Out of ideas, can't fix ETC Failsafe.. Please help.

Here’s the voltage

FCA09339-EC26-430D-AA69-D1403CEA4F1D.jpeg
 
Will you also check and see if yours will start and run with the maf unplugged. Mine may start, but dies right after.
 
Here’s what’s happening to my throttle control when it starts running bad. From top to bottom
ETC [TAC_PCT]
ETC_ACT
ETC_DSD
TP.OBDII
TP1

5B6DF42C-CDF4-47A2-95DD-308136AB9CA0.jpeg
 
If it’s in fact the pcm AGAIN, what should I be looking at as far as the pcm taking another dump? Wiring, grounds? Etc.
 
Dan Swenson said:
If it’s in fact the pcm AGAIN, what should I be looking at as far as the pcm taking another dump? Wiring, grounds? Etc.
Click to expand...
How do you know you have a faulty PCM? Is water getting into the car somewhere? Is there evidence that the PCM is damaged?

"The onboard computer is the brains of the engine control system, so when the brain isn't functioning correctly neither is the engine or anything else that the microprocessor controls - which may include the charging system, transmission, various emission controls and communications with other onboard control modules. Once a diagnosis has been made (and I emphasize the word diagnosis), then and only then should the PCM be replaced.

PCMs typically fail for one of two reasons: voltage overloads (often due to a short in a solenoid or actuator circuit) or environmental factors (corrosion, thermal stress or vibration). If the shorted solenoid or actuator isn’t found and repaired, the voltage overload it creates may damage the replacement PCM, too."
Dan Swenson said:
If it’s in fact the pcm AGAIN
Click to expand...
So correct me if I'm wrong...but you're on your second PCM in your LS?

"Regardless of the PCM’s location, though, one thing every installer should do (but many don’t) prior to removing the old PCM and installing the replacement PCM is disconnect the battery.

Once the PCM has been installed and reconnected, the battery can be reconnected, too. But the job isn’t done yet. Many PCMs have to undergo a "relearning" procedure after they’ve been installed or if they’ve been disconnected from the battery.

On some applications, there may be a specific procedure for establishing the base idle speed. On others, it may be necessary to take the vehicle for a short test drive so the computer can adjust itself. The exact requirements will be spelled out in the vehicle’s service manual, but that doesn’t mean the installer has access to a manual or will use it. So the best advice here is to test drive the vehicle after the computer has been installed. A short drive cycle that includes going over 35 mph will usually reset most computers so they run properly.

Most PCMs will also continue to learn and make small adjustments to the fuel mixture and other functions over time as the vehicle accumulates miles. If the PCM also controls the transmission, it may take awhile to relearn the driver’s habits so the transmission may not shift exactly the same as before until this occurs.

Finally, if the Malfunction Indicator or Check Engine light comes back on after the PCM has been replaced, it means there’s still a problem with the vehicle - not the PCM (assuming the code is not one for an internal PCM fault, in which case the PCM would be saying it is faulty). The presence of fault codes means something else is wrong that needs to be diagnosed and repaired. So until the real problem is found and fixed, the PCM may not function normally.
If the engine control system is not going into closed loop, chances are the coolant sensor or oxygen sensor are not working properly. If spark timing seems to be over advanced or retarded, the problem may be a faulty MAP sensor, misadjusted throttle position sensor or overly sensitive knock sensor. And if nothing seems to work right, low charging voltage due to a weak alternator or poor battery connections may be the fault.

Remember, the PCM needs all its sensor inputs, proper battery voltage, a good ground and the ability to send out control signals to function normally."

The quoted paragraphs came from © 2011 B&B Electronics
 
Last edited:
AmsterDutch said:
How do you know you have a faulty PCM? Is water getting into the car somewhere? Is there evidence that the PCM is damaged?

"The onboard computer is the brains of the engine control system, so when the brain isn't functioning correctly neither is the engine or anything else that the microprocessor controls - which may include the charging system, transmission, various emission controls and communications with other onboard control modules. Once a diagnosis has been made (and I emphasize the word diagnosis), then and only then should the PCM be replaced.

PCMs typically fail for one of two reasons: voltage overloads (often due to a short in a solenoid or actuator circuit) or environmental factors (corrosion, thermal stress or vibration). If the shorted solenoid or actuator isn’t found and repaired, the voltage overload it creates may damage the replacement PCM, too."

So correct me if I'm wrong...but you're on your second PCM in your LS?

"Regardless of the PCM’s location, though, one thing every installer should do (but many don’t) prior to removing the old PCM and installing the replacement PCM is disconnect the battery.

Once the PCM has been installed and reconnected, the battery can be reconnected, too. But the job isn’t done yet. Many PCMs have to undergo a "relearning" procedure after they’ve been installed or if they’ve been disconnected from the battery.

