MACS Service Reports - 2016 - FEB4

a circuit and displayed the group of codes. More often, for
"economical" use of software code, a single diagnostic trouble code will cover those four failures and then you have to
sort out the actual problem.

larly with electronic modules. If the module is working at
the time, you can apply heat with a hair dryer or heat gun
to see if the failure recurs (Figure 4). If it isn't, you can try
putting it in the refrigerator to cool it. Where a module is not
easy to remove, you can cool it with an ice pack or a venturi
tool that produces cold air. A typical venturi tool which runs
on shop air can produce airflow at temperatures as low as
0°F with a flow rate of 9.0 CFM, making it suitable for spot
cooling. The ones we've seen online however are not pocket
change, priced at about $250. In the days of carburetors with
automatic chokes, there were inexpensive venturi tools for
checking chokes, although they didn't get quite as cold. ■

GM testing for intermittents and bad connections

Paul Weissler

GM has had a comprehensive program for electrical testing for some years, including the issuance of special kits you
won't find from other makers: 1) J35616 terminal test kit,
which enables a technician to probe the connectors for proper fit; 2) J42675 flat wire probe; 3) J38125 terminal repair kit.
An intermittent can be induced by movement within a
harness or connector, from vibration, engine movement
from torque (and you can get a lot if a torque strut is weak),
and from vehicle shake on rough roads. Check with a digital
multi-meter (preferably with a min-max feature so you don't
have to watch the meter to see if the circuit integrity changes. Like Ford, GM recommends: 1) wiggling the harness; 2)
pulling on the wiring to see if an intermittent is caused by a
break in the wiring inside the insulation, where you can't see
it even if you unwrap the harness covering; 3) unplugging
and reattaching a connector, which can clean off some corrosion or reestablish a poor connection in a terminal, even
if short term; 4) tugging on a connector to stress it; 5) connecting the digital multi-meter across a suspect circuit and
road-testing the vehicle.
Applying heat and cold are other test procedures, particu-

Figure 4: Use of a heat gun (shown) or hair dryer on an electronic module
might induce a heat-related failure.

THE VEHICLE'S NOT THE SAME & THERE'S A NEW HVAC OPERATING SYSTEM
Important similarities and differences in the
Nissan Rogue

The early 2014 models have had an A/C failure
(on Rogues with manual systems), and there are
three trouble codes: B24B7 for the intake air door,
B24B9 for the mode door and B24BB for the blend
air (temperature) door. There's a bulletin on the
failure, but we're not trying to put any special focus on this problem; rather, there are broader based
points to consider, and for that reason we'll set the
bulletin aside until later in this report.

Here's a problem with a couple of different wrinkles: the most basic is that you often can't rely on
what you consider long-established familiarity
with the vehicle and its HVAC, because as we'll
note, what you think is the same as previous models, is not. In this case, the Nissan Rogue compact
crossover was redone rather extensively for 2014,
but a lot of technicians will observe that it still has
the same powertrain (2.5-liter four-cylinder) and a
CVT. So there's a reason to think that it's just been
enlarged slightly and equipped with a new body.
But it wasn't. HVAC is a focus for engineering by
all makes, because of its impact on CAFE (Corporate Average Fuel Economy). In the changeover, the
A/C control system was changed, and it's so different that you can't use on 2014 models the diagnostic
techniques that would work on the previous generation of Rogues. In case you're thinking, "I haven't
had to touch a Rogue in a while and I'm unlikely to
see a two-year-old model (the 2014) for a while,"
fair enough. But seeing how a system can change
from one year to the next is important, and we're
just using the Rogue as an example.

February 2016

2014 VS. 2013
First, we'd like to point out that the control architecture for both Automatic Temperature Control and this example of a manual system outwardly
looks pretty much the same in 2013, and although
the 2014 is different, there's also a similar architecture for the ATC and manual systems.
This is not unusual. Basically, as we've reported
many times, with few exceptions the car makers
have manual systems that are electrically controlled
per the driver's selections. With an ATC system, a
bank of sensors (temperature, in-car temperature;
left and right side duct temperatures, sunload, perhaps humidity) is added to the control module wiring with computational power to integrate those inputs with the driver's settings on the control panel,

MACS Service Reports

Table of Contents for the Digital Edition of MACS Service Reports - 2016