Buzzing noise in throttle body

[fdryer]

It won't hurt whether electronic contact cleaner is used or not.

[Cmarie3387]

Okay so we did as was suggested now we disconnected negative battery. And disconnected the ecm. It did start. It does say “reduced power” the check engine light and the service light is on....no pins are bent at all.

[fdryer]

Ooh, those two multiple pin terminals are scary looking. Not only male pins but female sockets. Careful attention to details when disconnecting, ensuring male and female terminals aren't folded, bent or broken. Females hide their terminals behind the plastic connector body and difficult to determine whether they're forked or round terminals. The simple disconnect and reconnect tends to force them to wipe each other of any oxidation that can hinder low voltage signals. Thankfully, the electrical engineers knew in predicting long term weathering effects to use copper or gold plating to resist oxidation in vehicle electrical connections. Brass is another metal resistant to oxidation. With the reduced power and check engine lights turned on, this may be a direct result of new problems or continuing with the original mystery related to ecm connections. I'm not sure what's occurring and expect a new round of error codes but the wrench light may not be decoded by generic code readers. Wrench codes are specific to each manufacturer - GM may use (say) P01234 to mean the front headlights need cleaning while Ford may state the trunk toilet needs to be emptied. Manufacturer specific wrench codes are unique to each manufacturer and requires a better reader or scantool. Maybe your reader can decode both check engine and wrench light codes and maybe only the check engine light codes. My (at the time expensive) reader only reads check engine light stored codes. When the wrench light turned on, nada/zilch/zero code(s) displayed. They eventually went away and my guess was related to xmission codes. My recent purchase of an aftermarket reader read stored history codes and displayed a few. One was for a xmission pressure control solenoid error and another for bcm error. I kinda knew the tcm and bcm tried telling me they both had errors to display but they went away and never came back. My interest in a new reader was prompted by two things; desire to know if stored history codes can be displayed at any time and what they pointed to. I was also able to program two remotes too with my new toy so it justified the cost to buy a reader to read almost every code in the GM family that isn't read by generic readers. You can try AutoZone or other stores in hopes of finding better readers but don't rely on them. AutoZone upgraded their readers so they can decode abs errors. Before that, their readers couldn't. As more vehicles age and more problems pop up, the demand is there to have more reader capability. Abs error codes can be read and displayed with AutoZone's readers but not wrench codes, yet.

Reduced power mode restricts engine power to around 15% so at least the engine starts up. You won't be doing any stoplight racing or trying to enter highway ramps yet. The next questions are what codes are stored to determine which way to go. Sometimes, just sometimes, some errors correct themselves as the engine runs as the ecm relearns what it missed and tries to start somewhere in its programs. Power disconnects don't disturb programmed memory but does erase short term memory like emissions parameters continuously updated as engines run. Erasing parameters simply forces the ecm to start with factory defaults and learn as the engine is used in the next few days. This doesn't explain reduced power mode. RPM is directly related to four things; pedal, throttle, ecm and wiring among them.

[Cmarie3387]

I appreciate your input. It all seems to be related to the ecm the computer. So upon being exhausted from this situation and time ticking as the car just is recently insured I don’t want to waste too much time searching. All the codes that I put on here was relating to the ecm. Now, when I bought the car I took it on a 10-15 min test drive there was no check engine light on at the time. So I’m coming to a conclusion that when my boyfriend did the valve cover gaskets the ecm was in the way at some point he said he didn’t fully but somewhat loosened one of the ecm cords. This is probably was caused the issue and possibly was on its way out anyways. I did however purchase today a 100% refurbished ecm from flag ship one it’s being shipped and should receive the part shortly bought it for $150. I believe once the “new” ecm is replaced the car will run perfectly again and we both think it’s something within the ecm that isn’t working properly. Will post on the final update once the new ecm is placed in the car also I know we have to do a pass lock with the new replacement

[Cmarie3387]

So my boyfriend put in the new pcm. He did the-programming with the key l. Now I’m not with him and he only gave me a brief description but it still says reduced power mode! Honestly This car is stressing me out beyond belief. He started but it’s saying it’s reduced power..why?!? It’s a new refurbished pcm I’m assuming he connected everything back properly..what could be the issue?

[Cmarie3387]

Also, he said that tomorrow he will clear the codes to see if that will fix the issue..if replacing a whole new pcm to the car why would reduced power mode still be on?

[02 LW300]

I do have a factory service manual set for a 2002. So please post all current codes and I will try to help.
Andy

[Cmarie3387]

Okay Andy I will plug it in tomorrow and let you know what pops up..but will replacing a pcm I don’t understand as to why it still says reduced power mode? I hope nothing else needs to be replaced.

[02 LW300]

The codes should guide us to a solution. At least it runs now, that eliminates a lot of components that could be bad.

[fdryer]

Well, with a different ecm and initial startup returning reduced power mode, doesn't this narrow the problem to wiring, throttle and pedal?

[02 LW300]

Probably but codes should tell the tale.

[Cmarie3387]

I am going to check the codes today and get back to you

[Cmarie3387]

Okay coded are u2105, p0452, p0102, p0128, p0050, p1523, p1780, p1516. This seems all odd to me as we put a whole new computer in the car. Also, I will try and clear the codes and turn it on to see if it corrects the issue and also my boyfriend is going to disconnect the battery for an hour to see if it resets it.

