10 replies to this topic

[rabidh]

I went to leave from work today, and just as I went to pull onto the road the throttle pedal stopped working. I coasted to the side, turned the engine off and back on and all was fine (bar a MIL light), and I drove back home.

I just plugged in my OBD reader and got:

P1120 - TPS
P1220 - TPS Circuit 2
P1271 - Accelerator pedal circuits 1-2 correlation
P1275 - Accelerator pedal circuit 1 failure
P1280 - Accelerator pedal circuit 2 failure

That sounds pretty serious to me, given the TPS and accelerator pedal aren't really connected. Has anyone had something like this before? I've re-seated the TPS and accelerator pedal connectors, but could it be a connector on the ECU??

Or could this just be a glitch? I should probably start getting some RAC cover...

thanks!

edit: just checked -=here=- and the pedal/TPS aren't on the same ECU plug - so something is very messed up

Edited by rabidh, 25 June 2007 - 05:14 PM.

[luna_s]

itll be the throttle position sensor on top of the pedal, probably damp with all this rain

[rabidh]

Presumably 'Throttle Position Sensor' in the top two codes refers to the one on the TB though, whereas obv the last 3 are the pedal. The car is pretty dry inside. I have had to have the pedal assy off before when my pedal dropped off though! Is this likely to be a one-off? The car behaved faultlessly after re-seating the pedal + TB connector on the way back...

[rik]

what software do you use to read the codes?

[rabidh]

I have an ELM323 (ebay, £20 ) and I use scantool.net. To be honest its not much good, but it does read codes and show you some values from the ECU, which is good enough for everything i've needed so far. (Although freeze-frame data would have really helped me out in this case) edit: all it does is give me numbers (all the above were vaux specific, which I had to google)

Edited by rabidh, 25 June 2007 - 06:00 PM.

[rik]

here's the list of what can go wrong on n/a codes

http://www.speedster...el-Vauxhall.pdf

turbo http://www.speedster...el-Vauxhall.pdf

Your codes do match ones in there, and it tells you the "concerned terminals".. which is rather cryptic, but you can trace it back using the wiring diagrams on that site if you spend a few hours searching

[rabidh]

here's the list of what can go wrong on n/a codes

http://www.speedster...el-Vauxhall.pdf

turbo http://www.speedster...el-Vauxhall.pdf

Your codes do match ones in there, and it tells you the "concerned terminals".. which is rather cryptic, but you can trace it back using the wiring diagrams on that site if you spend a few hours searching

thanks. thats actually the list I found in the first place didn't see the concerned terminals bit though I guess it refers to the wires on the ECU plug...

[rik]

for example:

P1280 - Accelerator Pedal Position Sensor 2 Circuit

The control unit recognises the malfunction of the circuit via an internal
evaluation logic.
Concerned Terminals:
X21: 21, 31, 49, 53, 61, 64

find the device/connector called X21, and then the others are the pins on that device

so if you look at this, http://www.speedster...e...2SE - 1.pdf

you can see X21 is a connector on ecu, which goes to X3, which goes to B19 - sensor pedal position

the first few errors do point to the engine side throttle body thing, X22: 13,14,15,16, 26, 36, 43, 45, 55, 57, 63, 64

But I'm guessing that both your pedal and the throttle body aren't suddenly both broke (different end of car etc), so a problem in one of them has probably made it appear like there is a problem in the other, since they are obviously linked.

which one? who knows

[Steve Crisp]

Hi, My take on it is this. The throttle-pedal has two potentiometers on it (plus a few little resistors). The three connections from each of the potentiometers goes back to the ECU via three wires each, equals six wires. So each potentiometer is a totally seperate circuit going back to the ECU - hence circuit 1 and circuit 2. I would surmise that the ECU expects consistant readings from both circuits and if they differ, then it'll shut down the throttle circuit 'cause it thinks the pedal circuits are not agreeing and therefore faulty. I reckon you had a loose plug... Steve

[rabidh]

I reckon you had a loose plug...

Thats what i'm hoping. The plug was on solidly, but the whole unit has been off before so it wouldn't surprise me if it wasn't mating perfectly. Of course at the ECU end all the wires have been off too (where I had to remove the engine )

lets hope its a one-off

[snoopstah]

I would surmise that the ECU expects consistant readings from both circuits and if they differ, then it'll shut down the throttle circuit 'cause it thinks the pedal circuits are not agreeing and therefore faulty.

That's correct - although it'll allow for a little variation in the two readings before shutting down.

I think there are three main points of failure, the pedal assembly itself (or more specifically the potentiometers within it), the wiring between the pedal and the ECU (including the connectors at each end), and the ECU itself. Unfortunately, when mine failed it was the ECU that had gone (water ingress).