RallyOwner

First off, let me say hello to everyone, this is my first post, as a matter of fact, I just found this message board about an hour ago, I am so excited, a wealth of information.

I just bought a 90 camaro rs with a 305 tbi and 700r4 trans. it's all stock except for the exhaust work thus far(couldn't handle the quiet stock system). I bought the car to drive while I restore my rally nova, and the more I drive the more I love it, and it has slowly turned from a car to get me by to a car I want to fix up(this happens a lot to me, lol).

Anyway, I usually stay away from "newer" cars, cause I know how to work on the older cars, and all this computer stuff is confusing to a shade tree mechanic like me. So I have gone over the car and fixed all the little things to make it reliable, and now there are some things I want to fix just for my own sanity.

My tach doesn't work, it just "pegs out" all the time, except for a moment when the car is starting. If I attempt the start the car, but it doesn't immediately start(like a cold morning) the tach will fall to zero, but then as soon as it starts, it goes past 7k until it can't travel any farther, and doesn't move until I start the car again. When the car starts quick like it should, the tach jumps up to 4k for a split second, then pegs out again. This is killing me, and I don't know where to start.

I got a manual, and looked at the wiring diagram, but according to the manual the car has a hei ignition, but it doesn't look like the same I have in my older cars. On the older cars, the tach wire plugs into the side of the dist. cap along with all the other wires, but the camaro's dist. cap doesn't have this little plug so I can't trace down the tach wire(I figure it's a short some where causing the tach to read wide open all the time).

There are some other "wiring" problems as well. The dome light doesn't work at all, tested it and it is getting no juice, no matter what I do, even turning the light switch all the way up doesn't allow it come on. The lighter doesn't work, and the lights are stuck on bright all the time, the dimmer switch doesn't seem to work, when you pull on it, it has some resistance, but it doesn't "click".

I know that the above problems sound like a fuse, but I checked them all, and they were good, so I don't know. My biggest problem is the tach, please if anyone can help I would appreciate it. I am off to search the boards to see if the question has come up before(did a small search and couldn't find anything).

RallyOwner

Thought I would stop by and see if anyone had any information for me, and to say that I figured out why the dome light and other things didn't work. Turns out the fuse was bad. When I checked them, I did it visually, and I suppose that wasn't good enough cause when I went back and checked everything with a tester, the fuse turned out to be bad.

The fuse still looked good, I couldn't see anything wrong with it, but it wasn't letting the juice through. Now, I have a dome light, door locks, horn, and cigarette lighter, those are quite a few things that I have done a lot of tracing to find, man I wish I had checked the fuses better when I first got the car, it would have saved a lot of time and effort.

The tach still doesn't work, I didn't think the fuse would have anything to do with it, but I sure was hoping it would, I really need some help with this, can anyone just tell me where the tach wire is under the hood, or where all the wires plug into the distributor? I think that I have found out why the dist. caps are different from older chevies. The HEI's that I am used to dealing with are the coil in cap kind, and I think the camaro's coil isn't in the cap, maybe a newer design, if I could find the coil, and all the wires going to it, I think I could fix it. So if anyone can help me, it would be great.

If I finally do chase the wire down, and can't find a short, the only other things it could be is something in the cluster, or the tach itself right? I may take everything apart this weekend to install the new glow gauges I got off ebay, white during the day, but they have the "indiglow" look at night, I just wanted to brighten the dash panel up. So while I have everything apart, I can check it out and see whats up. I hope it's under the hood though, I feel more at home there then in the dash with wires and relay's galore.

Trickster

Welcome to the group RallyOwner,

Here is a picture of a HEI distributor with the coil in the cap. There is something like a leg or extension coming off the back of the distributor cap. This is where the connection for your tachometer is, there is a four wire connector at the base of the cap on the distributor that connects inside this extension. Hope you can read this picture.

deadbird

Welcome to the boards

The distributor is still HEI but, not in the traditional style you're probably used to. Just as a cap-in-coil HEI, the tach still reads the pulses from the coil. There should be a white wire on your coil, that is your tach lead.
This problem pops up occationally and from what I remember, there is a tach filter w/in the distributor (capacitor or condensor.. I can't recall which) that occationally fails or, the tach itself is just bad.

