ecu removal

[alan forbes]

does anyone know if there is a correct/ incorrect way to remove & refit an ecu, eg do you have to disconect the battery first ?

[mjb]

No, just unplug it...

[muffindell]

Does that mean that the ecu is only active with ignition on?

[steve_earwig]

Doesn't that depend on which ecu it is? Haynes would say diconnect the battery, you can't go far wrong with that. I'd guess it'd be an idea to leave it a while too so any stored charge gets a chance to dissipate.

[teamster1975]

I agree Steve. I wouldn't fancy the chance of a connector arcing as it's unplugged

[mjb]

I agree Steve. I wouldn't fancy the chance of a connector arcing as it's unplugged

If memory serves, it takes a potential difference of around 3000V to arc just 1mm through air. Given we're talking about connectors which normally live together I can't see there being any problem with removal. You COULD cause a static discharge of such voltage on insertion though if you manage to avoid touching the bodywork with the ECU in your hands, but the chances of that are realistically pretty slim.

If you're really worried, disconnecting the battery for half hour will help, but you'd still need to take the precaution of touching the bodywork (and ECU case at the same time) before connecting the new ECU as a car sitting on rubber wheels is still effectively a large capacitor

[teamster1975]

If you're really worried, disconnecting the battery for half hour will help, but you'd still need to take the precaution of touching the bodywork (and ECU case at the same time) before connecting the new ECU as a car sitting on rubber wheels is still effectively a large capacitor

Oh the memories of college and blowing up capacitors!

[steve_earwig]

If memory serves, it takes a potential difference of around 3000V to arc just 1mm through air. Given we're talking about connectors which normally live together I can't see there being any problem with removal. You COULD cause a static discharge of such voltage on insertion though if you manage to avoid touching the bodywork with the ECU in your hands, but the chances of that are realistically pretty slim.

Zap! Depends on all sorts of things, moisture, humidity, corrosion etc. etc. etc. I know the big capacitors we used to leave on the end of phone lines for testing could give you one hell of a shock and that's only 50 volts, I was just playing it safe. Besides, it wasn't specified what ecu, how about the airbag?

How about using an earth strap? They used to bang on all the time at work about "soft zapping", i.e. giving something a severe jolt of static that didn't kill it straight off but seriously reduced its lifespan, taking into account the amount of ecus on these cars that display a marked propensity to go pop all the time do we really want to give them more excuses? *dons tin foil hat*