New Here, Problem Though

Hey guys, will keep it short. I bought a little blue standard car for mpg and that it reminded me if the Little Blue Turd on Mighty Car Mods. Turns out this car is surprisingly fun and has a number of avid followers. I keep dropping money on it to get it mechanically sound and to bring it up to date aesthetically. Rebuilt the engine, several panels painted, new pistons,new clutch kit, new sparks plugs, new coils and wires, new cat converter, O2 sensors, and a bunch of little things the previous owner had done. After dropping over 4k on the car and 1 new CEL is on I decided to try and hit the internet to figure it out. Joined my first car forum ever (Mazda247) which is just full of info and helpful people it seems.

My problem- I'm getting CEL code P0705 accompanied with high idle and after warming up a rhythmic revving of the engine when ever the clutch is depressed or in neutral. From my hours of reading on here it seems to be my neutral safety switch or some break along the lines to it.

I want to mention this code only came on after putting it in the shop for over 2 months at which time it had the clutch kit installed. Upon receiving the car back the Cruise Control also no longer works (I know about the button on the steering wheel underneath the actual cruise control). I want to say that I read that somewhere along the lines a clutch sensor is connected to the cruise control? I can't find where I read that though. Also I do have some of the shop repair books and transmission rebuild books. Another note, the cooling fluid was getting to hot and boiling/steaming out of the fluid reservoir when sitting at idle for long periods (doesn't happen when going down the road, I've made sure my fluids are back where they need to be now), I can only guess that it is from the high idle caused, with high suspension, of a failure in the neutral safety switch electrical line.

Any ideas on where to start?

Respectfully
CBrn42

PS hope I didn't break any forum rules.

You may have a bad/broken neutral switch.
I would start by unplugging the switch and testing for continuity at the switch. It should switch on and off when it's in neutral or in gear.
Check the connector itself for a bad connection/broken wire.

Then check the wire for shorts or opens between the connector and pin number 64 of the ECU.

The car needs to know when it's in neutral to idle properly.



Make sure your fans are coming on... It shouldn't overheat while idling.

You may have a dead fan or bad circuit... Turn on your AC and both fans should come on.

There is two clutch switches.. One for the ECU and one for the cruise control. A brake switch ties into the cruise as well.

So I've been calling around trying to get a neutral safety switch and AutoZone only comes back with a knock sensor and my local Mazda dealership only comes back with a "pulsation switch" for $170+.

I was thinking that the clutch sensor that is tied into the cruise control might be the one that is bad since the cruise control went out.

I'm having trouble locating the neutral safety switch, I think I've found the one on the underside of the car, if you are laying under the cars engine head towards the rear its on the right correct? Well IF this is the one I need to remove/replace I don't see how to go about removing it.

Since my car is a manual I'm guessing this is not the part I need?

http://www.partsgeek.com/jbq4q5c-ma...ag&fp=pp&utm_term=Mazda+Neutral+Safety+Switch

Can someone link the part for the manuel?

Thanks PCB

This is looking more promising.... Is this right?

http://m.autozone.com/batteries-sta...nders-2-0l-mfi-dohc/349698_676193_0?location=

I still believe that there is no other reason for my cruise control to be out besides that somewhere down the line from where it is attached to the clutch/neutral safety switch has gone bad.

You should really test your neutral switch before replacing it.... You don't want to just throw parts at it.

There's a good chance it's just a bad/broken connection.

CBrn42 said:

This is looking more promising.... Is this right?

http://m.autozone.com/batteries-sta...nders-2-0l-mfi-dohc/349698_676193_0?location=

.

Click to expand...

That looks like the right one...

Remember, there's two switches connected to the transmission... The other is a reverse switch.

You may have to drain your transmission fluid to replace it. (you have to for at least one of the switches... I forget which one)

If you do, loosen the oil fill hole first before draining it to make sure you can get it off.

I've seen a disconnected neutral switch cause a Miata to idle and run very strangely.

There are also two switches on the clutch. One disengages the Cruise when you depress the clutch, the other prevents the engine from starting with it released.

The switches in the transmission are easy to test. Just depress the ball and see if it opens or closes the contacts. Test with a headlight bulb or something to make sure it can carry a load as well.

So I bought that part I listed, the second one, and it was the one for the reverse light, so I threw it in and then took the old reverse light sensor, cut the connector off and spliced on the connector for the neutral safety. Ended up with some transmission fluid on the ground and not getting any closer to fixing my issue because I don't know if we replaced a working switch with a working switch and it was always another problem, or we either screwed up the splicing or the problem is in the wiring further up past the actual sensor.

Anyhow it's not that I'm not listening to you guys it's just that I'm timid about working with wires/sensors/car-computers because I've never even checked a wire for continuity before, closest I've ever gotten was licking a battery as a kid to see if it was good or not. I'd have to watch a YouTube video on how to test continuity and go buy the tools (I know I should anyway and I will soon than later)

Here is a video I uploaded to YouTube on the idle problems. Notice the high idle from start and I then drive around the block in my neighborhood until the car warms up and the idle starts fluctuating. I suggest skipping to the end of the video to see the fluctuating.

https://youtu.be/VWZzC-HeowU

It's really easy to test your neutral switch.

Get a multimeter and set it to ohms.

With the ignition off, unplug the neutral safety switch and touch one probe to one of the terminals in the connector coming front the switch itself and the other probe to the remaining terminal in the connector. (positive and negative (black or red) doesn't matter).

You should get either zero ohms (or close to it) or infinity... It might show O l for open line.

Then put your car in gear (or out of gear) and you should see it switch to zero ohms or infinity.

It's the switching you want to see.

If you don't see the switching then your switch is bad.

Using a reverse switch for a neutral switch may not work... They could have different dimensions and not reach far enough or something but you can tell by the in and out of gear test.

Your ECU probably disabled your cruise control because of the bad neutral circuit.


If your switch is switching then you have a problem with your wiring for it.

That too is relatively easy to fix. Splice a wire from your switch directly to the ECU, bypassing the original harness completely.

Cut the wire going into the ECU about six inches back from the big connector at the ECU and splice it in there.

It's possible the connectors are not in the right place. A friend had the same problem after an engine swap, the neutral switch was connected to a connector on the side of the head that is supposed to go to a capacitor for the ignition coils. Swapped the connectors and it fixed the problem. Post some pictures of where the connectors are hooked up.

Here's the wiring diagram for the neutral switch.

The input for the switch is a pink wire with a green stripe.

It changes color to black with a blue stripe by the time it gets to the switch.

The second wire from the switch can ground anywhere at the ECU under a bolt or with another ground wire.