Code 1698

Our '96 T&C (184K miles) has been intermittently showing this code,
mostly in the mornings when it is cold. Driving it for a short time
causes the problem to "resolve" itself.

The transmission selector shows boxes around all gear choices (so you
cannot tell by looking at the instrument which is selected); the
speedometer does not work; the check engine light is on; the
transmission is in "limp in" mode and the scanner shows 1698 (no signal
from transmission module).

First guess: it's likely a connection issue. Is this the big connector
right below the battery box? If so, I'll open it up, inspect the
connections, clean what I can with alcohol and compressed air and put it
back together.

Unless, of course, someone has a better suggestion or another diagnosis.

Thanks in advance,

Ken

p.s. Ignore my posting "Dashboard lights hesitation" from yesterday

 

I worked on a '96 Caravan with the same symptoms that the fuse for the TCM
in the underhood box had corroded through so I swapped in the hazard light
fuse IIRC and all was well.

 

Thanks, Daniel.

I could not determine which fuse was protecting the TCM, so I took a
look at the worst looking one or two. There was some corrosion, but the
engaged portions of the contacts looked OK. I cleaned them up and stuck
them back in.

I would appreciate knowing exactly which fuse you replaced. None say
"TCM" on them.

Regards,

Ken

 

I think it was labled EATX (Electronic Automatic TransaXle) but I could be
wrong. It was a friend's van so I can't easily check to be sure.

 

Yep...that's one of the two I inspected. But, unfortunately, no go. It
is still exhibiting "morning sickness".

The interesting thing is that it is very deliberate in how it behaves
and it seems to be totally thermally induced. With an intermittent there
is a lack of stability, which this issue does not exhibit. I only have a
Chilton/Haynes type manual which shows some "typical" wiring diagrams.
I wonder if there is some type of thermal sensor that has gone bad,
either external or internal to the TCM. Also on this data bus from the
TCM is the overhead panel. When the problem occurs, certain information
there is also not updated. This suggests that the code is correct and
there is, indeed, no communications from the TCM.

Ken

 

Let me ask you: Would a "typical" highway map, say, one showing how to
get from LA to Seattle, be of any use if you were driving from, say,
Miami to Washington, D.C.? If the map from Miami to D.C. were $7, and
the one from LA to Seattle were only $0.75, would the LA-to-Seattle map
be the better buy? How is that any different than paying $15 for a
manual with "typical" schematics because it is a lot cheaper than the
$100 manual with the schematics that actually apply to your vehicle? It
might even be worth $25 for a 1-year AllData on-line subscription just
to have access to the accurate schematics right out of the FSM over your
"typical" (i.e., worthless) Haynes schematics for this one-time
immediate need.

Sorry to butt in without offering help for your problem - if it was an
LH car I might have something to offer.

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

 

Yea...I'm a cheap bastard, Bill. But think of it this way:
Ahhhhhhh....the challenge!

Actually, I took the advice of another poster years ago and glued all
the pages to one another. This, unfortunately, makes it real hard to
look anything up.

Ken

 

Ok Bill why do you have to pick on Washington DC folks?

 

Actually, max, I am in the San Francisco Bay area. We are used to being
picked on (land of fruits and nuts; left coast; etc.)

Any insights on my problem?

Thanks!

Ken

 

I was referring to myself. Anyway, you are having a bus
failure.(communication between modules) A problem like that is very tricky
to find unless it is happening at the time you are performing the test. It
could be anywhere from a module shorting out to a harness problem. A scan
tool is needed to see what modules are communicating over the bus to
diagnose this problem.What you can do is directly under the battery tray
are some connectors, access these to see what condition they are in. If
battery acid drips and eats these up it will cause this kind of problem.
That is where I would start.

Glenn

 

Much appreciated. I'll check it out.

Ken