2007 Sierra dead after tune....

MAY03LT

Member
Nov 18, 2011
3,412
Delmarva
I'm down in the sticks by seaford. Put it this way I'm so far down it takes me an hour and a half to attend our Delaware meets lol. You're welcome to stop by if you're in the area just give me a heads up.
 

littleblazer

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Jul 6, 2014
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MAY03LT said:
I'm down in the sticks by seaford. Put it this way I'm so far down it takes me an hour and a half to attend our Delaware meets lol. You're welcome to stop by if you're in the area just give me a heads up.
If my mapping is correct that puts my school smack in the middle. :undecided: I don't think he'll go for it though. I used to know a guy with a tech 2, but he works fro kia now and no longer has access to one. :rotfl: I guess I'll have to bring it to the dealer before inspection since they'll fail you for a check engine light here, all that assuming the truck runs with the new PCM. :raspberry:
 
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littleblazer

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It's ALIVE!!!!!!! (and there is no check engine light) No security relearn necessary either. :thumbsup:
 

littleblazer

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You get a cel with a case relearn right?
 

littleblazer

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Nope
 

Mounce

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Mar 29, 2014
13,667
Tuscaloosa, AL
Okay good lol. I think it sets two or three codes when it wants a case relearn.

That's a new PCM, right? Like it's not the one that came with the truck.
 

littleblazer

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Jul 6, 2014
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Yes
 

MAY03LT

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Nov 18, 2011
3,412
Delmarva
I don't have the service info for that truck and their site doesn't specify what has to be done (if anything). For peace of mind I'd axe them. :yes:
 

littleblazer

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Jul 6, 2014
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MAY03LT said:
I don't have the service info for that truck and their site doesn't specify what has to be done (if anything). For peace of mind I'd axe them. :yes:
Do you mean ask? Hehe, yea it'll probably need a case relearn though, but for now, it runs and doesn't have a cel, so it won't fail inspection automatically. Commercial vehicles need to be done every year, and its a full safety inspection. Regular passenger cars just get the gas cap and the plug in the OBD port for emissions.
 

littleblazer

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I wonder if it throws it if it detects a misfire? I think that's why it's needed for detecting misfires.
 

Mounce

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Mar 29, 2014
13,667
Tuscaloosa, AL
I'm not sure but some things take "x" amount of drive cycles before the PCM determines that there's an issue. Probably just a waiting game until it comes on.

Surprised you didn't have to do a security relearn too.
 

littleblazer

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Jul 6, 2014
9,265
Well the vin matches, that's why it's not required right?
 

littleblazer

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Jul 6, 2014
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Yea. Mark transfered as much as he could over. It runs great though. [emoji106]
 
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Mooseman

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Dec 4, 2011
25,262
Ottawa, ON
For sure the 4.2 i6 uses camshaft/crankshaft angle correlation and needs a CASE relearn when the PCM is replaced. This is due to the complexity of the VVT system and variable exhaust camshaft angles. The V8's don't have VVT and may not need such a relearn. The camshaft angle is static compared to the crankshaft.
 

littleblazer

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Mooseman said:
For sure the 4.2 i6 uses camshaft/crankshaft angle correlation and needs a CASE relearn when the PCM is replaced. This is due to the complexity of the VVT system and variable exhaust camshaft angles. The V8's don't have VVT and may not need such a relearn. The camshaft angle is static compared to the crankshaft.
We're going to go for a nice drive today and see how things settle in. I'll keep the OBD scanner on hand and monitor things. Then I'll report back. [emoji106]
 
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littleblazer

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Back to square one, dead about 40 miles from home.
 

Mooseman

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Dec 4, 2011
25,262
Ottawa, ON
Something else is definitely going on if the truck itself is killing PCMs? A really bad power surge? Or a component sending high voltage back to the PCM through a sensor wire or something? This is bizarre. This will likely need the intervention of someone with a Tech 2 and good knowledge of how to use it to diagnose this.
 
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littleblazer

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Jul 6, 2014
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A recall on the throttle body that it never went out for. Is it possible the throttle body could kill a pcm?
 

littleblazer

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To further add to the confusion, both times it happened it was the first time the pedal was put completly to the floor. So I'm really comfused.
 

Sparky

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Dec 4, 2011
12,927
WOT causes direct short in throttle body that sends power surge to PCM that fries it.

Maybe?
 

littleblazer

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Sparky said:
WOT causes direct short in throttle body that sends power surge to PCM that fries it.

Maybe?
Thats what I'm thinking, cause it happened instantly. But before the tune it was put to the floor probably ten times in the same day and never showed any symptoms of this. Does the tune command a further opening of the throttle body that may do this? Is this an unheard of incident or has this happened before. I'm really bugged by this.
 