On some applications, there may be a specific procedure for establishing the base idle speed. On others, it may be necessary to take the vehicle for a short test drive so the computer can adjust itself. The exact requirements will be spelled out in the vehicle’s service manual, but that doesn’t mean the installer has access to a manual or will use it. So the best advice here is to test drive the vehicle after the computer has been installed. A short drive cycle that includes going over 35 mph will usually reset most computers so they run properly.

Most PCMs will also continue to learn and make small adjustments to the fuel mixture and other functions over time as the vehicle accumulates miles. If the PCM also controls the transmission, it may take awhile to relearn the driver’s habits so the transmission may not shift exactly the same as before until this occurs.

Finally, if the Malfunction Indicator or Check Engine light comes back on after the PCM has been replaced, it means there’s still a problem with the vehicle - not the PCM (assuming the code is not one for an internal PCM fault, in which case the PCM would be saying it is faulty). The presence of fault codes means something else is wrong that needs to be diagnosed and repaired. So until the real problem is found and fixed, the PCM may not function normally.
If the engine control system is not going into closed loop, chances are the coolant sensor or oxygen sensor are not working properly. If spark timing seems to be over advanced or retarded, the problem may be a faulty MAP sensor, misadjusted throttle position sensor or overly sensitive knock sensor. And if nothing seems to work right, low charging voltage due to a weak alternator or poor battery connections may be the fault.

Remember, the PCM needs all its sensor inputs, proper battery voltage, a good ground and the ability to send out control signals to function normally."

The quoted paragraphs came from © 2011 B&B Electronics
Click to expand...
Yes, this is the replacement PCM. So either the first PCM was either good and the problem was certainly something else. Or the culprit for the first failing PCM is causing this as well. OR the problem really isn’t the PCM at all still. I printed off a bunch of wiring diagrams and I plan on taking a look at the whole wiring harness the best I can.
 
But the biggest thing about it all is the fact that only once it’s warm it begins to run rough. Prior to that it’s fine. Going to focus on the wiring for the ETC first and see if maybe once the wiring is getting warm maybe there’s a wire with an issue.
 
Dan Swenson said:
Yes, this is the replacement PCM. So either the first PCM was either good and the problem was certainly something else. Or the culprit for the first failing PCM is causing this as well. OR the problem really isn’t the PCM at all still. I printed off a bunch of wiring diagrams and I plan on taking a look at the whole wiring harness the best I can.
Click to expand...
Yes ...I think you understand what the article was saying
 
Ok. It’s been on for a month or so but I’ve heard people say there is a relearn process. The TB had a tag saying something about it as well but no specific instruction. Was just curious.
 
Dan Swenson said:
But the biggest thing about it all is the fact that only once it’s warm it begins to run rough. Prior to that it’s fine.
Click to expand...
FYI ...You must ask yourself this one question before you start to tackle this problematic situation...What changes when the car gets hot or should we say after it gets hot? ....Answer : EVERYTHING
 
Literally everything changes on a engine after it heats up...
  • Your Oil Gets Thinner
  • Your hoses can become more supple
  • your contacts for all your connecters are going to change
  • The resistance in the wires are going to change
  • gaps are going to expand in the metal and in the hoses and different materials
  • You could start to get air bubbles in the fuel system
  • Bad electrical connections
  • The tolerances in the cylinders seem to get tighter
Literally everything is affected by heat in an engine ...but one of the main things that heat can affect and is really hard to troubleshoot are your injectors and sometimes the smallest thing wrong with them can cause bad things to happen to the performance of your engine
The good news is you can test your injectors to make sure there performing properly and I also can't stress enough how crucial it is to test your catalytic converters
 
AmsterDutch said:
Literally everything changes on a engine after it heats up...
  • Your Oil Gets Thinner
  • Your hoses can become more supple
  • your contacts for all your connecters are going to change
  • The resistance in the wires are going to change
  • gaps are going to expand in the metal and in the hoses and different materials
  • You could start to get air bubbles in the fuel system
  • Bad electrical connections
  • The tolerances in the cylinders seem to get tighter
Literally everything is affected by heat in an engine ...but one of the main things that heat can affect and is really hard to troubleshoot are your injectors and sometimes the smallest thing wrong with them can cause bad things to happen to the performance of your engine
The good news is you can test your injectors to make sure there performing properly and I also can't stress enough how crucial it is to test your catalytic converters
Click to expand...
Tips on testing injectors?
Can I test the catalytic converters myself?
 
Key on/Engine off, wot on accelerator. Should I hear a constant humm or buzz from the throttle body? Every once in a while the butterfly will twitch. Seems odd.
 
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