Posted to Technical Tips Forum on 8/6/2009
01 Caravan PCM follies.Long post!
I had this 2001 Chrysler Voyager (!) minivan which belonged
to a non-revenue customer…(Read: My daughter's car!),
after I got the usual call all fathers are familiar
with…"Dad…my car...(fill in the blank), I am
going to bring it over to the shop". Which meant not only I
had to fix it for free and pay for the needed parts; I had
to provide a spare vehicle so she could commute to work and
also get her 7-years old daughter to school and back, for as
long as it takes!
Checking the system showed a P0204, which meant cylinder #4
was misfiring (Injector circuit open), MIL on, and the usual
shake of a dead hole. Noid light did not show any pulses,
injector was accessible and an ohm check showed 12.2 Ω
right on the money…+B to injector was present, and
driver wire to the PCM's pin 16 was not open. The engine was
of course a 3.0L.
Code cleared, and as soon as the engine started, it popped
right back on…P0204. So the conclusion by what was
obvious indicated a bad PCM…right…?!!
A rebuilt (used!) PCM from an aftermarket source was
purchased, and was programmed by the seller according to the
VIN I had submitted. It arrived, was installed, the van
started…and bingo…a miss, and P0204…again!
This time the noid light stayed on…and unburned gas
was almost pouring out of the tail pipe.
Did the same checks as before, PCM connector was
disconnected and the continuity of the driver wire was
checked again and made sure it is not open or grounded. Was
it possible the new PCM was bad also and had the same
problem? Could this be a pattern failure?! PCM was returned
and another one was on the way. (Week 2)
Enter PCM #2…!!! Same M.O., same code, and the same
misfire! Noid light on all the time…engine missing and
running rich, gas (almost) pouring out of the tail pipe!
Question: What the heck is going on?
Enter PCM #3 from another supplier…!!! But hold
on…I am not going to make the same mistake
again…or am I…?!
Is it possible the injector #4 is getting shorted after a
few quirts? So…this time we pulled the whole wiper
cowl assembly for access. We pulled the top of the intake
out, removed the injectors. All six read 12.3 Ω give
or take 0.1 or so. Hard decision, but I stopped myself
calling Linder for 6 new injectors!
We also cut the injector driver's wire a few inches away
from the PCM just to isolate the system…(of course it
was soldered later on and connected). Meanwhile I used a
test light, coming from the battery's +B , and went to the
driver's wire at the injector connector, reached behind a
few bracket, lines, tubes and such, grabbed the injector
harness's multi-connector (close to the exhaust manifold
flange!...hint…hint…), and started pulling,
pushing, yanking and twisting it like a mad man. Lo and
behold, at one instance, my test light did come ON…!!!
With a little more effort, I could just wiggle it in a
certain way and get the test light to come on consistently.
Wow…is this sucker going to ground intermittently?!
Pulled the harness out [Injector harness], and it
looked sorry. Unraveled the tape from the connector (or what
was left of the tape) [Injector harness connector] and
then saw what was causing the injector driver to go kaput!
[Damaged injector wires].
New harness could be ordered by the dealer at
$260.00…!!! So…my meticulous tech (Bob C) who is
a genius for repairing burned and distorted connectors using
any leftover crap, did a fine job repairing it
professionally using wires from a discarded Hoppy trailer
hitch connector that had come off a Dodge truck, saved for a
day that was not supposed to come…![Repaired
How this van was ever running with all of those burnt
insulation and those wires touching each other was an open a
question I never found the answer…but I did not care
The third PCM went on…the injector driver wire to the
PCM was reconnected but we used a noid light in place of
injector this time. Started the vehicle which run with a
miss, but the noid light was also flashing properly and was
not dead (like the original PCM) or staying on all the time
(like PCM's 1 and 2).
Crossing my fingers, we connected the injector #4's
connector back in…it run much smoother than I expected
and no miss. Cleared the codes again…and this baby was
Of course I did not make a claim on the PCM's (was not their
fault)…so it cost me the price of 2 PCMs and hours of
labor, headache, phone calls and frustration.
Guessing I am not the only poor sap who saw such problem on
this ubiquitous van…I hope my case helps someone if
you see unexpected PCM and injector problems down the road
on similar type of van and engine.
And I was rewarded "Thanks Dad…by the way, it needs an
oil change too…"…!!!
In my choices between punching someone or having a decent
drink…I opted for the latter!
Isn't fatherhood grand?
Mohammad from Illinois
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28 Replies Received