I don't know how effective the ECCM in an AMRAAM is (and I'd be worried if I did), but one thing you can say for sure is that the power output of a 7" diameter radar set is not going to be great, so you'd stand a fair chance of wiping it out with sheer jamming power, particularly from a big aircraft with lots of jamming capability. Of course, it's not quite a simple as that since a) the missile's radar is frequency agile, so you'd have to either jam a range of frequencies or follow it's frequency shifts very quickly and b) it's likely to have a home-on-jam mode, where it just stops listening for it's own echoes and uses your jammer as a homing beacon.
The alternative is deception jamming, where you try to spoof the missile's "noise filters" into rejecting the true echoes and listening to your fake ones that give incorrect bearing/range data. How good your jammer is at doing this and how good the missile is at avoiding it are deeply black subjects and the only thing you can say for sure is that anything in the public domain will be either too non-specific to let you apply it to a particular system, or downright disinformation.
My best guess would be that a really smart jammer would use a mixture of noise and deception jamming, changing tactic second-by-second to force the missile's ECCM to try to keep up. It might not be able to completely break the missile's lock, but if it keeps breaking lock momentarily and then having to re-acquire it will "dither" to the point where it's miss-distance increases beyond it's lethal radius.