Technical Code P1220-62 diagnose help and fix

[Dsdsdk]

Hi my fellow Tonys

Fiat 500C 1.2 2010.

I'm getting Check Engine, ABS ECS Hillhold error in dashboard. I've cleared DTC with MES, but error returns seemingly random, either at startup or while driving.
MES shows P1220-62 Intermittent issue with signal compare Track 2 of accelerator pedal potentiometer.

Caught it once on Livedata and Track 1 showed 0,75v and Track 2 showed 0,35v (key only turned to ACC). I turned car off/on (ACC). Track 1 and 2 now showed 0,75v!

Pedal has been replaced but issue persists. I've jiggled all cables at pedal and ecu. Sprayed pedal plug.

I'm thinking the ECU is at fault and only giving ~half voltage. Restarting it seems to solve it (but limp mode persists until I clear DTC).

Other than changing ECU, how could I fix this? Would it be possible to cut wires at pedal plug and loop Track1 5v to Track2 5v?

Does anyone have diagrams/ressources on accelerator pedal/throttle system or knowledge about the pinout?

 

[ZaphodB]

Other than changing ECU, how could I fix this? Would it be possible to cut wires at pedal plug and loop Track1 5v to Track2 5v?

There are two resistance tracks on every pedal on purpose to ensure if one fails (with an inplausible value etc) there is a backup to confirm position.
So do not mess with the pedal wiring or try and bridge them.

Besides if you've changed the pedal why carry on looking in that area

I'd check condition of main engine earth cable and its connections are good. (remake if necessary to be double sure if they look crusty)
(or use a temporary jump lead gauged cable from battery -ve to engine metalwork.)

Also worth looking at your brake pedal switch and it's position/adjustment.

 

[Dsdsdk]

Thanks.

Brake pedal MES livedata is solid.
I've checked cable between battery and gearbox and frame. All good.

 

[ZaphodB]

Thanks.

Brake pedal MES livedata is solid.
I've checked cable between battery and gearbox and frame. All good.

I'd be looking for possible corrosion on 'external' connectors now to and from ECU , a close examination of both male and female pins and sockets

 

[Dsdsdk]

Good idea. I'll give them a look.
Is it likely this could cut voltage in half?

 

[ZaphodB]

Good idea. I'll give them a look.
Is it likely this could cut voltage in half?

Poor connections and/or earths can cause all sorts of weirdness