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Discussion Starter · #1 ·
This car is driving us insane and with he current car market, we can not find another vehicle
My brother had the car. Went into power reduction mode . Had the throttle body and senor replaced.
I got the car from him and had the same issue. We have now had the accelerator pedal replaced 2x in 2 years as well as the throttle body sensor. We have wen through all the wiring and checked for wear around the engine - even adding flex tubing on wires near anywhere that could rub. It is fine on long runs. When you hit city traffic and heat builds up a little, that's when it falters.
We have had it to two dealers and got no where but a smaller checking account.
Any ideas? Wheel bearing sensor? Trans temp sensor?
 

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Discussion Starter · #3 ·
I do not recall the code, but the mechanic said it referenced the 5 volt for the throttle body, the pedal position sensor, the signals for the wheel bearing, transmission sensor as well I believe
 

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2009 Impala SS
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You need to get a look at the sensor data when the problem is occurring.
Logging the TPS, ABS wheel sensor, PPS, VSS, ... on a graph on your diag tool may point you in the direction of the problem.
If you don't have the diag tools you need to buy them and learn to use them or find a real mechanic that's not a parts changer to dig into it. Dealerships are generally worthless for this kind of work. Some aren't but they tend to be the most expensive and the least effective on this kind of repair.

It could be a lot of things. I've seen PCM/ECM/TCM flaking out from thermal problems but don't just load the canon and blast a replacement ECM at it. It could be Bad sensors, Shorts in the wiring, ... Get a look at the data and let it lead you to the problem if at all possible.

Was the cop wiring unceremoniously cut off and jammed under the RH carpet or along the transmission/exhaust tunnel like most used cop cars? If it was, lord knows what's shorting out against the floorboards under the carpet.
In my former life I was a field systems integration engineer for AVL & passenger Data acquisition on public transit vehicles along with data acquisition on DOT trucks, and police/emergency vehicles so I have some experience with this stuff.
Cop AVL & ITS equipment of that vintage can utilize the VSS, TPS, and other driveline sensors and the equipment installers are just as bad as car stereo installers even with supervision. I'd darn sure look at the cop wiring left in the car.
 

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Did you check the wiring under plastic panel on the header panel... The one with the two push pins by the hood latch... Those wires underneath they chop into for lights and your wheel bearing twisted wire is in that harness also it runs along in front of condenser bottom......alto air compressor ambient and crash sensor
Was the code P02138
If it was unplug each item one at a time on that 5.volt circuit till you find that the complete 5 volts is back at APP ...whatever unplugged be it a coolant fan or wheel sensor.will be the cause of your problem
Get a wiring diagram and follow that 5 volt circuit
 

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These guys are correct. Most techs I know at dealerships cannot diagnose their way out of a wet paper bag.
Make the investment in a decent diagnostic tester - not a "code checker". Bosch makes a decent tool for diy use that will help you find the problem after you do some basic work to ensure electrical connections are

1 - clean - no oils or dirt - clean it all!
2- check ALL grounds are connected securely to a clean surface
3 - no wires twisted together hiding under electrical tape - definite cause of electrical signal loss and leaky voltage which is the main reason connectors are soldered to wires or crimped and properly insulated
4 - since it was a cop car in its previous life, you must check all the wiring inside the car, under the seats, under the dash, in the trunk - each connection communicates with the various components of the entire "computer" system and most of the guys that remove data equipment are hacks, car is headed to auto auction and they could care less if it has problems they may have caused as long as it leaves their work bay on its own
5 - make sure your battery cable ends and battery are cleaned and tight to make good connection - if corroded badly at cable ends, likely the sulfur outgassing has corroded into the cable and it will need replacing, including those smaller wires that are connected to the battery.
6 - Check voltage with a digital multimeter - most cars require at least 12.7 - 14.2 to start. Losing voltage after initial starting of engine will give you nightmares and a myriad of fault codes that may not actually be faulty sensors but a sequential response to bad wiring.
7 - Buy a GM service manual exactly for your year and model (ebay) or at least a Chilton's manual and READ IT. Knowledge is $$$. The more you can make yourself aware of how something works, the less likely you will get ripped off on repairs.

Electrical issues are not money makers - most techs will not invest in the diagnostic tools to locate and resolve these issues. They make more money replacing parts you may not need. A good tech will give you a print out of all the diagnostics on your vehicle and will stand behind the repairs and explain why it needed replacement and show you the bad part. Ask people at parts store about reliable shops - they know who is good and who is a parts replacer.
Good luck.
Me? 35+ years as mechanic - from restoring old cars, building mud trucks and dirt/asphalt stock cars, working in a junkyard (best job ever), repairing industrial equipment, CNC work and turning wrenches on big diesel bohemoths - never be fooled about a woman's looks vs her intelligence, I can disable your truck in a few minutes with simple tools and a rocket scientist will not be able to make it run again!
 

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Interesting you were talking about scanners... There is one out there made by Vident with lLink 400 software for GM's Chevy... 200 bones us on Eboy
I have been testing a friend brought over to me
Cheap connector but has quite alot of bidirectional functions
Seems to be a tech 2 clone
Not a snap on for sure missing lots but great for a diy ...quite impressive for the cost l must say.
 
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