MACS Service Reports - 2015 - JUN5

motorcraftservice.com

ange wire at the exposed part of the harness and
it worked, which would mean the short was somewhere in the wire from PCM No. 15 to the firewall,
before the harness went through to the Splice 213.
Much of the time a technician won't be so fortunate, and without access to splices in some of these
under-dash and under-hood harnesses, he could
end up having to cut into the conduit and look at
wires in a number of places.
One suspicion that had been raised was that perhaps the shift interlock was involved, because it's
powered off the same fuse. However, that fused
circuit output has two terminals, No. 12 for the
shift interlock, and No. 11 for HVAC, so if the fuse
didn't blow with the shift interlock operation, it
was apparently okay. See Figure 6.
Our personal preference for dealing with these
types of situations, where the circuit problem could
well be a break in the wire at or near the splice (in
this case No. 213), is to create a new splice ahead of
what you can determine is the problem area. That
is, in this case run two new wires, one from Terminal No. 9 (the temperature potentiometer circuit)
and No. 5 (the electrical part of the mode control).
Connect them with a splice under the dash, and
run a single new wire from that splice through the
firewall to the PCM's No. 15 terminal. ■

Figure 6: Shift interlock diagram shows that although the circuit also leads
from the No. 20 (10 amp) fuse, it is part of a connector with a separate
terminal (No. 12 vs. No. 11 for the A/C).

ANOTHER CASE IN THE SAME VEIN

June 2015

The only replaceable parts in the TIPM are the fuses, and
they're all good. The TIPM has working relays (non-replaceable anyway), so there must be something else wrong with
it. The technician removed it from its accessible location
(Figure 7) at the driver's side toward the front (behind the
battery) and took it apart. He saw enough corrosion (and a
burned solid state device) to convince him that this TIPM
certainly fit the pattern of a failure, so he installed a replacement, and the car was on its way. ■

techauthority.com

We periodically encounter problems that are in the same
vein but with totally different causes. Sometimes this happens on cars from the same maker. That basically demonstrates the importance of good overall diagnosis, rather than
throwing parts to cure a pattern failure. However, this example from a 2008 Jeep Patriot Sport with the 2.4-liter fourcylinder gives you a chance to head into that area, although
perhaps for a different reason.
The fan comes on when the coolant temperature goes up,
but not with A/C turned on. Separate testing with power
and ground jumper wires got both fans to spin normally. The
system was low on refrigerant, and the technician charged it
to specifications, but still no response from the fan. The highpressure side (gauges were connected) went up to about 500
psi and the pressure relief valve started to blow out refrigerant. It's pretty obvious there's a fan circuit problem.
The technician hosed down the condenser, the pressures
dropped and the system started cooling, which confirmed
that the fan circuit was the issue. He next checked for power
and ground to the relays and the TIPM (Totally Integrated
Power Module). Time for the scan tool, and the technician
was able to command both fans, through the powertrain
control module and the TIPM, although through the TIPM
only the second fan goes to high speed, vs. both fans on both
speeds via the PCM.

Figure 7: Totally Integrated Power Module on 2008 Jeep Patriot is under the hood and behind the battery, where it was subjected to corrosive
elements.

MACS Service Reports

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Table of Contents for the Digital Edition of MACS Service Reports - 2015