SOLVED: P1516 06 4.2 ls trailblazer

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
Here we go again... toooo many codes

I fixed one or before these listed... I forgot what they were though

Was getting a constant P2440 fixed that , then a p0496 just fixed that

Now I'm getting a consistent P1516 I reset the code, sit at idle for 5 minutes and the code comes right back... GGGGRRRRRRR

Prior to this new code

I already did a full tune... cleaned the Throttle Body dieletric greased all the connectors.

now the P0496 has gone away and P1516 has popped up... it's consistent.

I have read through a lot of info on it...

I'm going to check for a short in the connector... I'll check the ground on the head...

I heard about a throttle actuator and the key dilemma but no problems are evident there

Throttle body looked good when I cleaned it...

Any other suggestions before I spring for a new TB.

I got a great deal on this truck but the codes are NEVER ENDING

BTW one more thing... the truck runs GREAT no issues
 
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Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Are you also getting a Reduced Engine Power light and associated no power from the engine? This would indicate that the throttle body is not responding to the commanded opening. Maybe try disconnecting the battery for 30 minutes and while waiting, take it off and clean it. Although the cleaning procedure is not for this code, it can't hurt and will be required if the code clears up.

Edit: I just noticed you said it runs great. I still recommend you clean the TB.
 
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DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
Throttle body has been scrubbed spotless. and a relearn procedure done.

I did that when I had to remove the solenoid on the passenger side of the motor.

figured while I had it down I'd go ahead and do a tune up and a TB cleaning.

No "reduced power mode"

Battery is a fully powered optima battery. fully charging while running.

"0" indications of any ignition key symptoms.
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
Well, maybe try one more 30 minute reset. Otherwise, the TB may need to be replaced. Code says it's a performance issue so maybe it's starting to get tired but not enough to trip the REP. If you have a pick-a-part nearby, that would be a cheap option to try.
 

mrrsm

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Oct 22, 2015
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P1516 (Throttle Actuator Control Module - Throttle Actuator Position Performance)

I concur with your thinking of the possibility of having a Broken Wire in the Harness or close to the Throttle Body Connector and Harness ...perhaps within an inch or two of the Connector. The Copper Wiring in the “Drive By Wire System” is often made of the Thinnest Caliber of Solid and Braided Copper Metal the GM Engineers can get away with in order to save money on this expensive conductor.

Seldom does the idea of Harness Service R&R Hand Manipulation, years of engine vibrations or repetitive vehicle-caused-bouncing and jiggling of these harnesses look like the types of physical actions that would be enough to cause the wires to work harden, break and separate inside of the insulation… but they DO… and this presents us with an almost impossible problem that can vary whether the engine is either HOT or COLD and while constant in your present situation… not all the time in others and this is what can drive us all insane when literally trying to ‘run the wire to ground’.

The VOP (Video Original Poster) in this linked Video shows exactly where he found his problem … very close to the Throttle Body Connector. When it comes to this shared Throttle Body Design, it is important not to draw too many distinctions between any of the GM V-8 Truck Engine platforms and the GM Atlas I-6 LL8 Engines… as the principles involving the physics of this break down are identical:

http://www.engine-codes.com/p1516_chevrolet.html

...and should the P0496 (Evap Emission High Purge Flow) Code re-visit you...

https://www.autocodes.com/p0496.html

Did you mean to say that you disassembled, removed and serviced the solenoid portion and then re-assembled of the Throttle Body on the GM 4.2L Engine? How did you accomplish that?
 
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DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
I was getting a secondary air injection solenoid issue... here 's the part I forget

the code

http://www.oreillyauto.com/site/c/d...=Search_07356_1432188_2415&pt=07356&ppt=C0018

I took it apart and thoroughly cleaned it ... checked to make certain the

soleniod was working... put some kroil on the valve shaft and reassembled...

seemed to be mechanically working great ... which come to find out it was...

with the help of the forum here I found out it was actually a bad relay... relay #

55 fixed that code.

This truck is in beautiful condition but it does have 202,000 miles on it.

I believe in diagnosing not part changing. I am going to check the wiring

tonight. I found a great youtube video on the harness problem:


he also has a part 2 for repair.

Thanx inadvance everyone and I will report my progress

-=Fred=-
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
That's what happens when you post at 5am. Of course I usually recommend checking the wiring first.

I love D-Ray. He showed me how to replace the oil pump on the V8 without having to drop the pan.
 

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
well no broke wires and the code is still popping...

I also redid my ignition switch just incase that was giving the problem. It looked good.

What about this Throttle Actuator Control (TAC) module?

or just throw a new or used throttle body next?

I'm tending to go used since I'm not certain if that's the issue?

suggestions 40.00 vs 140.00?

Thanx in advance

-=Fred=-
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
If you can get a used one, I'd go that route. They're not usually a high failure rate item so getting a bad one would not be likely. And when trucks go to scrap, it's not because of a small part like this.
 
