December 2021 - 47

recommendation. Bill asked for my
take; I believed it looked bad and there
was a possibility that the wire could be
shorted, but the more probable cause was
that the solenoid was shorted internally
because the current indeed " ramped up "
(as inductors should).
I suggested to Bill how to confirm if
the wire was good and the solenoid was
bad. He would have to remove the wire
for the high current draw solenoid and
switch it with a known-good solenoid
wire. If the reading from the suspect solenoid
wire was good while energizing one
of the other known-good solenoids, then
the wire was not shorted. That would
prove the solenoid was the problem.
There are so many different connectors
that have different release
mechanisms and along with the dirt and
warpage, it becomes a big pain in the butt
removing wires from a connector plug.
With a bit of patience and time, Bill
successfully removed the wires from
the computer connector and switched
the bad one to a good one. He took the
wire from the high-drawing solenoid (19
amps) and moved it to another solenoid
(low-current drawing, 7.9 to 8.5 amps)
and did the reverse by installing the wire
from a proper-working solenoid and on
the high-drawing solenoid.
The results were that both the wires
were confirmed good while the highdrawing
solenoid was confirmed bad.
Understanding the circuit and using
simple logic nailed down the correct
diagnosis. The circuit that was pulling
the 19 amps was caused by a shorted
solenoid, resulting in the DTC and limp
mode. Our pinpoint test confirmed the
actual problem was the solenoid. Bill
was now confident to make the call
to the vehicle owner and explain the
problem, along with selling him the
necessary repair.
With the owner's approval, Bill
removed the valve body, ordered a new
one from the Dodge dealer, and installed
it. After the installation of the new valve
body, filter and fluid we rechecked the
current draw from the same solenoid's
circuit. We found that the new solenoid
current draw was 8.5 amps.
With the MIL extinguished and the
vehicle out of limp mode, it was time to
test drive the vehicle. After a few successful
test drives, we were confident that
the root cause of the fault was rectified
and the vehicle could be returned to
the customer.
2011 NISSAN PATHFINDER
Our next difficult vehicle was a 2011 Nissan
Pathfinder 4.0L that came in with
the customer complaint of the MIL on
and a low-power issue. After connecting
our scan tool, we uncovered one of the
most common DTCs on a Nissan vehicle,
a P0101 " Mass Air Flow Sensor Range/
Performance " . Freeze frame indicated
the following:
* 712 RPMs
* MAF= 3.5 GPS (that is under the
1 gram per liter rule on a normally
aspired engine).
After reviewing the freeze frame
information, Bill knew the next thing
he should check was the condition of
the air filter and the MAF sensor itself.
After the inspection, Bill decided to
check the actual volumetric efficiency
(VE) of the engine using the eScan
VE test. The VE test confirmed that
the MAF was underreporting, so Bill
ordered an OE replacement part from
one of our distributors.
With the new MAF installed, the VE
test was repeated and looked just about
perfect. But the MIL was still illuminated,
which would prevent the vehicle
from passing an emissions test. Bill found
that there was a TSB NTB12-051k regarding
PCM Reprogramming for MAF code
P0101. He performed the procedure that
extinguished the MIL, but there was still
a problem. With the MIL off, the vehicle
was test driven multiple times trying to
set the monitors to " Ready " only to come
up with the same issue of " Not Ready. "
With a customer who was starting to
lose faith, Bill thought that the next best
thing was to drive to the Nissan dealer
and purchase a new MAF. However, the
part number on the new Nissan part did
not match the original MAF that Bill had
already replaced. The Hitachi sensor sold
by the distributor as the OE part had a
different part number than the dealer's.
This was a first for us. With the second
new MAF installed, the vehicle was test
driven again only to report the same
results, monitors " Not Ready. " The pressure
was on and Bill had to think fast.
He contacted the Nissan hotline,
which told him to remove the battery
cables with the key off and touch the cables
together for a few minutes. This should
reset the computer back to base settings. I
always teach this very thing in my classes,
but I add an extra step for safety. I advise
connecting a 1 ohm 10-watt resistor in
series with the battery so the computer
capacitors can be drained slowly (rather
than instantaneously, possibly spiking the
computer and causing damage). Using the
resistor is a preferred method that many
OEs recommend for setting the computer
system back to the base setting.
With the procedure completed, the
three monitors that were not able to run
before (and even after a dealer MAF was
installed along with the PCM being programmed)
were finally able to run. The
OPUS IVS support line Nissan tech told
Bill that they have documented this issue
before and suggested to only use the MAF
purchased from the dealer. They suggested
verifying it is the same part as the one
being replaced.
This was a lesson learned and
one remembered. Always RTFI (read
the friggin' information) and follow
the procedure.
G. Jerry Truglia is an ASE World Class
Triple Master Technician Auto, Truck &
School Bus, L1, L3, F1, A9, X1 C1.
VehicleServicePros.com DECEMBER 2021 PROFESSIONAL TOOL & EQUIPMENT NEWS 47
http://www.VehicleServicePros.com
December 2021

Table of Contents for the Digital Edition of December 2021