Using the search may help you find a better answer as well.

RallyOwner

The HEI pictured above is what I am used to. The one that is on the camaro isn't like that. I figured the coil should be mounted close to the cap, but I can't seem to find it, does anyone know where it is mounted?

From what I have read using the search on this board, it seems as though these years have more problems with the tach, so at least I am not alone. After I trace down where the coil is, and check the tach wire, I may just go to a local junkyard and see if they have anything I can get the cluster out of, and hopefully that will fix it. Does anyone know of a way to test the tach that is in the car once it is out?

Thanks for all the info, and for the warm welcome, this is a great board!

Trickster

The coil is mounted at the rear of the engine on the passenger side about 8 - 10 inches from the distributor. Here is a picture of it.

RallyOwner

Thanks! Not even close to what I was looking for, that picture helps me out a lot! Where do you get these pictures from? I will go out and hunt it down asap to see what is up. I finally know what it looks like, but we had a big snow last night, wouldn't you know. Again thanks for everyone's help!

Trickster

You're welcome, I get the pictures from the GM service manual for my car.

Fairly Strange

He-he welcome Rallyowner, I can relate! I'm an old car buff, myself....for the same reasons.

If it hadn't been for a bit of electronics training back in my teen years I'd have never guessed that would be the coil!LOL

These things aren't quite as big a PITA as you think, and the fun part is the computer will diagnose quite a few(NOT ALL!!!) of any problems you might have.

So far, my biggest headache has been figureing out what the "alphabet" is. Seems every sensor has its' own list of letters that it is known by.....but that don't help you to understand what they are, where they are or what they do.

This nice bunch around here are very good at explaining these things. I must admit, they have been more than patient with my stupid questions.

Without them, my stepdaughters' '89 Formula would still be hopelessly parked in the garage.

Good luck and have fun! I'm still trying to figure out how to use some of the techno stuff on my '65 Valiant!

HeavyBreathinRS

Trickster has the location down perfectly...as always :hail:

You can just follow the HT lead from the centre pin of your distributor...it goes directly to the coil...no passing go, no collecting $200 etc...

RallyOwner

Ok, finally had the time to check the location of the coil. Turns out it was mounted right in front of the dist! It was hidden under the air filter assembly. Anyway, seems like I remember reading somewhere that the white wire was for the tach. it was plugged into where the number "2" is in the above picture.

It appeared to be connected cleanly, and in good shape. I traced it as far as I could and it looked fine, I moved it as much as I could just hoping that it would move the wire enough to work(if that is what the problem is to begin with).

Fired the car up, and past 7k instantly, man that sucks! So my only guess is that it's the cluster or the tach itself, especially if you consider the fact these cars seem to have faulty tachs to begin with.

I notice that ebay seems to have entire clusters, and tachs individually. Which should I buy? I am thinking the whole cluster would be easier in the long run, besides it would let me install the white face gauges and led gauge lights easier. Anyone on the board have a cluster they want to part with?

I thought I would send a pic of the camaro, it's not much now, but I am working on it, I have the headliner out right now recovering it, and much more interior work to come.

Kontrax

you could go aftermarket to save the pain of wiring in a whole new cluster. you could also get an MSD box. the tac plugs right into the side of the box. i have mine mounted on the inside of the car to avoid heat/water damage. i myself hate the wiring and all the electronics of the new cars myself. thus the reason i swapped back to carb. looks like old school muscle engine now, removed all the wiring and computer

classic industries offers a GM tac with the bowtie on it that will replace your stock tac but its like 120+ shipping. if i was sticking with the stock looking cluster i would go for that tac