Service and troubleshooting 
EST3 Installation and Service Manual  8.47 
Signature controller modules 
Substituting Signature controller modules 
When substituting a “known good” Signature controller module 
in place of a suspect rail module, you must download the system 
configuration and Signature data circuit information into the 
CPU module. This operation requires a PC and the SDU 
Program. 
The Signature controller module actually has two separate 
memories. The first memory contains the firmware that makes 
the module operate. If there is a problem with the firmware, or if 
an upgrade has been issued, the new firmware is downloaded 
into the module. When upgrading the module firmware (code), 
you do not need to download the “Bootstrap” data unless 
specifically instructed to do so. 
The SDC configuration information is stored in the module’s 
second memory. If you suspect that the module itself is bad, you 
must download the configuration information for the circuit that 
will be connected to the substitute module. 
The database must be converted before it can be downloaded 
into the Signature controller. 
 
Table 8-29: Signature controller module troubleshooting 
Problem Possible cause 
Signature Data Circuit Open  1.  Circuit incorrectly wired or connector loose 
2.  Defective detector or isolator base 
3. Broken conductor 
4.  Device not installed on circuit 
5.  Device not entered into SDU databases 
Signature Data Circuit Shorted  1.  Circuit incorrectly wired (often crossed wires on a device 
base) 
2.  Defective detector, detector base, or module 
3.  Nicked insulation between conductors 
Signature Data Circuit Ground 
Fault 
1.  Pinched wire between device and electrical box 
2.  Nicked wire insulation 
Mapping errors 
Table 8-30 provides basic information on mapping errors. For 
detailed information on identifying and locating mapping errors, 
refer to the SSDC Diagnostic and Status sections found later in 
this chapter.