MACS Monthly Newsletter - 2019 - APR8

Alldata

also need checking. But questioning the motorist
determines that he recently had the car modified to
accommodate satellite radio, which primarily consists of a special antenna. And when the antenna
was installed, it dislodged some wiring at the rear
in the trunk, and a wire in that Fuse 13 circuit eventually rubbed through to ground and caused the
problem. The no-A/C problem actually had several clues to the diagnosis: 1) trouble code pointing
to the circuit; 2) problems with other functions on
the same fused circuit; 3) relatively recent installation of an accessory. Can't ask for much more. And
yes, repairing the wire rub-through also fixed the
noted tire pressure warning system issue. Actually,
some other circuits on thaat same fuse likely were
not working properly, but because of the season
and ambient temperature were not obvious problems. ■

Figure 10: Section of A/C diagram shows only a single
wire from Fuse 13 to the high-pressure sensor, but logically there should be more.

Alldata

OE track-type) Alldata diagrams, you have to be
aware of what was done. In this specific case, there
is an A/C circuit diagram, but for the fuse that
blows (No. 13), it shows just the A/C wire, which
goes to the high-pressure sensor (Figure 10). But an
experienced technician realizes there's surely more
to that circuit, and there is, in a separate power
feed diagram (Figure 11). That brings some clarity
to the problem, for the technician also notes that
the tire pressure monitoring system is on the same
fuse, along with several other circuits, including
the back-up lamps. For other diagnostics, by the
way, there also is a separate ground circuits diagram.
The tire pressure circuit also had been misbehaving (dashboard light continuously on), so that may

Figure 11: Section of power distribution diagram covering
Fuse 13 shows all the circuits on Fuse 13, including (A)
tire pressure warning system display button; (B) air quality sensor; (C) A/C high pressure sensor; (D) automatic
dimming rear view mirror; (E) backup lamp switch; (F)
right side washer nozzle heater; (G) left nozzle heater; (H)
heater control module; (J) parking assist control module.

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 Forcey
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.

April 2019

MACS Service Reports

http://www.macsw.org

MACS Monthly Newsletter - 2019

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