Guages Not Working

[Yamaha74]

I just purchased a truck that has a 1984 cab and 1978 3/4 ton frame and drive train I believe.  I say it is a 1978 because the Tcase is labeled as 1978.  This is a 4x4 with a 350 motor (I think as I am still trying to identify it), TH350 Tranny, and a 203 Tcase.

None of the factory guages are working or the lights that light up the guages.  It does have a aftermarket oil pressure guage which does work and coolant temperature guage but I am not sure it works.  Where should I start diagnosing the problem?  I would at least like to get the speedo and fuel guage working.  I know there are electrical diagrams out there but I am not good at reading them.  Is the speedo and fuel guage easy to hook up?  Any advise would be greatly appreciated.  At this point I do not want to buy aftermarket guages and was hoping to attempt to getting the factory guages working.

My radio also doesnt work.  It is an aftermarket radio.

[VileZambonie]

Fuses are OK? Judging by nothing working and having aftermarket gauges it's probably not plugged in.

[Yamaha74]

Not sure about the fuses.  I haven't really dug into it yet but since I am pretty electrical illiterate I wanted to get an idea of where to start.  How can I tell if it is plugged in?  I assume you are talking about the fuse box.

[howlinwolf]

my fuel guage doesnt work, but the sending unit is bad. If you ground out the wire at the sending unit, it should read WWaaayyyy full if im not mistaken.  is the speedo manually driven or electronic.  if the speedo isnt working, check the speedo connections, and if they are hooked up, then the cable is probably broken.

[Captkaos]

Pull the INT fuse out and see if it is blown, is anything else not working or does everything else work?

[Yamaha74]

The guage lights do not work.  The stereo doesn't work.  The turn signals are acting a little wierd.  When I turn the left one on I think they both come on and if I turn the right one on I think it comes on by itself.  The horn doesn't work.  The only thing that works for sure is the oil pressure guage which is an aftermarket one mounted in a seperate location.  There is a aftermarket temp guage that I am not sure is working. 

For the speedo, I keep seeing people mentioning that the cable goes to the transmission.  Is that the case for all these trucks?  If that is the case is it a pretty simple fix as long as the guage actually works.  I assume the speedo is manually as they are the factory gauges from 1984.

[howlinwolf]

im unsure of 84 but the 78 is that way.  you may have a ground that isnt correct. power feeds back through other circuits and makes funny suff happen, or things not even work.

try grounding out the connecter at the fuel sending unit and see if the guage moves.

[Captkaos]

If you blinkers are coming on without blinking you have a bad bulb or ground.
84 trucks had all electrical gauges EXCEPT the speedo which is mechanical.

[Yamaha74]

Ok thanks for the info and hopefully this weekend I can dig into the dash and figure out what is going on.  I guess if I get in there and determine that I have a mess on my hands and that I should just start over with the wiring I will be probably in the market for a wiring harness.  I did a little research on this site last night and it looks like the EZ wiring might be my best option.  With my the body of my truck all being a 1984 and the drivetrain and frame being from I believe a 1978 will I have any issues with one of the EZ wiring harnesses?  Also, which harness should I go with since my truck doesn't have power windors, door locks, cruise control, and AC.  I am leaning towards the 12 circuit standard, but it doesnt seem to have a circuit for the dome light and cigarette lighter.  I am not sure if I even have a cigarette lighter.

[ToddN]

When I bought my K10 NOTHING on the dash worked.  It only took a little investigating and tinkering and now everything works.  My coolant sensor in the block was shot.  That was 10 bucks.  The ground to the oil pressure was rusty.  I wire brushed that and its fixed.  The speedpmeter came unclipped and just needed to be hooked back up.  Same with the gas guage.  I took it out of the dash, tapped on it a little...plugged it back in and it's worked for two years.  Replced bulbs with blue ones and thats it.  Sometimes it isnt a cluster-you know what.  Sometimes its just generak maintenance that has been neglected.

[bobcooter]

Fuses are OK? Judging by nothing working and having aftermarket gauges it's probably not plugged in.

Pull the INT fuse out and see if it is blown, is anything else not working or does everything else work?

Always start with the simple things first and then move to the more complicated things. It will save you a lot of time, headaches and money.