A/T Neutral Switch

[barryware]

2007 yaris hatch / AT

When I bought the car (new), I immediately installed a Rostra cruise control. This is the same unit the dealer would install.

Lately, when the cruise control is engaged it will shut off as if you were to tap the brakes. More often than not, it shuts off when I hit a bump.

There is only one wire that goes through the firewall and connects to a wire harness plugged into the transmission. I believe this wire connects to the neutral switch wire.

My question: When the car is placed in neutral, does the neutral signal wire get grounded, or does it get a voltage signal?

I'm thinking that over the years / miles, the Rostra wire may have gotten some insulation rubbed off and now it is rattling around and when circumstances are right, the wire may go to ground and disengage the cruise.

I haven't really checked it out just yet because the weather has been so bad. Even in my garage, the floor is always wet, it is cold, etc.

[CTScott]

The connection to the blue wire in pin 9 of connector C27 on the park/neutral switch will measure 12 volts when the shifter is in the park or neutral position. Otherwise it measures zero volts. So, I don't think that wire is your issue, as it would have to short to a 12 volt source to make the rostra unit think you have shifted out of gear.

[barryware]

Thanks CT.. That is why I asked the question so I don't spend time chasing my tail.

I'll have to remove the CC module and check / clean all the connections and see if that makes a diff.

Something is loose / dirty.. Hitting bumps does make it drop out.

[CTScott]

Thanks CT.. That is why I asked the question so I don't spend time chasing my tail.

I'll have to remove the CC module and check / clean all the connections and see if that makes a diff.

Something is loose / dirty.. Hitting bumps does make it drop out.

That's a tricky one. The Rostra has a crazy number of connections and of course you can't just wiggle wires while parked to troubleshoot it.