89240 cruise not working when headlights are on

[dlocke]

I just replaced a bad cruise control acutator with one at the junkyard. Good price at $24. I know it was bad because I did not get a vacuum when I tested it per the FSM. The ASCD works fine now EXCEPT when I flip on the headlights. I going along and the cruise is working fine. Then I turn on the running lights or headlights and the cruise light goes out on the instrument panel and the cruise control stops working. Turn the lights off and it starts working again when set it again. I have the FSM and I looked at the wiring diagram and cannot figure out how this could happen. I have spent hours on this. NISTECH, can you help me out please? I have seen some of you other excellent posts and wonder if you can help me? Another question I am curious about is the figure for the cruise control switch. I see ON, N and OFF is the diagram. What is the N for? I believe this is the switch to the left of the steering wheel. I thought there would only be on and off. I know there is a cancel switch below it that is separate.Thanks in advance.

P.S. I love working on my clean old 240sx

[onosqv]

have you checked to make sure all your running lamps are working correctly first? I know I get weird *** problems when some of my bulbs go out.

Turn on parking lamps - make sure all bulbs are lit. Press the brakes - make sure correct bulbs light up. When no in cruising, but w/ headlamps on - do you get lights on the climate control, instrument panel, and the dimmer switch?

Do you have an aftermarket radio - if that was installed tapping the wrong wire, it does weird things to ppl too.

Something must be shorting the cruise control somewhere.

[dlocke]

Well I just replaced all 4 burned out running lights on the side of the car and that did not help the non working cruise control. Man, the one in the left rear compartment was tough to get at. I am glad I fixed that anyway.

I am curious as to what kind of problems you had when yours were out?

Also what is a ppl?

I do have an aftermarket radio but I don't know how I could have hooked it up incorrectly.

A wierd thing is and I don't know if this is normal but when I press on the brake pedal the dash lights and brake lights come on even without the key in the ignition. All the brake and running lights work ok.

This is really irritating me but I am going to figure it out somehow.

I am going to start looking for shorts in the entire cruise control wiring system.

Now that I think about it I might know where the problem is. Previously the hatchback wing leaked water into the back compartment. The back wiper quit working so I had a look. The wires that go to the wiper amplifier were all melted together in a mess and I suppose it was due to water. I am going to take a look at all that now.

Thanks for the info.

Dal

[kouki_queen]

Gotta love the wiring in a 240! I have an 89 as well and the wiring was all messed up. Maybe you can take it to someone who deals with car wiring and they can figure out whats the problem?