1999 Chrysler T&C - Speed Sensor fails 2nd time in 4 month

Hi,

Just four months ago, in December I wrote about the speed
sensor problem in my 1999 T&C in this thread:
http://groups-beta.google.com/group...=IPavlov+speed+sensor&rnum=2#a0ea197303d22d9d

All the helpful advice in this group helped me then to quickly
identify and solve the problem. The sensor was replaced in
transmission repair shop and my van was back in business for
four additional month. But then, what seems to be exactly the same
problem, happened again... All the same symptoms - a little jerkiness
in transmission, limp mode again and "service engine soon" light
on again.
I'm wondering now is it that these speed sensors have such high
failure rate, that I hit it second time within a few month or
is it just my luck?
I'm also thinking: could it be the sign of some deeper problem
that causes speed sensor to fail again and again and what that
deeper problem might be? - Could it be incorrect wiring or
may be overheating of the area where the speed sensor is
located or something else?
Also, does it make sense to go to the same shop and ask them
to replace the sensor under the warranty since it is only four
month since they replaced it?

Any advice will be greatly appreciated.

IP.

 

There are 2 sensors that could cause that problem, the input and output
speed sensor, Did they replace both of them?? The output sensor always
causes the speedo to not work.
Glenn Beasley
Chrysler Tech

 

Thank you for asking the question. - It made me remember now:
First time this happened speedo didn't work, but now it is working.
Apart from this difference, everything else is the same.
So it must have been output sensor the first time and input this
time around.
Also I think they replaced only sensor that didn't work - output.
Repair cost me $72, which is probably too little for replacing the
pair of them, the price of one without labor being about $30.

Additional question: Is it typical for these sensors to break down
after certain time or mileage? The fact that they broke one after
another makes me think that it is either that or some other deeper
problem.

Thanks for you help.

 

How do you know it is the sensor again, did you have it scanned, there are
several other situations that can cause the cel and subsequent limp mode
operation.

 

You are right. - It was too early to jump to the conclusion that it
is the same sensor. In fact it looks more likely that it is an input
sensor while he first time it was the output one. - See reply by
"maxpower" in this thread.

I'll take the van to repairs Monday morning and hope this problem
will be diagnosed and fixed.
What other conditions may cause the limp mode? I guess sensors
failure is not the most serious of them.

IP.

 

I have seen these sensors go out very early, and some that just don't go
bad,I keep a set of them in my wife's 2003 Sebring just as a safety
precaution, I would check to see what the fault code is before just tossing
parts at it.

 

Yep - same sensor part numbers are used on many DC cars of the last
several years. It is well known and accepted that they fail
periodically (they are magnetic/metal sensing type sensors, and my guess
is that the magnets just gradually weaken until they cross the threshold
of working/not working - supported by the fact that they often get
intermittent/temperature/speed dependent - tranny going in and out of
limp mode several times on same trip, etc.). I know that many frequent
flyers on the 300M Enthusiasts Club keep spares in the glove
compartment. *SO*, statistically, it would not be such a strange
occurence for failures of the two sensors to occur within a couple of
months of each other (happened to me on my '99 Concorde - both times it
was a sensor - first one, then the other - I forget which was the first
to go).

FWIW, it may be that the output sensors *seem* to fail when they
actually would work again by cleaning accumulated metal particles off
the tip (the sensor sends pulses to the computer generated by the cogs
of a spline passing by it - if the sensor tip gets coated with metal
particles, it senses metal all the time so pulses don't get generated.
*BUT* for the $20-30 they cost, and the time it takes to clean one vs.
replacing one being identical, it's hardly worth trying to salvage one
that may or may not work with a cleaning - i.e., might as well replace it.

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

So where do you keep your spare ones at now Bill?

 

I don't keep spares. I walk on the wild side! 8^)

Bill Putney
(To reply by e-mail, replace the last letter of the alphabet in my
adddress with the letter 'x')

 

Thats like saying she loves me she loves me not, she loves me......etc

 

Talking of the wild-side... It really makes me weary taking
the long trips with this van - you never know when one of
these sensors will fail again. Even if I kept spare ones I
wouldn't know how to replace them. It was mentioned on this
group that it is easy, but I opened the hood and couldn't
even locate the transmission, let alone replace the sensor.
Also I noticed that when they did it in the shop they
lifted the car and did some work underneath it, so it means
the transmission is somewhere underneath, which would
probably make it hard to do this type of work while
stopping on the side of the road if it breaks down on
the long trip unless you crawl under the car.
I think it is high time for Chrysler's engineers to think
how to make their cars more reliable.

IP.

 

The sensor is under the vehicle and fairly easy to access. The sensors are
easy to find if you follow the wiring and can identify the transaxle which
is under the driver side. You carefully unclip the electrical connector,
unscrew the sensor, replace with a new one (do not overtighten as they are
plastic if memory serves correctly, and then inspect, clean if necessary and
re-attach the connector. Basically about 5-10 minutes overall provided you
can get access and have a large adjustable wrench or the correct deep
socket.

These vans are fairly dependable and even one of these sensors fail (I've
seen 3 failures in 5 different vehicles over the last 14 years), the limp
mode (2nd gear) will allow you to get it home or to a service center.

Bob