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Discussion Starter · #1 ·
I could post a thread asking for wild random theories, but instead I'll fire up VIDA in the morning, clear codes, drive around the block, and see what comes back, before resorting to random speculation.

Stay tuned, folks!
 

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Discussion Starter · #2 ·
ECM-9520, Accelerator Pedal position sensor analog signal - Faulty signal. Code did NOT recur once cleared and taken for a test drive, so I shall assume a connector was jostled during that really alarming jolt. All is well for now, nothing to see here...
 

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Even if the code went away and it was the result of the bump, you might want to rest the connector to the pedal sensor, not exactly something you want to have a bad connection to.
 

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Could be anything from connectors to a cooked module of sorts
 

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Discussion Starter · #5 ·
^ I'll go digging around in the footwell and reseat everything soon.
 

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Discussion Starter · #6 ·
It's baaaaack.

Happened once or twice more, so I swapped in a used pedal assembly, and everything was peachy for awhile...until this afternoon, when I went over another bump (a fairly minor one this time) and immediately got "reduced engine performance": no boost, very slow revving, and most interestingly of all, no revs at all if the brake pedal is depressed at the same time as the gas pedal. Turning the car off and on again doesn't get rid of the CEL, but does clear the limp mode.
 

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Discussion Starter · #7 ·
This looks promising. From a thread on matthewsvolvosite:

The ECM-9520 (brake pedal position sensor) prevents throttle input while the brake is pressed. This can be annoying for people who like to use two feet on the pedals sjuch as during parking maneuvers. Also the ETS light will come on (on pre 2001 cars)

Proof of this is if you disconnect the 2 pin connector on the brake booster the ETS will light and accelerator will be dead while brake is on.

The only way to rid yourself of ECM-9520 permanently is to replace the pedal sensor or open it up and resolder the connector area to the logic board inside the cylinder cssing.
Anyone else experience something like this? I know early P2s had some goofy throttle-by-wire issues with their Magnetti Marelli throttle assemblies, but was under the impression later models (including Rs) were generally pretty solid there.
 

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Discussion Starter · #8 ·
Went down to the local pick 'n pull and fished one of these out of a very smashed S60:



No codes so far, but I'll give it a few more days of driving to make sure.
 

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Discussion Starter · #9 ·
It's baaaack.

Generic OBD code P2126, "Throttle/Pedal Position Sensor/Switch E Circuit Range/Performance". Replaced with a fresh accelerator pedal, no effect.

Symptoms:
-Limp mode
-No throttle response at all if brake is pressed at the same time as the gas pedal

Wondering if my brake pedal position sensor is on the fritz again, or if it's some other exciting thing like the throttle body or something completely unrelated.

Anyone else have any input on this one?
 

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weird that it took this long to come back...


Sent from my iPhone using Tapatalk
 

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Discussion Starter · #11 ·
weird that it took this long to come back...


Sent from my iPhone using Tapatalk
No kidding. Since it was gone for another 9 months, I'm inclined to think something failed/broke. As I'm getting the same code and behavior as before, my first guess is it's that brake booster sensor again...but again? Are failures there really that common?
 

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It's baaaack.

Generic OBD code P2126, "Throttle/Pedal Position Sensor/Switch E Circuit Range/Performance". Replaced with a fresh accelerator pedal, no effect.

Symptoms:
-Limp mode
-No throttle response at all if brake is pressed at the same time as the gas pedal

Wondering if my brake pedal position sensor is on the fritz again, or if it's some other exciting thing like the throttle body or something completely unrelated.
Anyone else have any input on this one?

I was wondering why you had it up on blocks yesterday. Anyway, are you sure that something else hasn't gotten lose / are you sure that all of your connectors are tight? Also, are the connectors clean?
 

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If you are still getting this despite being on the second replacement throttle, its time to check the connectors and wiring. Try to trace the pedal wiring around the footwell, it could be rubbing on something down there and only shorting when you hit a bump the right way.
 

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Discussion Starter · #14 ·
I was wondering why you had it up on blocks yesterday. Anyway, are you sure that something else hasn't gotten lose / are you sure that all of your connectors are tight? Also, are the connectors clean?
Had it up on blocks yesterday because I was replacing an axle, haha. This code and limp mode started appearing early last week, even before I ripped everything apart to replace my clutch (again) and fix my busted 1st/2nd gear.
 

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Discussion Starter · #15 ·
If you are still getting this despite being on the second replacement throttle, its time to check the connectors and wiring. Try to trace the pedal wiring around the footwell, it could be rubbing on something down there and only shorting when you hit a bump the right way.
I'll reseat the connector, make sure everything's tight down there. As I'm not getting any revs at all when the brake is pressed at the same time as the throttle, though, I'm inclined to think this one's trouble with the brake position sensor again.
 
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