLXi Series Diagnostic Manual TK 56487 for information about downloading
the ServiceWatch Data Logger and viewing the data.
Fuse Link
The fuse link is located in the positive battery cable. The fuse link protects the electric system
from a short in the 2 circuit. If the fuse link burns out, check for a grounded 2 wire before
replacing the fuse link. Replace the fuse link by replacing the positive battery cable.
Air Heater
The air heater is mounted on the open end of the intake manifold. It heats the intake air to help
the engine start in cold weather. The air heater is energized by the microprocessor during
preheat, just before the engine is started.
The heater is probably defective if the resistance is more than 0.2 ohms and the current draw is
less than 60 amps, or if the current draw is more than 100 amps.
Check the resistance of the air intake heater with an ohmmeter between the M6 terminal on the
front of the heater and the screw on the back of the heater (or the heater case). The resistance
should be 0.14 ± 0.02 ohms.
Check the current draw of the heater with a clamp-on ammeter at the H1 wire near the M6
terminal on the front of the heater. During preheat the current draw should be approximately 70
amps.
Figure 11.
Air Heater
1.
M6 Terminal
Unit Wiring
Inspect the unit wiring and the wire harnesses during scheduled maintenance inspections for
loose, chafed, or broken wires to protect against unit malfunctions due to open or short circuits.
Wire Harness Routing
Do not change the factory routing of the wire harnesses inside the unit.