MACS Service Reports - 2015 - SEP7

Fiat Chrysler Automobiles

marily for data exchange communication, as they
work primarily on C-2, the chassis and safety systems CAN bus. CAN-2 also has 120-ohm resistors
at each end, one at the ABS, the other at the ORC.
CAN-IHS (interior high speed) is the mediumhigh speed bus that covers comfort and entertainment systems. It includes the HVAC module, which
is also connected to CAN-1 so it can communicate
with the BCM and be controlled by the PCM. And
no surprise, CAN-IHS also has 120-ohm termination resistors in the BCM and the IPC (instrument
panel cluster module).
Each bus, as measured at the OBD-II plug, should
produce a 60-ohm reading with the power off and
the bus connection intact. The OBD-II plug is a good
place to start checking a data bus problem.
Because of the way they're connected in a daisy
chain, the Chrysler-recommended places for A/C
circuit diagnosis are the HVAC, ETM (entertainment/telematics module) or RRM (radio receiver
module, part of an option package or high trim level; not on all cars).
At this point Chrysler's microPOD-II is the only
communications interface between the OBD-II plug
and the wi-TECH scan tool. The VCI, even with a
smart cable, won't work. At some point in the near
future, probably when you are seeing a significant
number of these Atlantis cars in the shop, all Chrysler diagnostics (like other manufacturers) will be on
SAE J2534 Pass-Thru to meet the requirements of
the Massachusetts Right-to-Repair law. So unless
you have a strong reason to get OE tools, it pays
to wait and just invest in a full-featured J2534 tool,
which will enable you to run OE diagnostics and
reprogramming.
Atlantis also has four "LINs" (local interconnect
networks), which are basic, limited function data
busses. LIN 1 is a pass through bus that terminates
in the BCM. It is usually for the intelligent battery
sensor (temperature, voltage changes) or on some
models also for an ultrasonic anti-theft or rain sensor. LIN 2 is primarily for rear camera and on Jeeps
the terrain selector system. LIN 3 works through the
BCM to control driver and passenger window smart
motors. LIN 4, which is not connected to the BCM,
is for the steering wheel cruise control switches. ■

Figure 9: Look up from OBD-II diagnostic plug and you'll see this fuse
box, which is also the outer side of the body computer (BCM), the brain of
the new Atlantis architecture.

(Controller Area Network) data busses; 500 kbps
and one medium-speed (125 kbps) bus. We think
it's worth talking about for two reasons: 1) Chrysler is describing it as a next generation architecture,
which means that when it comes out with an allnew vehicle, that model will have Atlantis. 2) It
has significant diagnostic attributes, different from
PowerNet.
Atlantis has the body computer (BCM) as its central brain and interconnection (gateway) between
the three data busses. The BCM is under the dash
to the left of the steering wheel, and includes the
fuse box (Figure 9). It is just above the OBD-II plug.
In addition to its gateway function, it holds vehicle configuration data plus lighting, locking and
anti-theft. By comparison, PowerNet has just one
high-speed and two medium-speed CAN busses. It
uses the body computer as the gateway only for the
high-speed CAN and the medium-speed interior
CAN bus. The radio module contains the gateway
for information exchange between the telematics
bus and the interior bus.
The Atlantis C-1 CAN is primarily powertrain
and is connected to the OBD-II plug with 120-ohm
termination resistors in the PCM and BCM. As you
can see in Figure 8, the ABS and ORC (occupant restraint control) modules are on this bus, but pri-

MACS Service Reports is published monthly by the Mobile Air Conditioning Society Worldwide. It is distributed to members of MACS Worldwide
and is intended for the educational use of members of the automotive air
conditioning service and repair industry. Suggestions for articles will be
considered for publication, however, MACS Worldwide reserves the right
to choose and edit all submissions.

Editors:
Elvis Hoffpauir, Steve Schaeber
Production Designer:
Laina Casey
Manager of Service Training:
Steve Schaeber
Mobile Air Conditioning Society Worldwide
P.O. Box 88, Lansdale, PA 19446
Phone: (215) 631-7020 * Fax: (215) 631-7017
Email: membership@macsw.org * Website: www.macsw.org

Unless otherwise noted, all photos/art by author.

September 2015

MACS Service Reports

http://www.macsw.org

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