Inspect the flywheel for cracks or damage. It's easy now, not so much later. Pinching wire harnesses between the engine and
the transmission during reinstallation is a common mistake.
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In order to keep the bills paid, it may be time to think about adding a few tricks to your arsenal of skills. Maybe even —
gasp — transmission work.
I know, I know, most techs shudder at the thought of having to diagnose, repair and recheck something that tranny shops are
more than happy to do for them. But it's a new economic reality out there, and it may be worth keeping some of the transmission
service work in-house in order to keep revenue coming in, and only sending out the vehicles you're sure need overhaul work.
Face it: Removing a transmission on a late-model vehicle can often involve removing an entire subframe and steering rack,
and using an array of special holding and lifting tools. It's a huge endeavor, so checking carefully to see if there are other
possible causes for the problem can be a great timesaver, too.
No, that's not just a funky-looking filter. That's the control module for the 6T70 transmission. It's internal to the transmission,
inside the side pan with the fluid. The filter's a screen inside the housing , so it can't be serviced without pulling the
unit apart.
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Before condemning a tranny or sending it to a transmission shop, perform a few basic inspections first. See if the problem
can be fixed by checking for and repairing any DTCs, see if there are any published TSBs (Technical Service Bulletins), and
certainly inspect the fluid condition. Many "transmission" complaints are actually not related to the transmission at all.
They're caused by electrical problems such as wiring or component failure, or are related to module or fluid issues.
A systematic approach often can locate the cause of those problems without removing the transmission at all. That might be
a bit scary if the last transmission you had apart was in trade school, but it can be financially rewarding if you're ready
for the challenge. There are a few things to keep in mind, though, because the rules have changed, just as with every other
vehicle system. But if you're careful, you'll be fine — and possibly a bit more profitable.
Check for TSBs, DTCs, Programming Updates and Easy Fixes
After verifying the customer's complaint, the next diagnostic step — as with any other system — is checking for DTCs, TSBs
and programming updates. Here are a few examples I've run into.
One frustrated customer — after seeing two different shops for transmission work that didn't fix the concern — brought a car
to our shop to fix a "shuddering" problem on the highway. Turned out, the car had a cracked spark plug insulator that was
causing a misfire and not a transmission problem at all.
Another car was sent to the transmission shop because it wouldn't shift out of third gear. The problem turned out to be a
corroded range switch harness on the side of the transmission, which could've been repaired easily without removing any major
components.
A CHECKLIST
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Still another vehicle, a light truck, was setting transmission DTCs, which were traced to a faulty ignition switch (the wiring
diagram showed the common components) and had nothing to do with the transmission at all.
Control units are critical to transmission operation.
Sometimes controllers contain ATF monitors that must be reset (sometimes with a scan tool) after service. Sometimes the only
way to fix a problem is by updating the calibration in the controller (much easier than yanking the transmission). And often
they store DTCs that can help pinpoint the cause of the problem.
But just because transmission DTCs are present, it doesn't necessarily mean that the transmission needs to come out.
Not every transmission problem is caused by the transmission itself. Having a look at the wiring diagram after the DTCs are
read can often help solve the problem without even cracking loose a bell-housing bolt.
