2008 Chevrolet Silverado 4x4 reduce engine power

Azael Diagnostician Pasadena, Texas Posted   Latest  
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Electrical
2008 Chevrolet Silverado 1500 LT 5.3L (M LH6) 4-spd (4L60-E)—3GCEK13M78G118008
P1516
C0242 - ISO/SAE Reserved
P2135 - Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation
Reduced Power

Hello fellow techs. i received this truck coming in with engine code p1516& P2135 and the vehicle would go into limp mode test signal wires at app sensor both 1 and 2 as well as tps 1 & 2 all functioned well. read tsb and saw with this code to verify software update. found truck had old software part number. recommended customer to replace tps and reflash. truck drove well for a week and came back today. customer said vehicle went back to showing limp mode :( got it back to the shop test drove it retested and all showed well, until i came back to the truck and it hesitated to start and didnt start. it was a no crank no start. so i let it sit for 30min and when i came back it started and threw p1516,p2135,c0242 and has a bad idle. looked at my 5v ref and looked at both app and tps. and now the tps signal is stuck on TPS 2 - 1.45V TPS 1 - 3.48V. even when depressing the pedal. no change. see if anyone has ran into this. also read on identifix to look for broken wires on front driveshaft but no luck

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Mark Engineer
La Junta, Colorado
Mark Default
 

Azael I have walked the same path and in the end, had to install a complete throttle body assembly (from OEM). In a few instances, after testing, before installing a throttle body assembly I was able to get by only installing a connector with pigtail wiring, a possible part number is PT-2713 or … but that is only 6-cavity connector, not sure what the 2008 needs, (although most of the…

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Azael Diagnostician
Pasadena, Texas
Azael Default
 

Did you also replace the tps with a gm one ?

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Mark Engineer
La Junta, Colorado
Mark Default
 

Azael I think I understand the question. Several years ago "when I tried to save the customer expense" I installed the TPS with OEM AC Delco, but in the end I replaced the throttle body assembly with an AC Delco throttle body (and it was complete with a new, AC Delco/OEM TPS)

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Scott Owner/Technician
Osceola, Iowa
Scott Default
 

After market tps or gm tps

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Azael Diagnostician
Pasadena, Texas
Azael Default
 

Gm

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
   

Here is how I would approach it. You said you have Identifix which means you have access to Color and OE Schematics so I am not going to post the schematic. GM will disable scan data TPS voltage live values when a TPS code is set. This is why they seem to be "stuck" there. The P2135 is for TPS 1 and 2 signals differing above a predetermined threshold for more than 2 secs. All this is also in…

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Helpful
Azael Diagnostician
Pasadena, Texas
Azael Default
 

Also I had to add that even if I clear the code the code pops right back.

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Cool so the truck is broke right now! This will be easy to find. Do you understand my post? Perform the tests I outlined and you will find it quick!! Just be sure not to touch too much or unplug something as too "fix" it before testing.

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Azael Diagnostician
Pasadena, Texas
Azael Default
 

Hey Caleb I’ve tested like you said hooking on my test lead on both 1 and 2 signal wire on the tb side and ecm side swept the throttle and both are the same. as well as wiggling the wire to see any drop outs. all is well. Also hooked up to the ground and 5 volt to see if there would be a drop

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Ok what is TPS 1 an 2 volts with blade closed? What are they with the blade all the way open?? On the scope ,not scan data.

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Keith Technician
Gretna, Louisiana
Keith Default
 

Usually, with the symptoms & codes that you have experienced, a new GM throttle body is needed. After installation, the idle relearn procedure needs to be performed using a scan tool. Just be aware that the idle relearn sometimes fails. I have had 3 occasions when it would not idle below 2000 rpms afterwards & numerous attempts were made with the factory scan tool. It was necessary to…

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Did you fix it??!!

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