Does anyone know what controls the shifts and torque converter lockup when
turning OD back on? My transmission does not slip or shift erratically at
all when I leave the OD button turned on. If I turn OD off and accelerate
from a stop the transmission up-shifts nicely. When I turn OD back on at
speeds at or above where it would normally shift into 4th gear, the
transmission either goes neutral or slips badly for a few seconds, then
engages again in what seems like a lower gear, then up-shifts again and acts
normally until I lock out OD again. It only happens on immediate up-shifts
when turning OD back on. It's been doing this for several years now so I
don't think it's a sign of impending doom. I don't lock out OD very often
but when I do I know to coast for a few seconds when turning it back on. I'm
going to pull the pan to adjust the bands soon and want to know if there is
something to check or adjust while the pan is off. I can wire up a manual
lockup switch or lockup signal indicator light before taking it apart if it
will help troubleshooting.
Sounds like either the solenoids are confused and not working correctly when
the mode changes, OR, the PCM gets confused. Could this be a result of
"interference" in the shift control circuit caused by the alternator wire?
The cure for this was wrapping the wire in aluminum foil or something odd
"Everyone is entitled to his own opinion, he is not entitled to his own
I thought shielding the alternator ground wire was to prevent the torque
converter from cycling in and out of lockup at cruise speeds. I'm not sure
it will help but it's easy enough to find out. The only time I have problems
is when initially turning OD back on at speeds above the normal 3-4 shift.
If I turn OD back on at speeds below the normal 3-4 shift it's fine. If I
leave OD turned on it works perfectly. If it's interference I would expect
it to happen during the normal automatic 3-4 shift as well. I'll try it and
let you know.
this is just my personal experience; I have a TC lockup switch, when I turn
on the OD with the switch "off" (50 to 55mph) I experience the same as you
are describing. with the switch "on" it shifts very fast and firm. if you go
with a lockup switch, please not the following:
the TC will not lock in 1st gear.
the Trans will NOT downshift while the switch is on. in a breaking maneuver
this helps slow down. the flip to that is the truck will not stop in safe
manner. at 25 mph the engine is at idel in 4th gear, slower than that (if
this is a Cummins) the truck will fight the breaks.
Thanks Billy. It is a Cummins. I am aware that it will stay in gear when
coming to a complete stop if the torque converter is manually locked. That's
the only reason I haven't wired a switch yet. I've been rolling the idea
around that the pulse signal from the VSS could be used somehow to disable
manual lockup at low speeds but I haven't got that ironed out yet. I believe
the VSS gives 8,000 pulses per mile so 25 mph is about 55 pulses per second.
If I can find a control circuit that switches a relay at 55 pulses per
second it would be simple to implement that as a low speed override.
What year is the truck? Have you checked for codes?
There are a couple of TSB's in the late 90's/early 00's dealing with
converters dropping out of lockup and delaying lockup due to insufficient
Your problem might be a case of the converter dropping out of lockup due to
the fluid demand caused by the engagement of the OD, this would explain the
perceived "neutral" condition as the shift event occurs. If the vehicle
speed exceeds the throttle setting when the converter unlocks it seems like
it goes into Neutral then as the OD engages and the converter delays
re-engaging it would seem like a double-shift.
It's a '99. I had it scanned today and it showed no codes.
This TSB? http://dodgeram.info/tsb/2000/21-02-00.htm
That sounds like it may be what is causing the condition. Can I replace the
separator plate myself? I've done shift kits before on C-6 automatics but
I've never done anything more than filter changes and band adjustments on
any Chrysler automatics. Will a shift kit help with this problem instead of
changing out the separator plate? Would it be a good idea to change the
separator plate and do a shift kit?
Thanks for the help.
A shift kit will necessitate opening up the valve body anyway, and would
either include a new separator plate, or would have instructions to modify
the existing plate. Either way, you'd be touching the plate.
Removal of the valve body, and the rest of the work to install the shift
kit, is very simple and straight-forward. Just keep track of which bolt
came from which hole, and pay attention to the torque specs. when
If it were me, I'd probably just go ahead and modify the stock separator
plate to open up that passage, as well as install a shift kit (might as
well - the VB's apart). And while you're at it, install a drain plug in the
pan - it will make any future fluid/filter changes a lot less messier :)
Thanks Tom. I'll look into the shift kits. I haven't had much luck with
add-on drain plugs. They always seem to leak for me. I use a vacuum tank to
pull the fluid out through the dipstick tube. It doesn't get every drop but
it keeps it from spilling all over the place when dropping the pan.
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