CASIS light behaving erratically

[Majariwr]

I've read many of the CASIS light threads, but haven't seen this issue yet. I just installed a new (to me) used tach (face on my old one was marred by a radar detector readout). Needle works fine, but CASIS light flashes randomly. The CASIS light worked the way it should in the old tach, but new tach is a bit random. I'll likely end up disabling it either by removing the black wire at the back of the tach, or just removing the bulb, but if there's an easy fix t get it working properly, I'd prefer that. Ideas?

[Majariwr]

Just remembered from looking at the back of the tach that the bulb must be inside and removal requires taking the tach apart. It is not one of the 5 bulbs accessible from the outside. So disconnecting the blac wire seems to be the only option.

[GH85Carrera]

Like many of the members of the forum I always hated that stupid light. I know when to shift, and I am not trying to save gas, I am driving for fun.

I just replaced mine with something useful, a volt meter. They shift light is just a silly thing the 1980s US government foisted on all car manufacturers of the era. All cars had to have some way to show you how to save gasoline. At least we did not get the dumb vacuum gauge.

I know you did not ask about how to replace the light, but unless you are into 100% original cars, why bother?

An blinking light almost has to be a bad connection. The light is controlled by the DME and only needs 12 volts and a ground.

[Majariwr]

Thanks. Cleaned the contacts but same behavior. Maybe normal but it always seems to want to shift to higher gear, no matter how slow. Doesn’t turn off even when coasting. Can make it turn off by stepping on it, as it should. And turns off in 5th. Maybe it’s normal, but just seems to be on more than the old tach.

[GH85Carrera]

That is about normal. Only under a decent load in the lower gears does it figure it is OK to stay in the same gear, so like going up a hill with more throttle needed to keep going, it should turn off.

Most everyone hates the silly thing. I am happy I got rid of it many years ago.

[john walker's workshop]

Black wirectomy.

[Majariwr]

Black wire-ectomy didn’t work! The light is still behaving erratically. Real question is what did I do by clipping that wire? Car seems to run ok, but maybe not that simple?

[darrin]

HMMM - post black wire-ectomy, my CASIS light sill illuminates when I hit redline -- suggesting the light's triggered by more than the black wire. Sounds like your replacement tach may have some issues

[Majariwr]

Yes, that’s what I was thinking too. Definitely more than just the redline. Behaved the same pre- and post-ectomy. Next move might be to just swap the gauge face from the replacement tach with face from original. Not really looking forward to trying to open up the tach and remove the needles. Any trick to this other than extreme patience?