check engine light for no obvious reason

[chris_wei17]

I've looked for anything that can point me in the right direction, but all I've found is that the yellow light with the words "check engine" means either the oil pressure is low or the coolant temp is too high. My problem is that my oil is topped off and the coolant in the resevoir hasn't gone down. No I dont have real oil pressure or coolant temp gauges and yes I'm getting there, but right now it doesnt seem like either of those should be tripping the light. The light comes on as soon as I start the engine which makes me think the circuit that the light is on grounded out or something bc even in this heat it shouldnt be overheating before its running. The only thing I can think of is that the cooling system might have a leak and instead of sucking in coolant from the resevoir when it needs more that its just sucking in air through the leak. when I pull the radiator cap off when the truck is cold are you supposed to be able to see fluid in there? short of draining it I'm not sure how to see how much is actually in there and I havent had a chance to drain it yet. The temp gauge was *working* but now either is bottomed out like its off or way towards the cold end of "NORMAL". it's starting to tie my brain up in a pretzel, any help would be appreciated

 

[riotwarrior]

bad coolant over temp sensor in engine can cause this.

 

[dsltech83]

Being a 94, is your truck a powerstroke? Idi's don't have a yellow check engine light. We have a red engine light that comes on in a overheat or no oil pressure situation.

 

[icanfixall]

Both posts above are hitting on something that might be your issues. Please try to answer the second question. Now if you actually have the idi and not the power stroke engine do this. Find the front of the drivers side head. Lift that wire from the sender. See if the dash lite goes out. If it does then your sender is bad.

 

[chris_wei17]

It is an IDI, I had to put in a new cluster because the speedo didn't work. Long story short theres a circuit missing from the one I put in that doesn't let the voltage regulator switch in and charge the batteries. So I put the old cluster back in and just put the newer speedo in, it was from a 97 I think, but either way it's been set up like this without the light coming on for a while so I don't think that frankencluster is the problem, the light that's coming on is to the bottom right of the tach, I think that red light is on the bottom left side of the bezel around everything if I remember what I read right. Ill check that sender and see what happens, I'm assuming its just two wires right?

 

[TronDD]

My problem is that my oil is topped off and the coolant in the resevoir hasn't gone down. when I pull the radiator cap off when the truck is cold are you supposed to be able to see fluid in there?

Your oil being topped off and you coolant reservoir having coolant has nothing to do with oil pressure or coolant temperature.

And, yes, if you open the radiator cap, you should see the coolant very near the top of the radiator.

Tim.

 

[chris_wei17]

By that I mostly meant that it didn't seem like I was loosing any so I assumed atleast oil pressure had to be good. Thanks for the fill level tip though