GeoPrizm : check engine light?


Hello Guys, I have a 97 Geo Prizm with low miles 59K. The check engine light goes off every once in a while. First time it happened a friend of mine who is car mechanics savy looked at it and changed the 15 amp fuse (which had gone bad, later I found out the socket had melted a little as well). After that when check engine light goes off , I just change the fuse and it works. Sometimes when the light goes off the car still works fine .Other times it wont start and thats how I know the fuse needs changed. I took it to a Chevy dealer and he said the fuse box needs changed, toyota dealer said take it to chevy dealer. A local mechanic looked at it and said changing the fuse box may not fix it as the problem may be inside the wiring or some connection causing an overload. He said why dont you just keep changing the fuse as its not expesnive (5 for $2). I did that for 2 years. Recently took it to one of the Pepboys and first they said 'the master mechanic couldnt find any problem on the surface inspection and they would need a diagnostic check which will cost $90. I paid for that but still they couldnt pinpoint anything. They said either the fuse box needs changed or they will by pass the wiring and put it another socket in the same box. either way the job will cost me $600-800. I just came back. Its an old car but runs great, has low miles. I tried to sell it but when ever I mentioned this problem it scared people away. I dont mind keep changing the fuse for now but eventually would like to sell it. Plus its a little problematic changing fuse every 2-3 weeks, specially now that winter is coming. Any comments ? suggestions? mechanic that you would recommend? (pittsburgh area)


It is likely that the problem is not in the fusebox but in one of the components controlled by that particular fuse. If this guess is correct, then replacing the fusebox or bypassing the fuse’s socket will fix nothing. You won’t correct this problem until you locate the mischievous component. This would be a time-consuming task, especially so if the problem is intermittent, which it seems to be.

My recommendation, probably not what you want to hear, is to continue try to find a buyer. Your conscience dictates you must inform them of this problem, of ocurse, but you need not do so at the very start. Wait until you have good interest and then mention it, along with their free year’s supply of fuses you keep in the glove box.

It is indeed possible that this car may go through a succession of future owners and it may never have the problem completely resolved throughout its lifespan. Good luck, my friend. Let us know.


Thanks Steve. Thats something I thought about too. I will let you guyz know how it turns out.


There can’t be that many components on a 15 amp fuse. Why not reveal who the mystery fuse is? Someone may have an idea of a fix.


I sure would like to know too. The Chevy dealer , Toyota dealer, Pepboys and a mechanic couldnt figure out. I also get a feeling these guyz never really looked into it or put much thought in the first place. The ones who gave huge estimates to fix it probably gave the worst case scenario and would have worked their way down. Its so common for everyone to get a new car and dump the old one. The culture of figuring out problems and trying to fix it is gone. I’m disappointed.


Even the toyota or chevy dealer said we will put the car on ‘diagnostic test’ that will cost couple of hundred bucks. Its like going to the doctor and saying I have a problem and the doctor replying “go get this xray/tests then come to me” ,without even looking at me first. Thats just great!


YOU changed the fuse several times. Don’t you know the position name, or number, of the fuse you changed?! We need more than, “a fuse was changed”.


15 amp fuse, blue colored. I mentioned that in the first posting, may be you missed it. (2nd line)


Looking at a Power Distribution schematics I’m finding only 4 diffrent 15 amp fuses. They are EFI and F-HTR Fuse, Stop Fuse, Tail Fuse and A/C Fuse. Of the four 15amp fuses the only one I think would set a CEL or stop the car from starting is the EFI and F-HTR Fuse. Check for loose connection at relays and all connections powered by this fuse. I would also check for good ground connection. Could also be bad contacts inside of relays and also a fan that may be drawing higher amps than normal.

Hope someone did’nt install a greater size fuse than normal. If they did then the above info may be incorrect.

If you bypass the current fuse box with another fuse assembly all that would happen is this new fuse would blow. Need to locate what is drawing the higher amperage on this circuit.

As hellokit says we need to know where in the fuse box this fuse is located, car makers normally number the location if not on the fuse box then if you have an owners manuel it will show the number as will as what circut it is protecting. You can also get the info we need from most repair manuels.

Did I miss it or has no one checked the CEL?    That CEL (check engine light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code not just their translation into English and post it back here. 

Fuses don’t generally “go bad” Fuses blow protecting a circuit because there is a short on the circuit and it is preventing additional damage. As you have noticed replacing fuses that are just doing what they are suppose to do will not fix the problem be cause the problem is not the fuse.

It is very possible that the CEL code will point to the problem. Other than that, we need to know what circuit that fuse protects, because something on that circuit is having a problem and needs help.


Its the 15 amp EFI fuse. Any thoughts ? Recommendations? Thanks.