HARNESS AS-CONTROL 2915534 - Caterpillar

TECHNICAL INFORMATION BULLETIN September 27, 2005
All Cat Machines
Component Code(s) 7606SUBJECT: Product Link PL121SR (P/N 263-9088) May Remain in Power Mode 3
PROBLEM:
Some machines (especially older machines) may have minimal electrical transient suppression. As a result, the R-terminal input on the PL121SR may fail. The symptom of this failure is that the PL121SR will remain in Power Mode 3.
SOLUTION:
The R-terminal input is designed for an alternating input equal to approximately one half of system voltage or a steady state (constant) voltage, not to exceed system voltage. The R-terminal input is not designed for inductive loads, such as the coil side of a relay.
Effective with change level 04 (P/N 263-9088-04), the internal circuit of the R-terminal input has been enhanced to provide additional protection from transients.
For modules with change level 03 and below, a transient suppressor protection device (P/N 218-4935) may be installed across the input of the R-terminal and ground. This device is not polarity sensitive and may be installed in either direction. (Note: In addition to the suppressor, a plug (P/N 155-2269), two "Y" splices (P/N 207-3814) and two sealed splices (P/N 115-8109) will be required to complete the installation. Refer to Illustration 1.
Note: The addition of this suppressor is not required on all modules with change level 03 and below. This failure mode has only been seen on some older Wheel Tractor Scrapers.
Illustration 1.
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