Throttle position sensor

[Truckie117]

Hi
Can anyone tell me if there is a throttle position sensor on a 1999 suburban, and what the part number is.

[DmaxMaverick]

Sorry. Not TPS on a 99. No external pump controls, whatsoever. There is, however, an APP. The electronic accelerator pedal.

[Truckie117]

Yes I am going to test the voltage on each circuit. Waiting for the mail to come with my GM manual. All kind of good electrical drawings and diagrams.
Does the APP go right into the pump? or is there any other in-between electrical device.
Thanks

[DmaxMaverick]

The APP does not go directly to the IP. The "in between electrical device" is the PCM.

[JohnC]

Tell us what the problem is and maybe you'll get a more useful answer...

A scanner can tell you exactly what the APP is doing. there are 3 circuits, each acts differently, and all 3 must agree or a DTC will set. If at least 2 agree you can still drive, otherwise no throttle.

[Truckie117]

Hey Guys
I originally posted this in the drive train section thinking I had a tranny problem but I dont think so!
Hi
I think I may have stated my problem wrong. What I thought was the OD dropping out is in fact a throttle problem. Tranny shifts fine but when I travel on side streets everything is fine.
When I go about 45 thats when the trouble starts truck accelerates but when I get to 60 I am hardly touching the pedal but when I try to back off the pedal truck bucks and its hard to keep steady without going faster. That is when the tranny drops out of OD like you are pressing the accelerator to pass. Going to check all the grounds and connections I have 2 new batteries and good battery connections.
Ok Today I checked the APP voltage here is what I got.

White with Black Stripe = 5volts
Tan = 5 volts
Yellow with Black Stripe = 5 volts
Dark Blue =.7 at idle
Light Blue = 4.4
Dark Green = 4.1 and goes down 3.7 when press APP
Purple = Good Ground ea checked with test light that will show ground
Brown = Good Ground
Gray = Good Ground
How do they look according to a post the light blue and dark green are out of wack anyone know if that is so?
Thanks
Mike

[DmaxMaverick]

If there's any problem, at all, with the APP, it will trigger the STS (service throttle soon) lamp. Your voltages are correct, or you'd see the lamp. The APP has 3 independent circuits. One fails, and it still works but illuminates the STS lamp. Two fail, and you have limp mode, and the STS lamp. Three fail, and nothing works, but the STS lamp. Two of the three circuits are high-to-low (starts at 5V, and decreases with increased pedal), and one is low-to-high (starts near 0, and increases with pedal). The transition should be linear and smooth. If anything APP is out o' whack, the STS visits.

Your symptoms sound more like an injection pump going/gone south.

[Truckie117]

Well I dont get it no codes truck starts up great all dash lights come on glow lights for 10 second count fire it up no problem. I can drive around the streets no problem tranny shifts ok and when I let off pedal i will slow down normally. I go above 45 and its like i dont even have to press on the pedal to keep up speed and when I let off the pedal with what little room there is it's like it is dropping to idel which causes the bucking because as soon as I touch the pedal again the truck revs up. Waiting for my manual and scan tool for computer better than the hand held device I have.
Thanks

[DmaxMaverick]

The DS pumps are generally very durable, mechanically. However, they do wear out. When they do, they get real sloppy internally, making it difficult for the electronics to compensate/stabilize the operation, and it usually happens during a specific type of operation, like coming off power to mid-idle throttle (such as would happen while cruising). Sometimes they throw codes, sometimes not. Depends on what exactly has wore out.