Bob Tom <tigers@bserv.com> wrote:
: At 07:13 PM 7/15/04, you wrote:
:> When the truck shifts into OD during a run (and you don't want
:>it to) does the "OD OFF" light go out or remain on?
: The OD lamp goes off, which would indicate to me that somehow
: another pulse signal (just as if someone had used the OD switch)
: has been sent to the pcm.
Nuts - I was hoping you'd say that it stayed on. :-) With it
going off, it could be an accidental pulse or it could be the
PCM shutting it off, so no help there. Figures it wouldn't be
the easy case. ;-)
: I've taken the OD switch out and blown compressed air into the
: end of the shift lever and also the switch itself. I've also sprayed
: some electric contact cleaner into both.
: The wire to the switch is physically open in that each end is attached
: to a separated female connector within the end of the shift lever. The
: OD pushbutton switch itself has two prongs which plug into the two
: connectors. When the button is pushed and released, the circuit
: is momentarily closed (on the push) and a pulse signal is sent to the pcm.
: For the sake of trying to put it in layman's terms, as pulse signals are sent,
: the pcm will interpret them as OD OFF and then OD ON, etc.
I assume there is enough slack in the wires to leave it hanging
off the end of the gearshift selector? If so, have you tried to
leave the button off alltogether? Perhaps attach some wire to the
stock wires to get more length if that helps at all, but basically
just touch the two female connectors together manually to turn the
OD off. (You'd have to be careful to make sure they don't touch
again during the run, obviously.) Anyway, that might help to
determine wether it is the button itself which is faulty. If you
make a bunch of runs and you don't have the problem, I guess you
could either consider yourself lucky, or the problem found. ;-) But
if it does still happen, that at least lets you know its not the
button which is doing it, and you can examine the possibility of
frayed wires. (Which you may be able to test by simply pulling
the appropriate wire out of the PCM connector, though that might
make it interesting to try to turn off the OD in the first place.) ;-)
: From a physical standpoint, I can only think of two ways that an unattended
: pulse signal can be sent. One ... the inside of the push button stays very
: close to the contacts of the two prongs when it is released and somehow
: makes contact again (vibration?) so that the circuit is closed and a signal
: is sent by itself. I don't think that is very likely just because the problem
: only occurs within a certain area of the track, the gear is in third and the
: rpm is climbing around the 5300 area. I was going to buy another switch,
: if it wasn't too expensive, just to try it. Two ... somehow the insulation
: of the wire on either end of open circuit are very close together inside the
: shift lever or steering column and has become frayed so that it will at
: times close the circuit. Again, for the same reason, I don't see if this
: highly probable. All of which lead me to try and find if the computer
: will look at other input signals and, if certain parameters are exceeded,
: put itself in OD ON "mode" (my word) and thus energize the OD solenoid.
Yep, unfortunately I think you are probably right about that.
Being how it does it with the conditions the same, it does sound
like some sort of computer intervention, and not truly random enough
for a faulty button or frayed wires. If it were one of the latter
conditions, I would expect your truck to be going into and out of
overdrive all the time, driving on the street, etc. not just that
one point on the track.
: BTW, AFAIK, the OD lamp is considered part of the OD switch but,
: not being an expert at reading wiring diagrams, I haven't figured out
: how everything is interrelated.
Yep, it used to be that the OD off button was lighted, but now
on the newer trucks, its in the gear selector lever and there is a
separate bulb. It was always two separate circuits, even with the
old method though (one path for the ground interrupt via the switch
and the other to provide voltage to the light), so I would guess
it still works the same as before, even though they are now two
physically separate devices. Possibly they are re-using the same
(or derivitave) diagrams since the circuits are still the same, just
the connection locations have changed.
: I haven't been keeping totally abreast with the BBQ but I think
: it's on the 24th (?), at the least the official part of it :-) I've got
: a points race on the 25th. I was hoping to maybe come down
: the morning of the 25th and lurk around until everyone starts
: to hit the trails but, what with my problem, I'll probably still
: busy trying to work around it.
That's understandable. :-) Hopefully I'll be able to get up
to Canada again for another meet/drag race/whatever eventually. :-)
I still have those brochures from Performance World somewhere
with a couple of events that I wanted to try to make it to. Not
sure if I'd be able to bring the cuda up or not - I was hoping to
get it dyno tuned after making the extensive engine changes (and
convert the spark over to EFI also) but maybe I'll play around
with some "mock" 1/4mi runs, and if the air/fuel seems OK maybe
I'll load it up and come up to TMP sometime and make a couple of
runs. I've been working on the car a little bit lately (stealing
time from other projects that need to get done) ;-) and have my
oil and tranny temp gauges hooked up finally. Also have a deeper
trans pan installed, and I just finished building a driveshaft
loop for it. The loop probably wouldn't satisfy an NHRA inspector,
but I have no doubt that it will do its job if required, so that
will at least remove those pole vaulting nightmares from my head. ;-)
I'm about a third of the way through making the rallye hood inserts
functional, and I just bought some sheet metal to fix some holes in
the driver's side floor pan. (Once that is done, I should be all
set to install the interior, so it can at least LOOK like a finished
car.) :-) As usual, I won't be completing anywhere near as many
items as I had hoped, but this will at least get it back on the
road so I can enjoy it until winter, hopeully drop in on a few local
cruise-ins, etc.
: To date, we've only been able to get in 5 points races because
: of the rain. My problem has me in a big hole already ... notice
: that it's never about lack of skill :-P The Street ET class points
: leader already has a 13 points lead on me ... 14 if they don't
: credit me one that I think I should have :-(
Never a lack of skill! Its an equipment failure. :-)
Now that you've got one jacket, you need to collect the whole
set! I sure hope you can get around the OD problem and rack
up some more points. Good luck! (Hey, if you like, maybe Jason
& Norah can bring back some canned mud pit to use against the
points leader?) ;-)
--
-Jon-
.-- Jon Steiger ---- jon@dakota-truck.net or jon@jonsteiger.com --.
| 1970 Barracuda - 1990 Dakota 'vert - 1992 Ram 4x4 - 1996 Dakota |
| 1996 Intruder 1400 - 1996 Kolb FireFly - 2001 Ram QC 3500 CTD |
`------------------------------------ http://www.jonsteiger.com --'
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