Solve a system of ODEs with a piecewise forcing function

I'm trying to solve a system of two ODEs with a piecewise forcing function. There are two cases, the first being instantaneous changes of the constant function. The second involves a linear decrease and increase. I haven't been able to make this work with the first case, and I'm hoping the solution works for the second as well. My code looks something like this:

funlev = [funlev1 0.5*funlev1 funlev1 0];
funp = mkpp([-12 0 48 72 180],funlev);
fun = ppval(funp,t);
fun2 = @(t,y) [A*fun-B*y(1);
            B*y(1)+C-D*y(2)-E*fun*y(2)];
[t1,y1] = ode45(fun2,[-12 180],y0);

I'm thinking the issue is with the piecewise function, but I'm not positive. Am I missing something? If I'm not handling the piecewise function correctly, how would I do so?