89 honda prelude cruise control

Tell us a little more about the problem. Does the main switch light come on? Can the control be set? Does the dash indicator light come on? Is it just that you're not seeing the dash light and it actually will control the speed?

The main switch light does come on but it won't set. I hit the set switch but it won't set.

Verify that it's not just the indicator lamp. Does the car hold speed if you set the cruise control even with the dash light is not illuminated?

If it's really not setting, there is another fuse under the dash to check. (I'm referring to my copy of the 1988 service manual so your vehicle may be different.) The 7.5 ampere fuse number 10 protects the main switch but that's okay if the main switch light is on. The 10 ampere fuse number 13 feeds the dash setting indicator. Check that one.

Verify that the brake lights are working.

Verify that the horns work. (I'm not kidding. They're in the circuit too.)

There are two sets of contacts on the brake light switch. The normally closed set sends voltage to the cruise control unit when the brake pedal is not depressed. With the cruise control main switch (and ignition) on, verify that you have 12 volts DC on both sides of that switch when the pedal is at rest. The wires are probably light green coming from the main switch and grey going to the cruise control unit. (The other pair controlling the brake lights are white/green and green/white.)

If the brake switch and the other items listed above are working it could be a bad ground, the slip ring behind the steering wheel, the shift position switch (or clutch switch) or the cruise control unit.

Also make sure that you listen to Car Talk every week on National Public Radio.