shielding for cruise control

I recently posted question reguarding my cruise control pulsating with my turn indicator. The reply I got back was that the cruise control computer is not properly shielded and a feedback was beign created by the indicator unit. I was wondering first where this unit is in a 1984 230e and second, what is suitable to shield it with? A friend says that I can use aluminium foil, but I just can't believe that it would be that easy. Is he correct? Thank you for your time.