tranny shift issue on 2003 3/4 ton w/ 5.9 cummins

My torque converter lock up feels like it is engaging and disengaging repeatedly from 40 miles an hour on up. Sometimes it does this every few seconds, sometimes it locks up for a few seconds and some times it
seems like only a split second but it never stays locked for more than 15 seconds. If I let the truck shift into O/D...it will only stay briefly as the torque convertor disengages and drops the thing into 3rd again. I tested cruise control and it drops out as well....makes sense..sort of.
The truck seems to shift properly from a stop, thru first, second and third without issue.....this only starts once I get up around 45 or so.
Chrysler service center has no idea so I took it to AAMCO......AAMCO is spending a lot of time diligently checking everything, (they've had it for a week)so far no success although they can see the pressure at the torque convertor clutch drops off to 30 PSI when the problem occurs. Someone from Chrysler said it is likely a problem with the Throttle Position Sensor but the guys at AAMCO say it doesn't have one...(not sure as I'm with them on that....can anyone tell me where it is located if it has one...and what it looks like).
Needless to say, when I'm driving, especially if I'm towing my trailer, I need to leave O/D turned off to minimize the carnage but the torque converter clutch engages and disengages every few seconds, repeatedly, for the whole trip.......up hill, on the flat, accelerating, you name it.
Any ideas anyone.
Rob
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On Jul 16, 12:26?am, snipped-for-privacy@robcoleman.ca wrote:

============================== APS signal problem
Generator creating AC noise in the DC Bus
Valve Body worn
Bad Pressure sensor on the tranny
a guess, only a guess, in case of a real emergency.......... contact a professional............
or.........remember........
google is yer friend
~:~ MarshMonster ~piss's in his coffee cup.........pours in some crownroyal.......takes a slug....... wipes the blood off his brow.......and gits back to work~ ~:~
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Yes, a faulty TPS (technically called an APPS, Accelerator Pedal Position Sensor, in that model year) is certainly in the top 5 possibilities.

That would worry me, because yes, there absolutely is one. Look on the driver's side of the engine, at the front. There will be a black plastic shroud, round at the front. Under that is the APPS - it's got two throttle cables going to it, one from the pedal in the cab, and one from the transmission, and an electrical harness. If you don't find it there, then it's located under the driver's side battery box (very late-model '03s relocated the APPS to this location).

Several. First, check the ECM ground - remove the ECM (silver box with three big connectors on it, passenger side firewall), and clean the are around the screw holes (it grounds itself through the case). You can also run a wire from the ECM mounting screw directly to the battery negative. Also check the body ground behind the passenger side battery. Again, make sure you have true metal-to-metal contact on the ground terminal. Finally, find the wire from the alternator to the passenger-side battery positive terminal, and wrap it in aluminum foil. Strange as it sounds, electrical noise from the alternator can interfere with the PCM.
With the electrical grounding/noise problems addressed, if you still have the problem, check the APPS sensor for any kind of erratic behavior (your tranny shop should be able to do this, once you show them where it's located). Check the brake switch to make sure it's not the cause of the problem.
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When wrapping this wire keep the foil away from the connectors on the ends of the wire. You don't want the foil to be energized. After wrapping the wire with foil, cover it with electrical tape. That will help keep everything in place, and it will look much nicer too.
--
Ken



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On Jul 16, 3:48 am, "Tom Lawrence"

I think I should have started here in the newsgorup rather than buggering around with the dealership and tranny shop.........thanks for all the great info....now I've got something to do tonight.
Thanks ...Rob
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On Jul 16, 10:58 am, snipped-for-privacy@gmail.com wrote:

I had the same problems with my 2000 CTD 4x4 and I did exactly what Tom and Marsh Monster told me to and it worked like a charm. The foil worked for me and I added a noise reducer inline on the APPS wire to the ECM. I got it from BD Power, around $7.00 plus s/h, takes 15 min to install.
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================== be advised.............
Tom is currently on "Yard Bird" watchlist...........
and me..........
well............
you git what you pay for
:)
~:~ mm ~sips his mushroom tea.......fires up a hooter...... mmmmmmmm.........good stuff~ ~:~
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