Mounce

Member
Mar 29, 2014
13,667
Tuscaloosa, AL
Sounds pretty unheard of, to me, at least.

At this point I'd get a stock tune lol. So, how much does a throttle body for it cost? I guess if that's a known failure point then that could be it..I'm still unsure of why it would kill PCMs though.
 

littleblazer

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Jul 6, 2014
9,265
Mounce said:
Sounds pretty unheard of, to me, at least.

At this point I'd get a stock tune lol. So, how much does a throttle body for it cost? I guess if that's a known failure point then that could be it..I'm still unsure of why it would kill PCMs though.
Throttle body is 90 I believe??? Mark has his wiring guy looking into this though. I'm seriously considering going to stock.
 
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Mounce

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Mar 29, 2014
13,667
Tuscaloosa, AL
I guess give his guy some time to research things and see what they say, then decide if you wanna try tuned again or go back stock.

If you go tuned again and it kills another, I'd definitely throw in the towel and get a stock tune.

Maybe third times the charm though. :undecided:
 

littleblazer

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Jul 6, 2014
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Mounce said:
I guess give his guy some time to research things and see what they say, then decide if you wanna try tuned again or go back stock.

If you go tuned again and it kills another, I'd definitely throw in the towel and get a stock tune.

Maybe third times the charm though. :undecided:
By the time I'm done with three I could've tuned the Trailblazer twice though. Lol, I am sitting on a nice stack of cores right now.
 

littleblazer

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Jul 6, 2014
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Does anyone know what pins correspond to what to test for a short? I figure since it is throwing a throttle body code I should test it before I kill another PCM.
engine throttle.jpg
It is the 6.0l in the SS, but I would assume it is the same.
 

Mooseman

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Dec 4, 2011
25,262
Ottawa, ON
You should be able to find them by the wire colours. What code is it giving? Could be a defective pedal sensor or TB.
 

littleblazer

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u0107, a quick search shows that this code could set with a weak battery. I know optimas aren't what they used to be, but a red top from August doing this? Could it be?
 

littleblazer

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Jul 6, 2014
9,265
The only thing is the truck is still usable under that condition. I'll load test it tomorrow.
 

littleblazer

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Jul 6, 2014
9,265
It load tested bad, very bad, I'm getting about 400cca from a 800cca battery, as a control I tested my truck which has the same battery and it held right at 800cca. I may be on to something here. :undecided:
 

Sparky

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Dec 4, 2011
12,927
Never heard of a dead battery killing PCMs but hey...
 

littleblazer

Original poster
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Jul 6, 2014
9,265
Sparky said:
Never heard of a dead battery killing PCMs but hey...
Exactly, but these trucks will go into reduced engine power mode with a weak battery. I need to find a guy with a tech 2, when the pcm fault code sets, the data is stored of exactly what is happening.
 

littleblazer

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Jul 6, 2014
9,265
It's time to take it to a dealer this is way beyond me.
 

Mooseman

Moderator
Dec 4, 2011
25,262
Ottawa, ON
For that code, the low battery voltage could be causing it but I found this which has a bit more detail.

http://www.obd-codes.com/forums/viewtopic.php?f=11&t=2385

DTC U0107 sets if the battery voltage is low. If the customer's concern is slow cranking or no crank because battery voltage is low, ignore DTC U0107. Clear any DTCs from memory that may have set from the low battery voltage condition.
DTC U0107 sets when there is a short to B+ on the TAC module ground circuit. Inspect the fuses for the circuits that are in the TAC module harness-i.e. cruise, brake. An inspection of the fuses may lead you to the circuit that is shorted to the TAC module ground circuit.
DTC U0107 sets if the TAC module ignition feed circuit is shorted to a B+ supply circuit. The TAC module stays powered-up when the ignition switch is turned OFF. When the ignition switch is turned ON, the TAC module is powered-up before the PCM. DTC U0107 sets because no communication is detected by the TAC module from the PCM. Inspect related circuits for being shorted to a B+ supply circuit.
Inspect the TAC module power and ground circuits and the TAC module/PCM serial data circuits for intermittent connections.
Inspect the TAC module connectors for signs of water intrusion. If water intrusion occurs, multiple DTCs may set without any circuit or component conditions found during diagnostic testing.
When the TAC module detects a problem within the TAC system, more than one TAC system related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing an individual condition may correct more than one DTC. Remember this if you review the stored information in Capture Info.
For an intermittent condition, refer to Intermittent Conditions
 

littleblazer

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Jul 6, 2014
9,265
Thats the first time I read that, didn't come up in my searches. Will check those wires tomorrow, today was too darn cold to sit and check, and for the battery, I re checked it with load tester and it was at 750, guess I didn't make good contact the last time.
 

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