tech2

gm has released a tsb to correct the p1516 dtc.


if you are getting a p2135, gm will replace the tp sensor and update the ecm programming under a special policy for free.

2manyose442s

Hi acell84,
I finally got my 03 Sub sorted. The incidents of reduced engine power got more frequent since I last posted. Finally, 3 times in one day, but shut it off and restarted every time. A day or so later, I was in the car when it happened, took it to the dealer mech, and got a new code instead of the old 1516. The code was for the pedal position switch for the first time... Which so happened to be the very first thing I replaced, albeit with a non-GM part (O'Reilly's, and switch-only, not with pedal assembly). So this time I told the mech I would buy the GM switch, which is only available with the pedal assembly. And the problem has not come back since then (Dec 21, 2013), now going on 3 months w/o trouble. Odd, ain't it? So I spent money on new Throttle body, and the dealer mech burned more than a tank of gas (there goes Tech2's emissions savings on drive by wire) plus some amount of manhours, and the O'Reilly PPS switch goes in the spare parts pile.

Comments to tech2
There used to be a simple mechanical device to keep the throttle from "snapping shut." Called a dashpot, they worked well on mechanical linkages for many decades.
I counted about 10 firewall penetrations on my sub before I quit counting. one wire for a cable would not make much difference. And as far as noise due to holes in firewall, thats a stretch, and I would expect the mfr would do a reasonable job of sealing around this one firewall penetration as to obviate that. Otherwise we would be worried about CO or other fumes entering the cabin...
I am fine with electronic fuel injection, but it has been done (by everyone) with simple mechanical cable and torsion spring instead of the expensive and apparently difficult to diagnose DBW system.
I believe my emissions would be a lot better if alcohol was no longer put in our gas for better mileage (less gallons of fuel per mile), less corrosion damage on older vehicles, less water in the fuel.

tech2

lookit ding dong...you asked for the reasons they went to dbw. I listed them as they were explained to me in a emission training coarse; because you had no clue and asked to know. I didn't come up with them. If you think they are not valid, take it up with an engineer. If you have better explainations as to why they went to dbw I'd love to hear it....then after your post I can tell you why they make no sense...sound about right.

While your at it:
Maybe you can explain why they haven't used dashpots since the eighties.


Please elaborate on how your emissions would be better without ethanol blended into gasoline.

acell84

Ok that makes sense.. around how much did that cost to get switched over? Dealer service fees are ridiculous

EN83

I had this problem(going a month now without p1516), all I've done includes replace / clean all the ground wires & connections(still got code), tried different TAC & Pedal sensor(still got code), replaced the pigtail(still got the code), ran new wires(harness from TAC to TB and still had code), new TB(cardone aftermarket still had code), used the original TB with a new TPS(amazon sells them ) and finally that fixed it, im assuming the cardone TB was binding somewhere, so I'd go with delco parts all the way, cant say this will fix your problem or not BUT so far I haven't missed a beat. and that's with paying GM to do a bunch of tinkering including updating the trucks software. its a big PITA but if you enjoy your vehicle like I do - its well worth it. just my two cents, good luck!
Ed




this is the one I actually bought:

acell84

Ok thanks. Here's the million dollar question that I'm sure most have thought of..WHY THE HELL ISN'T THERE A RECALL?? If this is a huge problem with multiple vehicles, then why

Pugly

dashpots were there to reduce emissions believe it or not - if the throttle snapped shut closing off all the incoming air the HC would take a huge rise - these days they shut down injectors and use IAC motors to control that

tech2

iac stepper motors have gone the way of the dashpot also...extinct.


feedback carburetors needed so many add ons just to operate and they did so poorly. todays dbw systems are very accurate and do a much better job controlling emissions. they also eliminate the need for iac and cruise control stepper motors. gm is currently correcting the tp sensor problems under warranty and then this issue will be resolved.

'03 Heavy Chevy

When my truck started throwing the P1516 code, it was also throwing the knock sensor codes P0332 (for the rear sensor) and P0327 (for the front sensor).
I ended up having to change both knock sensors and the throttle body

Hampstar7

That is not the case, I got fed up with my truck and finally took it in to the dealer. 633 bucks later, They replaced the throttle body and updated/reprogrammed the ECM