Hey everyone, I am new to the forum, but I have been poking around here for about a month since I bought an 84 2m4 4speed. I have finally decided to create an account on here and post as the internet has largely failed me in most of the work I have put into this car.
My current problem: Most of the gauges do not work. The tachometer doesn't really respond well, the fuel gauge is stuck on empty despite filling the tank (that's why I filled it, cuz it was stuck on empty and I didn't know it) and the odometer does not read. I have driven around at least 5 miles and it does not move. I have removed the cluster and completely disassembled the whole unit and put it back together and still nothing. Fuses seem to be good and the car drives pretty well. it's an "85" speed gauge.
I am at a loss. The simplest solution is often the correct one. I doubt all the different aspects of the car that make these individual components could ALL be malfunctioning, so it's got to be the cluster itself right? If so, what could be the problem? Has anyone else experienced this?
I am hoping a guru on 84s will post something, because they are somewhat different than other years, but I would suspect the printed circuit sheet in the gauge cluster. They have de-laminated over time and are difficult to trouble shoot. Often the contact points wear out.
I don't know if my 87 GT gauges are similar or not, but i had a similar issue a couple weeks ago. Take the screws out of the cover on the dash above the gauges to get to the connections on the back of the gauge pod. They are know to get corrosion on the "circuit board" connections where the plug clips on the dash. It is on the right side (sitting in the car). unclip it and look at the connections to see if there is corrosion. When i checked mine, there was no corrosion, but the plug was not clipped on the board properly. Give that a go and let us know. troy
Did the problems start at the same time? If so then they are most likely all related, possibly a bad connection or ground connection. If separate then I would start with one of the problems and start troubleshooting it. If it were me I would probably start with the gas gauge.
Odometer do fail completely.
Tachometer- does the engine run well when the gauge is acting up?
Fuel gauge- There are 3 wires going to the fuel tank -- Ground, Fuel pump power, and the Fuel gauge sender wire. The sender in the tank is just a variable resistor, which should read 0 ohms when the tank is empty, and 90 ohms when it is full (measured between the sender wire and ground). If your gauge is always pegged empty with all wires connected, it means that the sender itself, or the wire leading to it, is shorted to ground.
I don't know if my 87 GT gauges are similar or not, but i had a similar issue a couple weeks ago. Take the screws out of the cover on the dash above the gauges to get to the connections on the back of the gauge pod. They are know to get corrosion on the "circuit board" connections where the plug clips on the dash. It is on the right side (sitting in the car). unclip it and look at the connections to see if there is corrosion. When i checked mine, there was no corrosion, but the plug was not clipped on the board properly. Give that a go and let us know. troy
I've disconnected it and reattached it several times. I don't really know if all the problems started at once. I didn't notice the odometer until I had been driving it around.
I have an operating permit for october. I'd like to have this problem fixed before the end of the month so I can have it smogged and officially registered.
I wouldn't be surprised if these are three independent failures. I agree with Ken. Start with a single gauge (preferably the gas gauge) and troubleshoot that. If you follow a systematic troubleshooting approach on the one gauge and it turns out to be a common problem then so much the better. Ken wrote a good test procedure for the gas gauge that will help you determine if the problem is with the sender or not. Sender failures are very common on Fiero's...especially ones that sit for any length of time.
Okay lets say it is 3 separate problems. The gas tank is full and I am not interested in draining it to find the problem. Lets start with the odometer since that is the most important part. Any ideas on where to begin?
While may be possible to troubleshoot an odometer I don't think I would. I think it would be easiest to swap the assembly with a used one and see what happens.
Finally got around to plugging in my other gauge cluster and the odometer started rolling when I drove it around. So I guess it's a mixed bag of problems.
Odometer and trip miler are driven with stepper motors on the speedo board. In Canada the sticker on the back is blue and will spin the numbers in kilometers, in the US it's black and will spin them slower in miles. And they fail. Ask me how I know. On a bright note other GM cars of the vintage also used the same stepper motors - think replacement parts.
GM fuel sender units do fail - the resistor breaks, dirty gummy resistor surface, sloppy contact or a buggered wire to the tank.
Your tach failure has me stumped. You need to get the wiring diags and trace the tach input and ground connections. The EMC also uses the tach signal and if the engine has no apparent issues, look for wiring to and from the tach.
I realize this is not much help, but you get what you pay for or what I know and memory fails.
