So one of the weirdest things that ever gone wrong with my car is upon me. First off, the other day i was driving along and all the sudden my speedometer dropped down to zero. I revved and sped up/slowed down and nothing happened, until i hit the brake. As soon as i hit the brake, the speedometer shot right back up to where it was supposed to be, then as soon as i let off the brake it went right backdwon to zero. Eventually after driving for a little bit the needle started going up on its own, then would falter and fall down 5 or 10 mph, then go back up, and evnetullay after hesitating it made its way back up to normal.

This problem stopped yesterday, but now it seems it has moved onto my tachometer signal. I dont have a tach, but i have shift light. Its adjustable, and its been the same for a while so i know when it should turn on.I started my car today, and if any of you have a shift light, you know it lights up when you first turn the car on, kind of like a test. Well it did that, but then when i was driving it wouldnt turn on at the correct time. I had to rev REALLY high to get it to work, and even then it would just flicker. And also sometimes it would randomly flicker wehn my RPMs were at a constant. Then i thought about the brakes thing, so as i was driving along i pushed the clutch and the gasinto make it rev really high and quickly tapped the brake, and sure enough, the shift light came on exactly like it was supposed to.

I'm thinking this has something to do with the signal being sent from ECU, not really the speedometer/cluster or the shift light themselves. Anyone know any fixes, or do i need to take it to a shop?

PS thanks for reading all that

 

that could be 2 separate problems.
could be the sensor on the transmission, and a tach (shift light) problem.
cant much help since i have an 88.
speed sensor on the trans is mentioned here a lot. dont know how that is troubleshooted.
thought the tach got its signal off the coil (but maybe it goes thru the ecu - although i dont think so)

 

it could go thhrough the coil, maybe ECU wasnt the best word choice, just wherever it gets it signal from is what i meant.

i dont really think its the shift light becasue my OEM speedometer had the same exact problem, so i'm thiking its something with the signal

 

I have a friend with a prelude having the same problem, I would like to provide him with a logical answer as well. It seems like wiring to me, but I agree it might be a sensor, or ECU issue.

Hope someone can solve it, I am interested.

 

My speedo had that problem. It gradually got worse as time went along. It got to a point to where it just stopped working and said I was always going 25-30 mph. I took it to a shop to test the gauge bezel. They said it was fine. I let then replace a "bad" speedo sensor and then a "bad" nylon gear that is somwhere in the transmition. Neither of those things fixed the problem. It turned out that I was right and that the stupid guage was bad. The chances that the sesnor, gear, and gauge were all bad are slim to none. Needless to saw don't go to Weissman Auto Repair. They will kindly take your money, but that's all that they do.

 

i understand - but those are 2 separate signals (at least i think)

 

anyone?

 

This makes methinking about wiring. Especially ground in instrument cluster area. Or bad cluster itself - I don't remember exactly, but I beleive brake lights circuit goes through cluster...

 

Just get that SI or Ex cluster that you have always wanted, that will fix it right there most likely... did for me anyway

 

yeah i'm thinking i should Tim, or maybe just anotehr DX one since that's cheaeper and i'm planning on getting a triple piller pod w/ a tach on it anyway. It sure seems like the brake would go through the cluster becasue its odd that both the tach and the speedo signal are affected when i hit the brakes. Still having the tach problem, buts sometimes it works perfectly and other times it randomly flickers on and off.