Well I was driving Zed the other day and suddenly was horrified to see my tach was sticking. Wasting no time I pulled over (actually to grab a gyro) and turned the beast off. The car has 1600 mi on it.

When I returned the tach was behaving properly and has been doing so ever since. This was about a week ago. It's not cold here and it was about 75 at the time.

I expected it to get worse, but it hasn't shown up again.

Anyone have this problem? Any ideas what's going on?

Z-Stalker

 

There was a thread on some forum 2-3 months ago on this topic. 'Don't remember where I saw it.

It was only happening to roadsters, not coupes.

Never heard of an absolute solution but the consensus was that the sun was shining from behind the car and was somehow interfering with a photocell or some other form of optics in the Tach or Speedo. (if I recall,it was happening in both instruments - but not both at the same time) Only happened when the sun was low - either early or late in the day.

Several people experimented by blocking the sun with their hands, etc and it seemed to prove the theory.

Like I said, I never heard of an absolute answer but the above seems to be a pretty good guess.

 

Very interesting, never seen any talk on this before. I would say if it hasn't happened before not to worry about it cause if you can't reproduce it, there is no way a dealer will be able to. I would try what Penderwheels mentioned about blocking the sun if it happens again.

 

Ahh! This has happened to me twice in the nine months that I've owned my roadster. Now that I reflect back, it occured early morning the first time and late afternoon the second. Both times, the tach started working again when I changed directions.

Thanks for the explanation.

 

The original thread starter was myself. The theory holds true.

Since my original post other Roadster owners have been experiencing the same issue.

When the sun comes up in the east or is setting in the west, and the gauge needles are exposed to direct sunlight, they will freeze in place, and will not unfreeze until you change direction or shade the gauge needle from the sun. When you shade the needle it will begin to work again. The response is immediate. Either heat or light is creating the problem. I tend to lean to it being a heat issue. Most gauges use a small delicate coil spring. I believe this spring is expanding from the heat and freezing the needle in place.

I stumbled onto this one day when I decided to adjust my steering wheel to see if there was a more comfortable position. The Tach was now working but the speedo was now freezing in place. I noticed the top of my steering wheel was now shading the Tach needle but the Speedo was now exposed to the sun. I shaded the Speedo and it worked, I moved my hand away and it froze, I did this all the way home. It was not my wiring, it was not the Gauges, it was in fact the sun.

Hope that helps

 

Cursed sun...

I'm in SW FL and the time was about noon about 78 degrees which leads me to believe it's a heat issue.

Thanks for the responses. Now I can rest a little easier knowing what's causing it.

Z-Stalker

 

hmm, maybe it sticks because it hits the gauges? When i took my gauges apart, the needle would sometimes stick when i didn't have the cover in place all the way, hence, the gauges were falling on top of the needles. Once i put everything in place and clamped everything together, the gauges worked as usual.
If you are brave enough to take your cluster apart you can check it out.

 

Mark me down for once also. Top down mid afternoon, sun at my back...looked down and tach was "stuck" ....just long enough for me to think "got to go back to the dealership and have some grease monkey that failed high school red line my ride....I DON"T THINK SO !!!!!!3 minutes later back to normal...no problem since

 

Any 05 experience this?

 

I've loved to try it for you but here in Seattle I haven't seen sun since I bought the Z. Sounds funny but that's true, we got to much freaking rain and clouds all the time .

 

While I certainly don't doubt any of you roadster owners, that makes no sense whatsoever. Let's say that the sun hitting the guages caused a 5-degree temperatures increase in whatever mechanical device actually started binding. What happens when the entire car reaches that temperature when the windows and top are up, or even exceeds it by 10-20 degrees? The guage should be stuck permanently then until you get the car cooled down. I buy the symptom, but I have a hard time with the prognosis. That just doesn't make sense.

Where's all of our engineers and scientists...Someone must have a different theory on this.

 

The different theory was they are like some of the newer gauges out there, where they use optics to communicate where the needle should be at any given time. The light from the sun is shining into the gauge cluster at just the right angle to interfere with the process.

Either way, it doesn't much matter. The sun is still the culprit of the malfunction. This has been proven time and time again by many ZR owners. Once they knew what to look for. I don't see that changing regardless of the exact scientific reasoning behind it.