[fdryer]

Resetting codes via battery disconnect or using a reader with a reset command has the same effect so you're resetting twice when only one reset is needed. Whether you know it or not, once ignition is turned on and/or engine started then driven, any error codes generated are detected whether just turning on ignition or starting then driving. The entire EFI system, body control module, xmission control module, abs and airbag modules all perform their own self tests every time ignition is turned on. Electronics in vehicles are testing themselves at all times and never stops until ignition is turned off. Once error codes are found and displayed on readers, the errors are real and usually won't go away no matter how many times battery is disconnected. Electronics doesn't need power removed for an hour to reset error codes. No more than 30 seconds is needed if an error or two are false or if repairs are made to correct an error code or several codes.

[Cmarie3387]

Okay so understanding what you said and seeing the codes I posted what can be the issue?

[fdryer]

Google each code to have a general idea as there are many. My initial guess is one or two may be false. With many posts in this thread, it's difficult to follow along as changes occurred, especially after replacing the ecm. Whether error codes are new or specific to this ecm cannot be determined yet. If error codes are the same from the original ecm and new codes are added, complicates diagnosing.

You're not alone with presumptions of simply replacing the engine computer and hoping to solve every problem - the plug n' play syndrome with car electronics. There's a fine line between diagnosing a genuine ecm fault with the majority of issues usually related to wiring, sensors, incorrect shot gunning, guessing, etc.

[Cmarie3387]

Reduced power mode indicates to the throttle body did some research and has to do with the pedal on the throttle body...my boyfriend will look at it tomorrow bc it’s snowing here today! All the codes were not cleared and will clear them tomorrow and start the car

[02 LW300]

There is a throttle relearn that needs to be done per the fsm after an ecm replacement.
I would start there.

[Cmarie3387]

Andy thanks so much for this info it’s still snowing here so probably won’t be able to do this throttle body relearn until tomorrow when it stops. Now, with the last picture it seems a little confusing to me and my boyfriend I did however search for a throttle body relearn procedure online for GM cars and this is what came up.
Is this correct below?
The first one is different from the second one


Start the engine and let it idle in park for 3 minutes. During that period the idle may be higher idle than normal.
2) After 3 minutes, turn the engine off and leave it off for 60- seconds.
3) Start the engine again and let it idle in park for 3 minutes one more time. During these run periods you may see a check engine light. Scan for codes and if you get throttle body related codes, clear them.
4) If the idle speed is still off, drive the vehicle at speeds above 44-mph and operate several acceleration and deceleration cycles. Then repeat step #3 one last time.



And this is the other relearn procedure

ECU Accelerator Pedal Reset Procedure
Note Timing is critical for this to work!
1. Turn the ignition switch to on. Dash gauges lit. Don t start the engine!
2. Wait 3 seconds.
3. Fully depress and release the accelerator pedal 5 times within 5 second.
4. Wait 7 to 10 seconds.
5. Fully depress the accelerator pedal for approximately 10 seconds. At this point the check engine light starts blinking quickly indicating Diagnostic Test Mode II (Self-diagnostic results) has started.
6. Release accelerator pedal and wait 5 to 10 seconds.
7. Fully depress the accelerator pedal for 10 seconds. At this point the check engine light should change to blinking slowly indicating “Erasing ECU Memory”.
8. Release the accelerator pedal and turn the ignition switch to off.
9. Restart the engine. The check engine light should be out.
Note: If the check engine light doesn't blink as described in steps 5 & 7, then the ECU isn't reset.
* If above didn't work, disconnect the battery negative and pump the brake to discharge the ECU capacitors. This method is almost foolproof as long as all ECU control parameters are within their normal ranges.
Resetting The Throttle Body Calibration (this step is conditional)
A Rough Idle or a SES can sometimes be caused by a change in the throttle body position sensor calibration. To correct any accidental changes in throttle body calibration, use these procedures to recalibrate.
Note: These procedures are a little tricky to do. You must get the timing just right Use a stop watch to help the precision of your timing.
Accelerator Pedal Release Position Learning Procedure.
Make sure that the accelerator pedal is fully released. Turn ignition switch “ON” and wait at least 2 seconds. Turn ignition switch “OFF” wait at least 10 seconds. Turn ignition switch “ON” and wait at least 2 seconds. Turn ignition switch “OFF” wait at least 10 seconds.
Throttle Valve Closed Position Learning.
1. Make sure that accelerator pedal is fully released:
2. Turn ignition switch is “ON”.
3. Turn ignition switch is “OFF’ wait at least 10 seconds.
Make sure that the throttle valve moves during above 10 seconds by confirming the operating sound.
Idle Air Volume Learning (Throttle Position Learning)
It's best to time with a watch/clock.
1. Perform “Accelerator Pedal Released Position Learning”.
2. Perform “Throttle Valve Closed Position Learning”.
3. Start engine and warm it up to normal operating temperature.
4. Turn ignition switch “OFF” and wait at least 10 seconds.
5. Conform that accelerator pedal is fully released, turn ignition switch “ON” and wait 3 seconds.
6. Repeat the following (steps 7a, 7b) procedures quickly five times within 5 seconds.
7a. Fully depress the accelerator pedal (HARD)
7b. Fully release the accelerator pedal.
8. Wait 7 seconds, fully depress the accelerator pedal and keep it for approx. 20 seconds until the Check Engine Light (CEL) stops blinking and turned ON. .
9. Fully release the accelerator pedal within 3 seconds after the CEL is ON.
10. Start engine and let it idle.
11. Wait 20 seconds.
12. Rev up the engine two or three times and make sure the idle speed and ignition timing are within the speciations.



Which one should I do and is more accurate?

[02 LW300]

What I posted is what I would do not the other ones you found. Our cars are different from most other GM cars. The only other GM car that uses your particular v6 is a Cadillac Catera. I took this information out of the factory service manual for your exact 2002 car. I hope this helps