MACS Monthly Newsletter - 2020 - MAR4

Dave Hobbs

This is the process of the VIN being entered into the
TIPM. According to a write up on the "Know Your
Parts" page on the AASA (Automotive Aftermarket
Suppliers Association) website, "one method that
seems to work well, but not all the time, is to close
the hood and turn the ignition key to the "RUN"
position while waiting at least twelve seconds. The
TIPM will collect the necessary vehicle configuration and VIN data from the PCM on its own. After
twelve seconds, turn the ignition key to the "OFF"
position and then back to the "ON" position and
verify proper vehicle system operation. Of course,
the PCM and CCN (cabin compartment node, a.k.a.
instrument panel cluster) have to be in working
order for it to function properly." The technician
who shared information on the AASA website related that he had limited success with this method
because the tire ratio may not transfer over. That's
when a scan tool must be used to enter the VIN information into the replacement TIPM. While rare,
the security system PIN is lost and must be reentered after a TIPM replacement. This procedure
used to be practical until FCA dealers were told not
to share security PIN numbers with repair shops in
the independent aftermarket.
Some aftermarket scan tools have issues with
TIPM replacement requiring you to drive the vehicle, come to a complete stop, rotate the steering
wheel and press on the brakes in order to get the
ABS to sync. In some cases, you may even need a
factory scan tool (FCA Star Scan, MicroPod or J2534
with a wiTECH 2.0 subscription) to experience a
successful TIPM replacement.

Figure 7: Some aftermarket scan tools (like Auto Enginuity
shown here) can show similar information.
tool while observing a lab scope connected to the
clutch coil. Do this 20-30 times and at various temperatures. If the transistor in the TIPM is having
intermittent issues with turning on the clutch, there
might be clues on your scope as you watch its output activate the clutch over and over.

"MacGyver" Electronic Techs Out There?

There are few techs who don't mind investing in
an ESD mat (to avoid static shock damage to ICs), a
magnifying glass / microscope and a low heat soldering system for their work benches. These techs
may occasionally embark on exploratory surgery
of disassembled modules in hopes of finding that
loose solder joint. What if you find a faulty component on the disassembled TIPM's board? If you're
one of those daring techs, assuming you somehow
do find a replacement component to make the repair, you're still going to need to acquire some
precision soldering skills. The component legs are
VERY small. This is NOT a job for the 1400-watt
Weller soldering iron in your toolbox. This is assuming that the module you're attempting to repair
is not filled with the thick hard rubberized potting
(as opposed to thinner and softer conformal coating) covering the module's printed circuit boards.
Regarding the possibility of bypassing the internal
(non-serviceable) TIPM clutch relay, it does not appear to be as easy as the fuel pump bypass rewire
that many techs are performing on TIPMs. Fuel
pumps run whenever the engine runs. A/C clutches only when the driver requests cooling and when
other control modules give the go ahead for A/C
operation.

Caution Before Replacing a TIPM

As with any solid-state component responsible
for turning on outputs, make sure the output has
the correct resistance. There have been numerous
cases where a TIPM output such as an A/C clutch
coil was drawing too much current. A replacement
TIPM gets installed only to have it fail shortly after the customer leaves. Most modern electronic
modules are protected for over current conditions.
In the case of some TIPMs, this is simply not the
case according to some technicians I've spoken
with who have connected the dots with failed A/C
clutch outputs internal to the TIPM and shorted
A/C clutch coils. Remember, most clutch coils are
between 3-5 ohms. As you test the clutch in action,
why not use an ammeter with min/max settings or
watch a second channel on your lab scope display
the clutch current during your multiple clutch activation tests? At 14.5 volts the most sustained /
steady state current you measure should be under
5 amps. Always "test" to prevent making the next
TIPM "toast".

TIPM Replacements

Installing a new TIPM is straight forward wrenching (assuming certain select other original equipment modules are still on the vehicle once the replacement TIPM is powered up with ignition). Even
though technically, a replacement TIPM doesn't require programming / flashing, it does need to be
configured to the vehicle. A procedure called "Restore Vehicle Configuration" is what TIPMs require.

March 2020

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MACS Monthly Newsletter - 2020

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