Pulse Generator

  • Thread starter Thread starter jmh_ottawa
  • Start date Start date
J

jmh_ottawa

I have been having problems with my auto transmission dropping into 3rd
from 4th. To correct the problem i've had to pull over switch off and back
on again. This problem generally only occured within the first 20 mins of
driving and then seemed to go away.

After having it in to the dealer they say it's the pulse generator that
needed to be replaced.
I've done 127,000km

What is the purpose of this part and what could cause it to fail?

Also, they suggest i replace my tie rod ends what would cause these to
need replacing?
 
Not sure about the pulse generator, but the tie rod ends are normal wear
items.
If I did my math right that is about 79k miles, and that's not too bad for
tie rod ends.
(I think better in English units...)
 
The pulse generators are a/c voltage generators that serve as input and
output speed sensors for your transmission. Without correct readings from
the pulse generators, the transmission computer has difficulty shifting
into the appropriate gear at the appropriate time. When this problem
occurs, the transmission computer places the transmission in fail-safe
mode (third gear only). When you turn the vehicle off and restart it, you
reset the fail-safe until the problem occurs again.

The pulse generators bolt into the transmission case. In most vehicles
1994 and newer, one bolts into the top rear of the transmission (output
speed sensor) and the other bolts into the end cover on the bottom front
(input speed sensor). They come together as a set and aren't all that
expensive. If you're able to use a socket wrench, you can purchase this
part and do the repair yourself. Just make sure to compare wire length or
use some other system to make sure you don't install the sensors in the
incorrect positions. Depending on year and model vehicle, it's possible
to reverse the locations of the sensors.
 
Yes 79k miles is right ;-)

I do about 20k miles a year ahhh the joy of living in Canada. The elantra
is a 2002 model bought new late in 2001.

I'll get them changed in the next few weeks. Thanks for the input.
 
Thanks hyundaitech.

The dealer did this for me yesterday and 100km of driving and everything
is working fine. Thank god it wasn't a tranny problem.. i know that can
get exspensive. phew.

$320 Cdn /$257 US to get this job done.

Parts were $209 cdn plus labour and taxes.
 
jmh_ottawa said:
Thanks hyundaitech.

The dealer did this for me yesterday and 100km of driving and everything
is working fine. Thank god it wasn't a tranny problem.. i know that can
get exspensive. phew.

$320 Cdn /$257 US to get this job done.

Parts were $209 cdn plus labour and taxes.
Click to expand...

This is interesting...I guess you're happy now, but I wonder what
part(S) got replaced... Can you tell us the part numbers listed on the
repair order?
 
hyundaitech said:
The pulse generators are a/c voltage generators that serve as input and
output speed sensors for your transmission. Without correct readings from
the pulse generators, the transmission computer has difficulty shifting
into the appropriate gear at the appropriate time. When this problem
occurs, the transmission computer places the transmission in fail-safe
mode (third gear only). When you turn the vehicle off and restart it, you
reset the fail-safe until the problem occurs again.
The pulse generators bolt into the transmission case. In most vehicles
1994 and newer, one bolts into the top rear of the transmission (output
speed sensor) and the other bolts into the end cover on the bottom
Click to expand...
?>front

1994 and newer...where does that come from? Hyundai did not release any
new or revised auto tranny for the MY1994 cars.
(input speed sensor). They come together as a set and aren't all
Click to expand...
that

No, not all of them come together as a set.
expensive. If you're able to use a socket wrench, you can purchase this
part and do the repair yourself. Just make sure to compare wire length or
use some other system to make sure you don't install the sensors in the
incorrect positions. Depending on year and model vehicle, it's possible
to reverse the locations of the sensors.
Click to expand...


"Hyundaitech", let me ask you this...
Do we know the pulse generators are defective on this vehicle?
 
"1994 and newer" originates from my experience as a Hyundai technician.
While you're correct that the mechanical elements of the transmission did
not change, there were computer control changes and the placement of the
pulse generators changed. It's possible this may have occurred with the
1995 model year; it's been long enough that I don't recall exactly now.
And what makes me so sure I'm right about this change? I actually
testified in a civil suit brought by a Hyundai owner against a repair
facility who installed the incorrect transmission in his vehicle. The
pulse generators were not reading the elements in the transmission that
the computer was expecting them to read, so the transmission would not
operate properly.

