legacycentral bbs

Okay, so ya know when you push the CC button, it makes a clicky sound in the glovebox area?....

Well, this morning, on my way to school, I heard that clicky sound, and I did not have the CC on. It has been happening randomly all day, and when it happens, there is a VERY slight shift in the transmission. Like when you hit coast going downhill, pretty much, only enough to notice if you're paying attention, on a very level road, going at a constant rate of speed. Any clues?

I'm not sure I understand quite what you mean about the slight shift in the transmission. Does this phenomenon happen if you just turn on cruise control (but don't set it) while driving?

I do know that the cruise control computer does inform the TCU when cruise control is engaged, but I don't know what the TCU does with that information.

But in any case, that clicking sound is the cruise control relay. It's mounted near the cruise control computer behind and to the right of the glove box. It's supposed to be activated by the cruise control computer when you press the cruise control switch.

If I'm interpreting the wiring diagrams right, the little orange light in the cruise control switch is supposed to be controlled by the relay... When that clicking happens, does that orange light come on?

Also, what happens if you turn cruise control on? Does the relay still keep randomly clicking?

Without knowing anything more, I'd have to guess that either the cruise control switch or (more likely) the computer itself has gone bad and that cruise control is being turned on when you didn't turn it on.

If it's a loose connection or intermittent short inside the control unit or something, then jiggling it should make the clicking happen. You could try seeing if that's the case.

If you don't really care for cruise control you could just unplug the three harness connectors on the control unit. If you need another control unit, I believe I might have one from a 1990 Legacy AT somewhere; let me know if you'd like me to look for it. I've got an extra switch too.

THe light does not come on, nor can I get CC to engage when it's not on. It's nothing that I'm particularly worried about, just curious. I dont run cruise control very often anymore, so I dont know if it does it when CC's on.

Ah...

I'd bet good money that your cruise control computer's the culprit. You may want to yank its harness connectors just to make sure it doesn't start doing weird things with your throttle when you don't want it to... Or at least pull and plug the vacuum line to the actuator underhood.

(by the way: "good money" means legal tender, not necessarily a lot of it... )

My guess would be the switch itself. In one of my legacy I have to press the switch a few times to get it to engauge properly. During that time the relay in the dash clicks on and off a few times.

I have that problem occasionally(read:very rarely) too...

I think the best plan of action is none, at least for now. If it gets worse, then I'll see about unplugging the CC comp.

Thanks.

Take the switch out of the dash and take it apart. Once you unclip it slide the button out and you will see the part that moves. Clean the contacts and remove and hardened grease. It may fix it.

AHA! Did that with my crx sunroof switch about 2 years back. I dont care that much.

So why did you post anything in the first place?

my problem has nothing to do with the switch. The switch does not move when it makes the clicking sound.

You know that for sure? If the button is loose from the portion that makes contact it can move back and forth with the motion of the vehicle.

yeah, i've messed with the button, trying to figure out what the hell was wrong. Now that my dash is torn apart, I may as well take it apart and clean it, but it shouldnt change anything.

I was wondering, what role does that relay play anyways? Usually you have a high draw device connected to the other side but I cant think of anything in the cruise system that would need it. Anyone know?

LaureltheQueen: You know, I think the relay for the AC is also in that area. What if its not the CC after all?

vacuum pump for the CC is a high draw device.

Yes, the pump is what draws most of the current, but ciper's still right... it's a weird setup.

The reason it's weird is that the pump is powered directly from the cruise control computer. The cruise control relay provides current to the computer which sends it on to the pump. And the relay is not switched on by the switch; the switch signal goes straight to the computer, and the computer switches the relay on and off.

So... there doesn't seem to be a good explanation for why the relay has to exist, since it's controlled by the computer anyway. The computer could just as easily always be supplied with a high current power supply, since it controls whether or not it's supplied to the pump motor anyway.

My AC hasnt worked for the better part of a decade.

yeah....that is weird......like you said.....I would probably venture the computer is fed with high current power.....but that still is weird....because you don't really want to be feeding lots of juice into electronics......unless the computer has a "built-in" type relay.

Well, the computer has to control the current anyway. I'd venture that it does it using solid-state transistors (like how the ECU controls the injectors and other solenoids)...

The relay does supply the computer with high current power, and the computer relays (sorry, I couldn't come up with a better word) the power on to the motor.

vrg3,

you've got a PM!