Engine/Transmission (1998.5 - 2002) Autopsy of an APPS

[Gary - K7GLD]

OH, I dunno - my $200 Sony does OK on closeup!

 

[Sticks]

Ever try to take a picture through a small magnifying glass?



Try it.



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[super38]

I'm the one who donated the Apps to Stiks to perform the autopsy on. This unit had about 127,000 miles on it when it failed. The symptoms included a surging while around 1700 to 2000 RPM in a lower gear (3 & 4th I don't think you could feel it in a higher gear) and the finally lose of all throttle response and codes (don't remember right now but I could look it up). Sure did hate ponying up the much cash for a poorly designed volume knob!

Thanks, Stiks for the pics



James

 

[Gary - K7GLD]

The ony other likely explanation for the physical arrangement of the fingers, would be that the resistance material they drag upon is made of a MUCH harder material than typical similar devices - tho' the significant grooves worn into the surface of that material would seem to void that theory...

 

[Sticks]

Originally posted by Gary - KJ6Q

The ony other likely explanation for the physical arrangement of the fingers, would be that the resistance material they drag upon is made of a MUCH harder material than typical similar devices - tho' the significant grooves worn into the surface of that material would seem to void that theory...

Not to mention the amount of buildup of the material on the inside of the bend.

 

[HDarga]

Sorry, but what does Apps stand for?

 

[Gary - K7GLD]

I've always been lousy at acronyms - it's sometng like Accellerator Peddle Position Sensor - or, Throttle Position Sensor - TPS - a glorified volume control that in turn connects to the Engine Control Module - ECM - to control Engine Speed - ES...

 

[Sticks]

Well I talked to a mechanic (for 10 years) and he only knows of one other vehicle that uses the "fly by wire" technology. Needless to say I am not paying much attention to his response. I will try to hit an auto parts store or three this week to see if I have any luck. I need to find one with some old crotchety fart behind the counter that hates computers and looks everything up in the catalogs.

 

[Gary - K7GLD]

OH. I think there are quite a few new 'puterized jobs running fly-by-wire - including GM vettes and camaros - dunno what exact scheme they use for control tho'...

 

[24VChev]

All the new Big Diesels (15L) are running by wire. I have a few of the Cat pedal sensors somewhere. They are only three wire units. I also have a GM 6. 5 electonic pedal lying around. I wonder if that would work.



Malcolm

 

[WadePatton]

There is a setting on my $150 camera for closeups. It is a two-position switch. Normal wide-angle is indicated by a Mountain symbol. Close-up is indicated by a Flower symbol. SEEF you can find that switch.



I got an APPS code--that's why I'm here.



Fingers installed wrong, but not easy to detect by quality control--my take.

 

[Texas Diesel]

send it to me and I'll take some pictures you wont believe then send it back to you.

 

[Sticks]

Originally posted by WadePatton

There is a setting on my $150 camera for closeups. It is a two-position switch. Normal wide-angle is indicated by a Mountain symbol. Close-up is indicated by a Flower symbol. SEEF you can find that switch.



I got an APPS code--that's why I'm here.



Fingers installed wrong, but not easy to detect by quality control--my take.

Mine is either 1 stick figure or several, it is on the single.



Tejas Deezul - Maybe later. I still need the carcass to take to some parts houses to see if I can find someone who recognizes it. So far no luck. Anyone else?

 

[Texas Diesel]

Good luck!! We're all hoping you can find the source.

 

[Sticks]

Well, I just got back from a dealer that I trust. The APPS sensor on the post 99 trucks is a star item only, and according to the service techs, it is only made for our trucks.



Not only that, it is now a restricted item, that even if you are out of warranty, or you just want to buy one, the dealer has to contact Star to get approval to order one and sell it to you. This is not a good thing.



I wonder if you could go to Radio Shack and buy a rheostat and make your own... ?



I have a contact number for DC and am going to try to find out if the damn thing is supposed to be made to scrape the contact surface, or if this is a design flaw that they do not know about. Best case scenario... RECALL and REPLACEMENT!!! Worst case scenario is I will get some outsourced company to take the calls and will just smile knowingly and nod their head ans say "We'll be in touch. "



TO BE CONTINUED...

 

[Gary - K7GLD]

"Not only that, it is now a restricted item, that even if you are out of warranty, or you just want to buy one, the dealer has to contact Star to get approval to order one and sell it to you. This is not a good thing. "



THAT is putting it mildly - sometimes, DC seems to take lessons from Ford and GM - and then screw up ROYALLY... .

 

[Gary - K7GLD]

OK, assuming that the PRIMARY point of failure on these IS the finger arrangement, not that difficult to fix - simply fabricate a new contact point that is properly designed for minimal rear, solder or otherwise attach it to the poorly designed one so it now travels on an unworn part of the carbon path, and reassemble the dern thing - and THERE'S the problem - we really need to arrive at the best and easiest way to get one apart so it CAN be repaired and reassembled, and still be usable over a decent lifespan...



We badly need some donor units to experiment on...

 

[Sticks]

Originally posted by Gary - KJ6Q

OK, assuming that the PRIMARY point of failure on these IS the finger arrangement, not that difficult to fix - simply fabricate a new contact point that is properly designed for minimal rear, solder or otherwise attach it to the poorly designed one so it now travels on an unworn part of the carbon path, and reassemble the dern thing - and THERE'S the problem - we really need to arrive at the best and easiest way to get one apart so it CAN be repaired and reassembled, and still be usable over a decent lifespan...



We badly need some donor units to experiment on...

I have to admit, that DC did one hellova job in the construction of this unit. The only way that I can see to get this thing apart is to use some star trek technology to cut the case and not remove any material from the case itself. There is no discernible seam along the outer edge that you could split it, and the housing around the top around the shaft is fairly thick, and keeps the brush assembly at a specific hight from the contact surface.



A dremmel is out of the question, as it eats too much material. The case is too thick and hard to cut with a knife or even a hot knife. One may be able to cut around the circumference with a hand saw, but there is the "removing of material" thing again.



I think our best bet is to grab one of our TDR electrical engineers to examine a functioning sensor, determine what the 6 pins do as far as the output of the sensor, and try to fab a replacement out of readily available components. It is a freakin' rheostat! How hard can this be? Damn the DC engineers.



I may go back to Cummins to see what they normally use as a throttle assembly on their engines. There has to be something that we can retrofit... for under $300... $150 would be better.

 

[Bob4x4]

Not JUST a rheostat . It also has idle validation switches



Bob

 

[Bob4x4]

If you look at the sensor it also has a small sticker,it will have the voltage value for that particular sensor. They are all close to . 5 v

but they are set to be correct for the bell crank they are attatched to... Calibrated.



Bob