All,

I just bought a 1984,, I have a major problem.. When I first start the car, the dash lights do their normal thing... however once it starts, the dash is lit but no gauges or speedo or tach work...

I am at a loss here,, Where do I start,, I already checked the grounds,, I cut ground off dash,, everything went off, then I spliced to grount to battery,, everything came back on. like it was.

When my volts are low or the car is hot... it shows the temp or volts or oil pressure... but when everything is running right.. nothing on dash shows,,,

I need to figure this out,, any help is appreciated..

 

I have read about those era dash's going out. You may need a rebuilt cluster.

 

it sounds like the display self test functions. That is what's going on. it sounds like the information is getting lost in the dash cluster. the info might be getting into the dash, or a connector has loosened up and is no longer connected. The thing to do is change the resistance on each parameter.
for instance, go to the temp sensor under the hood, and ground the temp wire. it should change to either max or min temp do the ssame for the other parameters, except mileage won't work since it comes from tht computer.

 

Ok,

Can someone give me more details on how to check all of this... I usually just wirte checks,, and dont do the work..

 

usually the units tied to the computer are based on resistance. when you vary the resistance on the engine sensor, the dash changes. for instance, if you take the temp sensor wire off the head sensor, it's the one in the front left (I think, I have an 86 and mine's in the back right) if you stick a paperclip (straightened out) in the wire, and put the other end to the paper clip on metal of the engine, you have just grounded the wire. If you use a wire with clips, you can clip one end of the clip wire to the engine, and the other to the paper clip stuck in the engine harness wire. then go look at the gauge. it should have changed. If that doesn't work, pick another wire like the oil pressure. that is back by the distributor. it's the round bulbish looking thing with one wire on it. take the wire off, and as before, put the paper clip in the connector wire from the engine harness, and put the paper clip to the engine metal. then go look at oil pressure.
if you only work with the ones that have one wire, you can't break anything. The ones with the one wire are all looking for the sensor (screwed into the engine metal) to give some value of groundness (new word I believe) to the gauge. you are giving it full ground, and that usually gives a max value to the gauge. for instance, the oil pressure might read 200 or the temp gauge reads 500 or maybe 888. whatever the gauge is calibrated to read at max value is what you will get. I had a problem with my temp a while back, and grounded the temp gauge, and it read 300. not sure what the 84 readout will go to since I never had one.