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DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
Have a used TB on order... be in by next weekend. I'll let everyone know how

it turns out.

After cleaning my current one.. any suggetsions on cleaning the new used one?

on You tube a guy said getting carb cleaner sprayed into the electronics thru

the throttle shaft made his toast?

Thank you,

-=Fred=-
 

Mooseman

Moderator
Dec 4, 2011
25,257
Ottawa, ON
I've cleaned mine multiple times, no issues. The shaft should be sealed so nothing should seep in but I'd avoid tipping it to that side.
 

AtlWrk

Member
Dec 6, 2011
674
In the meantime I would go back into the TB connector, clean both parts with electrical contact cleaner and forego the dielectric grease. These metri-pack connectors are pretty well sealed on their own and dielectric grease can cause more problems than it prevents.
 

rockp2

Member
Feb 19, 2017
2
Central PA
Here is some testing you can do on the throttle control system with a DMM (and an assistant to work the throttle in the truck):

1. TAC Motor:

a. Wait at least 15 seconds with key out of ignition

b. DISCONNECT TAC Motor connector

c. With DMM in Volts DC mode, selector switch >12 volts:

i. Backprobe YEL wire (TAC motor CNTRL 1) with DMM red lead

ii. Backprobe BRN wire (TAC motor CNTRL 2) with DMM black lead

iii. KOEO (Key On Engine Off)

iv. Voltage should be near 12v

v. Snap throttle, polarity should reverse

vi. Key OFF, reconnect TAC motor connector


2. Throttle Position Sensor:

a. With DMM in Volts DC mode, selector switch >5 volts:

b. Backprobe DK GRN wire (TPS Signal 1) with DMM red lead

c. DMM black lead to known good ground (B(-) is always optimal choice) if your lead will reach. NOTE: if any readings are below expected…check your ground, then check it again :smile:

d. Start your truck (KOER)

e. Voltage should be about 4v with throttle closed.

f. As you open the throttle you should see the voltage decrease. WOT would be close to 1v. This is where a scope would be valuable so that you could snap the throttle. Obviously don’t want to hold the throttle at WOT and not sure if your DMM would read fast enough at a snap…but you could try slow snap to see if the DMM will capture. If you have a MIN/MAX function on your DMM that may be helpful for this voltage reading

g. Move DMM test leads to:

i. Backprobe PPL wire (TPS Signal 2) with DMM red lead

ii. DMM black lead to known good ground

h. Voltage should be about 1v with throttle closed (notice this is exact opposite of TPS signal 1 test).

i. As you open throttle voltage should rise. WOT would be 3.5 – 4v (opposite of TPS signal 1 test)

j. Key off


3. APP Sensor:

a. Move to APP sensor connector above accelerator pedal (leave connected)

b. With DMM in Volts DC mode, selector switch >5 volts:

c. Backprobe DK BLU wire or DK BLU/WHT wire (APP Sensor SIGNAL 1) with DMM red lead

d. DMM black lead to known good ground

e. KOEO, voltage should increase from below 1v with accelerator pedal all the way up to above 4v with pedal all the way down

f. Move DMM red lead to backprobe LT BLU wire (APP sensor SIGNAL 2)

g. Voltage should decrease from 4v with pedal all the way up to less than 1v with pedal all the way down.

Possibly doing this test will help give you some direction to the problem.
 
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DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
Awesome information...

I cleaned the dielectric out of the connectors to no avail.

still waiting on the new TB to come in...

now I'm pulling a p0128(termostat code) along with the p1516

Man the codes never seem to cease

sheeesh

-=Fred=-
 

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
Thank you everyone for your help. I installed the new/used
Throttle Body this weekend and no more P1516

Now on to P0128 I hope and pray this will fix my last and final code... temp is showing way down. I'm going to replace the thermostat, Temp sensor and hose while I'm down doing this rediculous tedious thermostat change.
I'm going to try through the wheel well and if not I'll just pull everything and get it done.

-=Fred=-
 
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rockp2

Member
Feb 19, 2017
2
Central PA
Your thermostat is probably stuck open, but you can be sure by removing your radiator cap and having an assistant run the truck at a fast idle look for the coolant to be moving. It shouldn't move until the thermostat reaches correct opening temp. When the coolant starts moving have the assistant note the temp showing on the gauge. If the coolant is constantly moving or moving before it seems to be at correct thermostat opening temp, then you probably have a thermostat problem. If the coolant appears to moving at the correct temp, you might have an ECT sensor circuit issue and you can further diagnose. But before going through the hassle of replacing a good thermostat, you might want to check out the coolant flow as described.
 

DirtinLa

Original poster
Member
Dec 27, 2016
20
Gonzales La
Dang that's great info Rockp2...

I'll check it but I already ordered AC DELCO sensor hose and thermostat...

Perhaps I can keep them on the shelf... I'll let you know
 

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