ACtion Magazine - NAPA - Spring 2016 - (Page 22)
A new Jeep, a new liquid line
By Paul Weissler, MACS Senior Technical Correspondent
There's a new Jeep on the market named Renegade. It's
even smaller than a Wrangler, and is the first one made
outside the United States. Although the engineering was
largely done here, including the all-wheel-drive and
four-wheel-drive systems, the new Renegade is being
made in Italy, at the factory of the parent Fiat Chrysler
Automobiles (FCA). The Renegade is sharing its basic
platform with a new Fiat, the 500X (not to be confused
with the 500 or 500L). The likely most popular engine
choice will be the Chrysler 2.4-liter Tiger Shark, but
Renegade is being made in Italy along with the corporate 1.4-liter turbocharged engine. Both of these engines
(along with a 2.0-liter four) are used in the Dodge Dart.
What is most technically novel about both the Renegade and upcoming 500X is the A/C liquid line: it's
black plastic, the first non-metallic one we've ever seen.
Also noteworthy is that the line includes the high-side
service valve, which sits on a riser at the right front of
the powertrain compartment (Figure 1).
These new models also have a new electronic architecture called Atlantis. It's an upgrade from the PowerNet introduced in 2011 and is being used on most U.S.
Figure 1: Black plastic liquid line debuts on new Jeep Renegade (and
forthcoming Fiat 500X). Riser holds the high side service valve in this
first Fiat Chrysler product line with this material application.
ACTION/NAPA * Spring 2016
built models. But as things are right now, Atlantis will
be used alongside it, and will not replace it. Somewhat
like the PowerNet, but with a different configuration.
Atlantis (Figure 2) has two high-speed CAN (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 all-new 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
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 3, the ABS and ORC (occupant restraint control)
modules are on this bus, but primarily 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 medium-high
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, CANIHS 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
Table of Contents for the Digital Edition of ACtion Magazine - NAPA - Spring 2016
ACtion Magazine - NAPA - Spring 2016
A/C Diagnostics and Troubleshooting
Staying visible in times of change
The compressor is not just a component
Restricted air flow
Externally Controlled variable displacement
A new Jeep
Increasing Facebook interactions
R-1234yf and other trends
ACtion Magazine - NAPA - Spring 2016