Electrical 389 Family
Peterbilt Motors Company 6-2
Electronic Service Agent (ESA)
Introduced in 2005, the Electronic Service Analyst (ESA) is the diagnostic software tool that is used to simplify the
troubleshooting of the new multiplexed instrumentation.
CU or CECU?
Early multiplexing in Peterbilt trucks was for the instrumentation system only. The module was known as the
Instrumentation Control Unit (ICU).
Now, as multiplexing from this control module is being used for systems other than just the instrumentation, the module
has been renamed the Cab Electronic Control Unit (CECU).
The CECU is an updated ICU. It is still located behind the center console, but now includes a few more circuits to in-
corporate the new features. ESA 2.0 is the tool for both.
Identifying which control module is in the vehicle helps determine what features are present and also aids in
troubleshooting.
Models–Build Dates Identification
TABLE 6-1. Control Module
Vehicles built with new conven-
tional interiors from April 2005 to
January 2007
365, 367, 384,
386, 387, 388,
389, 567, 579, 587
Vehicles built with EPA compli-
ant engines beginning January
2007
IDENTIFICATION
Control module identification can be made using a few methods:
Searching using the Electronic Catalog (ECAT)
Connecting using the Electronic Service Analyst (ESA) 2.0
Dome light function
ECAT IDENTIFICATION
Using ECAT or ESA 2.0 are the easiest and most exact ways of determining the type of control module in the truck.
ECAT provides a parts list “as built” and Bill of Materials in formation for each specific truck. The catalog is searchable,
and contains the part number and identification of the truck’s instrument panel control module.
ICU Part Number Q21-1029-X-XXX
CECU Part Number Q21-1055-X-XXX
