93 Caravan Computer problem

I'm hoping someone has heard of this problem.
Drove my '93 caravan, 3.3, 4sp auto, 200K miles through a puddle and it
started misfiring. (I thought time for new wires). Next day she fired up
fine and drove fine for a week. And then it rained. She died after going
through a puddle. I believe the speedo jumped from 30 to 60MPH then bounced
down to 0, then back to normal (it does not have a speed sensor, I think
this is from the computer putting it in neutral while dieing). Then the
check engine light blinks once, then its dead. Cranks but won't start.
Went ahead and replace the wires and coil. Engine code shows code 42, Auto
Shut Down. Diagnostics computer shows crank senor good, cam sensor good,
Auto shut down "ON". Computer won't reset. Disconnect battery, won't
reset. Disconnect computer, won't reset. Disconnect/connect crank sensor,
car fires one cylinder then "ASD". Replace both crank and cam sensors with
known good sensors, fires once, then ASD. Replace the computer with a known
good one. Car starts and runs. Yea! Runs fine for 19 miles and I hit a
puddle. ASD!!!!!!! Disconnect and reconnect good computer, nothing.
disconnect/connect sensors, fires once then nothing. Take good computer
out, put bad computer in, it starts. (@#$%) Idles fine, revs up fine. put
it in gear, idles fine, hit the gas it starts bucking then ASD (more @#$%).

Three questions.
1. Has anyone heard of this? Any guesses?
2. Could it be the tranny wiring harness is getting wet? If so, does
anyone know the wire colors of the crank sensor?
3. Right after it died the last time, I heard a very faint whinny alarm
sound coming out from between the battery and the tranny. It was not coming
from the computer, the tranny computer, nor the shift control module on the
tranny. It stopped when I turn the van off and back on. Does anyone know
what this alarm is?

Thanks to all who answer.

 

The common element is water. You have an electrical problem. This is
NOT a computer problelm. Water is shorting something out.

In days gone by I have had water splashing on bad high-voltage
ignition components like plug wires and shorting out the system. In my
older cars, it caused rough running first, and then it would stall
under load.

So start with the simple stuff. remove and inspect your plug wires one
at a time. But if these are the original wires... time for a change.

Otherwise, start looking at wires and connectors. Look for worn
insulation and corroded contacts.

Good luck. Sometimes these are hard to find.

 

In my msg, I had said that I replaced the plug wires and coil. This is
not a ignition problem. I can hot wire the coil. The computer is not
sending the fire referance signal to the coil, it has also turned off
the fuel pump (solved with either or hot wiring the relay). This is
because the "COMPUTER" has tripped the "AUTOMATIC SHUT DOWN" relay
(code 42). The computer believes the engine is unsafe to start. The
purpose of the code is to shut the engine down if the timing belt
breaks. The 3.3 uses a chain and I can watch it through the cam sensor
hole and it is fine. I've also found messages from others with the ASD
/ fire once after reset problem. However the fix was never posted. In
their msgs they don't mention water. There were some referances to the
oxygen sensor. But the manuals say the ASD turns off the O2 heater not
the other way around. I do not think the problem is the water, but
the coldness of the water is pissing something off.

I took all the engine and tranny connectors apart and sprayed
electrical cleaner. I did a visual inspection of the wires where they
were visable and where they enter the connectors. However this does
not tell me if the wire has burned out inside the connector shell.
Before trying to re"pin" all 96 connector ends, 120 computer ends, and
?? sensor ends, I would prefer to chase down one set of wires. And
before cutting open the wiring harnesses to do an end to end test, I
would like to know the most likely villians (crank sensor wires?).
This also does not explain why the "$15,000 Snap-On" diagnostic
computer showed good signals on the wiring.

 

P.S.
The computer will also trip the ASD if the fuel presure drops. I have
ran a hot lead to the ASD causing it to engage which allows the fuel
pump to energize. The pump runs and has good volume. I have 3/4 tank
of gas. The hot lead also energizes the coil. I have good 12 volts
and ground on the coil. Just not the referance signal.

 

The "$15,000 Snap-On" diagnostic tool tells you what it sees. Common
sense is supposed to be supplied by the person "operating" the tool.

How many times does the PCM have to tell you that it's detected a
problem in the ASD circuits before you check those circuits out?

 

Right off the bat.... replace the ASD relay...... My van did a similar
thing.... ASD relay had gotten water in it and corroded the contacts.

Now, I dont know if the 93 has the same layout as the 94 (which is
what I have), and the ASD is in the power distribution/relay block...
unbolt it and remove the bottom and check the contacts and wires. I
checked this area on my van, and found a few wires backing out of
their terminals.

Have you cleaned the contacts in the harness that plugs into the PCM?
Try that and see if it helps.

The Snap-On scanner (weither it be a Solus, Modus, or the MT2500) can
only tell you what the PCM of the van tells it.