Okay...I've been through the P1516 & P2135 nightmare before and it turned out to be the TB harness - which I repaired and hadn't had a problem for a year or so. But get this...my e-brake signal switch breaks (again - I'm rough on them I guess, this is like # 5 or 6) and I pick up a new one but just don't have time to get to it right away. In order to avoid the annoying alarm, I unplug the offending switch and like clockwork the P1516 & P2135 start popping up. "No way", I think...So, I do the tug test on the TB harness again...all is well. Check the grounds (again) and double check the connections on the new Power Bastards High Amp alternator and Red Top battery...all good. Happens a few more times and then...I change the signal switch out on the e-brake pedal, plug the wire back up and poof...the codes go bye-bye. Could something that simple cause the voltage jump to set the DTCs for the TPS like that?

 

Are all the grounds connected in the stock locations? Engine harness ground connected to top right rear of block with no internal breaks in the wire? Ground strap between firewall and rear of left cylinder head? Battery to block? Ground wires to outside of frame in driver's foot area clean and intact?

 

Yep...all the grounds are good. Honestly, I ordered a spare TB just in case but since I replaced the $9 Ebrake warning switch...nada. And I've driven the cat **** out of her just to try and get a rise. I'm

 

Sounds like a possible ground issue where the ground path is now through the park brake switch and BCM. Could try running a test ground from where the park brake is mounted to the battery or block, then unplug the switch to see if it still occurs.

 

It only tripped the codes when the switch was unplugged. Could this have shorted out the ground? With the new switch in and the wire plugged back up there is no issue. Just odd...

 

Does setting the park brake cause the same codes to set?

 

Nope...only did it when I unplugged the broken switch so I woundn't have to listen to the warning chime until I switched it out.

 

Never looked at mine, but the switch might be a variable resistor, so that it only becomes an open circuit when unplugged.

Are the switches physically breaking or is it an internal failure?

 

Well, well, well...she did it to me again last night and on the way in to work this morning. This time the P2135 is paired with P0220. WTF??? I got the beast running and tugged every wire I could - starting to think the remanufactured TB is the culprit. I have a brand new spare LS3 at home I'll swap out tonight and see what happens.

 

Well...it's not the TB nor is it the TB harness. Swapped out the ported LS2 for a new LS3 and just to be sure I double checked the wiring on the harness (which I'd fixed last year) and re-did the whole process - still tossed the codes. So, I ran a circuit (ohm and V) test between the TAC and the Accelerator Pedal Position Sensor - all the wires have solid connectivity given the results of the ohm test but the required voltage to the tan wire (5.0v when the ignition is switched on) fails repeatedly. New TAC on the way...