Why did submarines limit the use of active sonar and radar?

The main reason is that they give away your presence and location long before they provide information that is useful to you. For example, let us assume that the effective range of radar was no more than seven miles early in the war. That meant that the radar pulse was strong enough to travel 14 miles – to the enemy ship or plane and back. The issue was that the radar pulses sent out, that didn’t hit a target and return, were going to travel out 14 miles. That meant that the enemy could be aware of the submarine's presence when they were still 14 miles away but the crew wouldn't be aware of them until the enemy was within seven miles.