Wires crossed... Cruise not right

[Pix]

The other morning driving to work I noticed my cruise control wasn't working, slightly annoyed I left it until the afternoon to check it. On the way home the cruise worked perfectly. The next morning I tried to use it again with no success I then went through the "what's different" checklist in my head. Turns out its my headlights. If they're on my cruise won't work, even if I've already got cruise set and using it then flick the lights on it switched the cruise off. Slightly baffled I had to wait until today to have a peep. When I pulled up at home to inspect the cruise I turned the car off and notice my headlights still but no buzzer going off, great problem number two!
I then pulled the dash and started to inspect the rats nest that has befallen my under dash area. I managed to locate what I hope is the problem, but don't want to have to fit anything else under the dash. With cruise control, UHF, mongoose alarm/turbo timer, new speakers, head unit, mobile phone speaker and whatever else is wired under there, is there anyway I could clear it out or relocate anything to make it neater? Has anyone go anything like this lurking in their Nav?

 

[Pix]

So my hopeful guess was wrong and cruise control isn't fixed, still switches off off when my light get turned on... Not happy.

 

[Old.Tony]

The cruise control might be earthed on a point where the headlights are taking that earth away? Here's something to try (and at least you don't have to be cruising at 80km/h to test this).

Grab a multimeter and start your engine with the cruise control unit accessible. Check that the power to the unit is good by measuring across the unit itself (should - as is typical for 12V installations - be a black wire for negative, and a red for positive). You should get a very similar voltage to what is across your battery.

Now turn on the headlights and test again. If the power is gone, we need to do two further tests. If it's still there, it must be related to the speed sensor or something, not sure as I don't have the wiring diagram for your unit handy.

If there's now no power, you have to work out which one has lost power. First (and easiest), leave the multimeter connected to the red lead on the cruise control and touch the other lead of the multimeter to a shiny bolt somewhere under the dash. If there's power, then the earth is compromised. If there's no power, then it's possible that the headlight relay is turning off the juice.

Start with those tests and we'll see how we go. More info would be handy!

 

[04SilverSTR]

Yeah im with old tony on this, maybe run a direct 12v feed to the cruise and see if this fixes it.

Bryan

 

[Pix]

Cheers Tony, I'll be doing this test today

 

[Kung-Foo-Kamel]

You may have picked up your earth point for the cruise control module from the park light 12v feed

when the lights are off the the 12v feed goes to negative ground (low), when you activate the park light circuit the feed goes to 12v positive (high) this is more than likely why your cruise control cuts out when you turn your lights on

Always earth all after market accessories to the body of the vehicle, this will eliminate this issue, I have seen novices do this many times usually during a stereo install

Also easy way to eliminate that rats nest of wires is fit one thing at a time, loom everything up nice and neat like the factory wiring, use strategically placed cable ties and run wires and modules as high as posible, also avoid moving parts like pedals and steering knuckles

Hopefully this info helps you (and anyone else reading this)

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