MACS Monthly Newsletter - 2017 - JUN4

Ford Tech Service Bulletin - Blower Motor Electronic Woes from Battery Problems
Another Battery Related Ford TSB:

SSM 45789 - Some 2015-2016 Ford models including
F-150's may experience intermittent blower motor concerns
due to low battery voltage. The low battery voltage causes
the blower motor strategy to go into a start-up retry sequence every 5 seconds, then shut down completely. Cycling
the blower motor switch off and on, or cycling the ignition
switch off and on would restart the blower motor strategy.
When diagnosing intermittent or faulty blower motor concerns, first ensure the battery is in good condition using a
conductance style (i.e. Midtronics) battery tester. Then continue with normal blower motor diagnostics.

SSM 45383 - 2014 Escape - Equipped With Automatic HVAC
- Built On 1/1/2013 And Through 9/15/2014 - Various HVAC
Concerns - DTC U0164 - And/Or Intermittent Battery Drain
HVAC system symptoms may range from being totally inoperative, no communication, blower motor always on, air from
defrost only, display backlighting inoperative and may also include an intermittent battery drain which can result in a dead
battery/no crank condition. This concern may also include DTC
U0164. The drain may not be present after charging battery/
jump starting the vehicle. A revised HVAC control module
calibration is the fix for this problem. ■

Battery Drain Diagnostics - Revised and Updated!
ing a parasitic drain tool (Fig. 11) or knife switch.
With the switch in the closed position, the path for
current isn't interrupted and the vehicle can be operated in order to get the intermittent condition to
occur. When you have everything off (key off, doors
shut, etc.) you can connect your ammeter across the
switch prior to opening the switch. Since the ammeter now is in series with the battery cable, the
open switch doesn't kill B+ to the vehicle, it simply
reroutes it through the ammeter.

Photos Dave Hobbs / Special Thanks to Dick Krieger

The causes of excessive parasitic battery drains
like the one described in the previously mentioned
Ford TSB can be difficult to diagnose due to their
all too common intermittent nature. When a battery drain is small (100 mA or lower) most inductive amp clamps that are large enough to fit around
the battery cable(s) lack the resolution to accurately
measure down to parasitic load levels. That means
you often need to connect your multimeter leads in
ammeter mode in series with the battery cable us-

Figures 11 and 12: Begin with installing a parasitic draw test switch (green knob to left of meter in Fig. 11) between battery post and cable w/o disrupting B+
power (use a boost box and DLC adapter). Fuse mV voltage drop testing to determine the circuit with the excessive parasitic drain (Fig. 11) requires sharp
and clean probe tips to get a good connection (Fig. 11 magnified) for accurate testing. The 5 amp fuse on the top of Fig. 12 is the real deal with the amperage rating etched in white. The fuse below it is a knock off fuse that will not only have inaccurate readings for this particular test, it might even withstand
enough current flow (under short conditions) to melt the wiring / cause a vehicle fire before it blows. The knock offs do NOT have their amperage ratings
etched in white and have far more serrations on their plastic housings.

June 2017

MACS Service Reports

Table of Contents for the Digital Edition of MACS Monthly Newsletter - 2017