Do's and don't(s)
1. Tire Size
Automatic transmissions and transaxles are smarter than
ever, the computer takes into account the tire size to not only determine
vehicle speed but, shift timing and quality. In Front Wheel Drive vehicles
tire size is crucial to the operation of the transaxle. Two different size
tires on the front drive wheels causes a gear ratio difference inside the
transaxle. Basically one side of the differential spins faster than the
other. This causes premature wear and ultimately transaxle failure.
Different tire sizes on a vehicle include: different brand names, one tire
being older than the other, or the donut spare being run on the front too
long. Front drive tires should always be replaced at the same time. Never
mix the brands they could say on the tire that they are the same size but,
on most cases they are a little different, even tread height can be
significant enough to cause a problem! The donut spare is intended to keep
you from getting stranded! If you look in your owners manual it tells you to
go immediately to a garage to get the tire replaced. THE DONUT SPARE IS NOT
A PERMANENT FIX!
4 Wheel Drives and all wheel drives should have the same
tire size all the way around!
2. Towing
A vehicle should NEVER be towed with the drive wheels on the
ground! When the engine is not running the internals of the transmission is
not getting lubrication, basically causing the transmission to melt down. I
have seen transmissions completely melted in half due to this and can also
cause the vehicle it self to catch fire! 4Wheel and all wheel drives should
be flat bedded.
How to tell if you are experiencing transmission trouble.
1. The Check Engine Light
Hearing people come in over the years and say that a shop
told them not to worry about the check engine light makes me very
frustrated. The check engine light is your friend. its a general warning
that tells you something is wrong. The check engine light warns of more
than just engine problems it is tied into all the computers on your
vehicle. What does this mean? Any thing from the gas cap being loose to an
internal transmission failure can cause the light to come on. Computer
Diagnostics is the only way to properly diagnose a vehicle after 1990.
The Overdrive light
On some vehicles, mostly Ford, there is an Overdrive cancel
light to tell you that you are out of overdrive. However when the light
starts to blink and usually accompanied by the check engine light, it means
there is a transmission problem, and should be taken in for diagnostics
ASAP.
2. Trouble Codes
The first step in diagnostics is getting the codes that are
stored in the on-board computer that caused the check engine light or
overdrive light to blink. This is the easiest step, and one most off the
shelf scanners will do. However since there are usually more problems than
codes stored in the computer most codes have multiple meanings and the same
code can be thrown for more than one problem. Also some codes can cause
other codes to be set. This is where diagnostics gets tricky, due to just
being in the business for so long and expensive troubleshooter software you
don't se in off the shelf scanner, we have come to recognize some of the
patterns of codes thrown as a particular problem. This is not always the
case. Some vehicles my take several days to diagnose, especially when the
problem is intermittent or the computer is not detecting a problem and not
throwing a code at all. For example: when ford Manual Lever Position
Sensors(MLPS) go bad, the transmission ether quits shifting or shift hunts.
Sometimes they throw a code and sometimes not. It depends on the computer.
This is why computer diagnostics is so crucial. I have seen many times
people come in and say "I need an overhaul because my transmission won't
shift." We diagnose it and fix a $200.00 MLPS instead of a $2000-3000 dollar
overhaul.
3. Transmission Leaks
The fluid is the life blood of your transmission. The fluid
in an automatic transmission does 3 things: Lubricates, Cools and provides
hydraulic pressure. This is why the vehicle may not move when it is run low
on fluid. Transmission leaks no mater how small should be taken care of
immediately! You could damage your transmission just by running it low on
fluid once! Transmission fluid should be changed around every
20-25,000miles. Some signs of running low are: Slipping, Dropping out of
gear, Neutral at stops, No movement, Whining noise.