You're also correct, theta, that not all of them come together as a set,
but those that do not come as one piece called an input speed sensor and
another called an output speed sensor. In fact, as I learned in a later
post by the original poster which identified his year and model car, he
does not have "pulse generators" but does indeed have separate input and
output speed sensors.

And no, I don't know that a speed sensor is defective on this vehicle.
The original poster provided the information that his dealer had given him
that diagnosis. I won't be able to know whether that's correct unless he
brings his vehicle to me so I can diagnose it. But I suspect his dealer
is competent enough to diagnose this -- especially considering that the
original poster reports the problem went away after he had the work done.
 
hyundaitech said:
"1994 and newer" originates from my experience as a Hyundai technician.
While you're correct that the mechanical elements of the transmission did
not change, there were computer control changes and the placement of the
pulse generators changed. It's possible this may have occurred with the
1995 model year; it's been long enough that I don't recall exactly now.
And what makes me so sure I'm right about this change? I actually
testified in a civil suit brought by a Hyundai owner against a repair
facility who installed the incorrect transmission in his vehicle.
Click to expand...
The

Which Hyundai model?
pulse generators were not reading the elements in the transmission that
the computer was expecting them to read, so the transmission would not
operate properly.

You're also correct, theta, that not all of them come together as a set,
but those that do not come as one piece called an input speed sensor and
another called an output speed sensor. In fact, as I learned in a later
post by the original poster which identified his year and model car, he
does not have "pulse generators" but does indeed have separate input and
output speed sensors.

And no, I don't know that a speed sensor is defective on this vehicle.
The original poster provided the information that his dealer had given him
that diagnosis. I won't be able to know whether that's correct unless he
brings his vehicle to me so I can diagnose it. But I suspect his dealer
is competent enough to diagnose this -- especially considering that the
original poster reports the problem went away after he had the work
Click to expand...
done.
 
Well i'm happy that the problem seems to have gone away but still unhappy
that i had to get something like this replaced... but that's cars for
you..

The part number i had replaced seems to be this:

42620-39051 Sensor Ass.

The car i have is a 2002 Model Elantra.
 
jmh_ottawa said:
Well i'm happy that the problem seems to have gone away but still unhappy
that i had to get something like this replaced... but that's cars for
you..

The part number i had replaced seems to be this:

42620-39051 Sensor Ass.

The car i have is a 2002 Model Elantra.
Click to expand...

That's pulse generator A(input speed sensor); U.S. list price is
$66.90.
i just checked the exchange rate and it would be about 83 CDN.
dollars...
Are you sure it's the only part on the R.O.?
 
It seems to be of course it wouldn't suprise me if the parts are imported
to the us and then get taxed heavily as they pass customs into canada.

Also the dealer may be padding the price a little on the parts.. but
either way when you have problems you have to rely on the people in the
know to fix them... and that always costs.
Maybe living in the US parts are a bit cheaper who knows.
 
That's pulse generator A(input speed sensor); >U.S. list price is
$66.90.
i just checked the exchange rate and it would >be about 83 CDN.
dollars...
Are you sure it's the only part on the R.O.?
Click to expand...

I called two other local dealers and both are charging the same for that
part ($209cdn).

Perhaps the part you looked up is different or there's a load of taxes or
something being added when they are brought into canada.
 
i got 2000 accent automatic all the gears work fine.but when i put it in
reverse it feel like its in netural sometime it will go but very slow
while the engine shackes.i maintenance the trans.every 20,000 miles.use
the right fluild checked the dip stick while in netural still pink.no
small metal parts in the dip stick.an the fluild smell fine.and no nosie
or pings?? will the gears go out soon?if theres no reverse? what should i
do its the only car we have.its has 106,000 miles on it,even got the
transmission screen and pan clean.3 month back.any help thank you
 
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