I OWN A 2012 xB 2.4 AND I RECENTLY REPLACED MY ALTERNATOR,CLEANED THE THROTTLE BODY,CHANGED THE OIL AND CLEANED THE MAF SENSOR.AFTER I WAS DONE WITH THAT STUFF I TOOK HER OUT FOR A TEST RUN AND SHE RAN REALLY GOOD.WHEN I GOT BACK TO THE HOUSE I HOPPED OUT AND LET HER SIT THERE AND IDLE WHILE I LOOKED EVERYTHING OVER. EVERYTHING WAS FINE EXCEPT WHEN THE COOLING FANS CAME ON SHE TRIED TO STALL.THAT WAS WHEN I NOTICED THE THE CAR WAS NOT IDILING RIGHT. IT WAS IDILING AT ABOUT 600 R.P.M. AND SHOULD BE AROUND 750 R.PM. THAT IS WHEN I SHUT IT OFF AND I REMOVED THE BATTERY CABLES AND CLEANED THE CORROSION OFF THEM(THE CORROSION WAS'NT TOO BAD) AND I REMOVED THE NEGATIVE BATTERY CABLE COMPLETELY AND CLEANED IT WHERE IT CONNECTS TO GROUND NEAR THE FUSE BLOCK AND THE E.C.U. IN THE ENGINE COMPARTMENT.I PUT EVERYTHING BACK TOGETHER AND WHEN I TRIED TO START IT IT WOULD TURN OVER BUT IT WOULD'NT RUN . THERE WAS NO POWER TO RADIO,OUTSIDE REARVIEW MIRRORS AND THE ONLY LIGHT THAT WORKED ON THE INSTRUMENT PANEL WAS THE OPEN DOOR LIGHT.I THEN I HOOKED UP MY O.B.D 2 TO SEE IF I COULD GET A CODE BUT IT HAD A LINK ERROR SO I STARTED CHECKING FUSES.NO FUSES WERE BLOWN UNDER THE DASH OR IN THE ENGINE COMPARTMENT.I THEN SHOT A TINY AMOUNT OF ETHER IN THE THROTTLE BODY WHILE MY BROTHER TURNED IT OVER AND THE ENGINE TRIED TO RUN.THEN I CHECKED FOR POWER AT THE FUEL PUMP CONNECTOR UNDER THE BACK SEAT AND THERE WAS NO POWER TO FUEL PUMP. I DON'T KNOW WHAT THE HECK TO DO NOW!PLEEEEEEEEEEZ SOMEONE HELP ME OUT WITH THIS I'M GOING CRAZY TRYING TO FIGURE OUT WHAT IS WRONG!!! MY CAR WAS RUNNING GREAT EXCEPT FOR THE LOW IDLE AND ALL I DID WAS CLEAN THE BATTERY CABLES AFTER I NOTICED THE LOW IDLE.


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Typing in all caps makes your post a little difficult to read.

 

I just got back from Wal Mart. I bought a new keyboard.It's hard not to type in all caps when the CAPS LOCK button is stuck.

 

@nugg, Hi, did you check the injectors, spark-plugs, and the catalytic converter? Those are responsible for low idle engine in parking mode. (also check if in the tank you have Gas).

 

There was nothing wrong with the car initially. If you disconnected the MAF to clean it and at any point turned the key on the ECU has to re-learn how the car runs, or if you disconnected the battery at all. That is why it was running poorly at idle. It takes about 15-30 minutes of driving to complete the re-learn.

When you disconnected the battery terminals you may grounded out the positive and blown one of the fusible links. They are in the engine compartment fuse box under the white cover on the right side when looking at it from the front of the car. Test them with a mulitmeter to see if one is blown. If it is you have to replace the whole block together, they are not individually replaceable. Even replacing the block is a pain but can be done. Service manual says to replace the whole fuse block, but that is costly. Here's a pic of the fuse block, the white portion is the fusible links.

 

Sounds to me something went wrong when the battery was re-connected. Once I connected a Honda battery backwards and it blew a main power fuse and nothing could get power anymore just like your situation no radio, fuel, etc. Maybe something shorted when working with the cables. Check "EFI MAIN" on engine fuse box I think 30amp fuse.

 

 

Well I have spark but no power to fuel pump. It ran for a second when I shot a little ether in throttle body. My obd code reader has a link error that never happened before so I am trying to see if I some how have tripped antitheft or something like that.
As far as fuses I have no blown fuses in the engine compartment or in the cab. Fusible links OK. I'm going to go back and check everything I did after I got back from driving it when I replaced alternator. I appreciate the input from everyone.

 

@nugg, I ask my mechanic about your car problem. He say when you start this car with the key, one must press the gas pedal. If it start only with the gas pedal then the fault may be the Idle air control valve.
There must be something not clean inside (to remove that part need to remove two bolts and one nut I think?) Also to check the PCV valve if is clean.

I do not know if is possible to up-grade Scion xB first generation car computer? Can some one erase and then reinstall the car computer program? Or this will be done only in the next cars future generation?

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I disagree...like others have said the initial problem with the low idle likely happened after the MAF was cleaned originally. For the OP, what did you use to clean the MAF?

The subsequent issue with no power to the fuel pump and other circuits...are you absolutely you don't have any blown fuses? You also said you removed the negative battery cable completely to clean it...are you sure you put it back in the original place as it could be a grounding issue also from the sounds of it. Might want to look at that negative cable as with the age of it and removing it and putting it back in it could have been damaged.

 

Nugg, do you want the wiring diagram for the engine control system? If so message me, I've got it in PDF. Then you can see what isn't working and try to trace down the common point they all go through. It'll either be a fuse, plug or ground point.

 

I used MAF sensor cleaner for the MAF and I have checked all fuses in engine bay and in the cab 3 times with my multimeter and they are all good. I just replaced all the fuses with brand new ones to eliminate the fuses as the problem. I am moving to wiring diagrams in repair manual to find a circuit that has radio,fuel pump and outside rearview mirrors in it and see if there is a relay controlling them.

 

I have a repair manual with wiring diagrams but I would like to look at what you have to compare the two.

 

Here you go. Probably the same as you have though.

 

@nugg, I am sorry that you have a car problem. I know that usually it is a free diagnostic at the Garage. It is possible if you go to Toyota dealer (face-to-face) and tell your story, someone can come up with a solution? Maybe because is modern car needs a modern solution?
In New Jersey are nomad car mechanics. They can come to your place diagnose a problem, and fix your car at your home. My neighbors are Uber/delivery drivers and are used to call them like every 3-4 Months.

 

I want to apologize for taking forever to get back to you guys. I have been pretty sick but I'm a lot better now. I also would like to say THANK YOU to everyone that has tried to help me out with car. I did have a lot of time to study all of the schematics of the components that I lost power to the radio,outside rearview mirrors & fuel pump. I also couldn't communicate with the ECM with my Diagnostic scanner. I am concentrating on the electrical circuits that handle the components lost power and also the DLC 3 to ECM circuit. Also the ACC circuits. I believe now that I will find an issue with a relay in one of these circuits or possibly the ECM. I will post whatever I find out that's caused this issue.