93 Buick regal with 3800 keeps blowing EMC fuse in engine conpartment - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 06-02-2016, 11:45 AM   #1
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Default 93 Buick regal with 3800 keeps blowing EMC fuse in engine conpartment

I ave a problem where when i have my 93 Buick regal running it blows the 20amp ECM fuse under the hood, My cooling fans run all the time on high speed I had a code of 69 in the ECM I tried unplugging the a/c comp clutch, & the low & high PSI sensors the fans keep running I replaced the ECM after trying to unplug the crank sensor & coils & still would blow the fuse when cranking over the engine. I was a auto tech before but this kind of problem was not my strong point. My A/C was not working at one point until I had to replace the harmonic balancer because the rubber had torn apart& it was making noise that was about a month ago & the A/C had started working again I thought 2 for one deal cool. But while I was driving the engine quit & found the 20 amp fuse blown it is fine with the key one only when you crank the engine to start the fuse blows what else could it be & yes the cooling fans keep running after the ECM fuse is blown? I need help I am unemployed & have to fix this myself I have no money.
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Old 06-02-2016, 11:39 PM   #2
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Since you replaced the ECM and the fuse still blows, I am thinking a shorted harness, like a possible rub through condition....that fuse only goes to the ECM, between the fuse block and the ECM, is where the short is....

Your best bet is to make a visual inspection of all wire harnesses in the engine compartment, looking for potential problems, like a harness rubbing on a sharp edge, or something like a stud penetrating a harness......
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Old 06-04-2016, 02:39 PM   #3
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I have looked over all the wires Can't find any shorts or rubbed through spots, Now I used the old E-prom from the old ECM when I replaced the ECM could their be a problem in it? Since I have no codes since I get the car to run because it blows the fuse when I start the car. Fuse in good in the on position but when you crank it is when the fuse blows.
Does anyone else have any ideas.
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Old 06-04-2016, 09:50 PM   #4
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While I went back out to continue trying to figure out my problem I saw the ECM fuse also says fuel on it & I pulled all the relays out putting the back in one by one until the fuse blow again I going to try a new fuel pump because the fuse blow when I put that relay back in.
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Old 06-04-2016, 10:28 PM   #5
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The fuel/ecm fuse feeds the fuel pump relay.....have you tried swapping relays first?

If it blows every time that you try to start the car, get under the car and look at the fuel pump harness.....is it cut anywhere, especially on the edge of the fuel tank? If you see nothing, disconnect the fuel pump harness and crank the vehicle....does the fuse still blow? If it doesn't, reconnect and try to start again...if the fuse does blow, you know it'* the circuit from the harness to the pump, or the pump itself....
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Old 06-05-2016, 11:39 AM   #6
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Yes I tried moving relays around in the every beginning when I had the a/c circuit code. The fuel pump harness run through the inside of the car & I already looked at it. to unplug it I need to drop the tank, there is not access panel to in in the car. Not sure how this would keep the fans running all the time but if I can at least get the car running again I can go to temp jobs & try to save up the money to get something better.
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Old 06-05-2016, 06:25 PM   #7
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I think when the fuse blows, since it also feeds the ECM, that causes the ECM to turn the fans on....

You have to drop the tank to unplug the harness? I wouldn't think so....
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Old 06-05-2016, 09:42 PM   #8
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The fuse does not blow with the fuel pump relay out which is what is leading me to the fuel pump. Once I can get the car running to drive it I can go back in later & see what codes are set nothing will set if it won't run.
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Old 06-06-2016, 11:28 AM   #9
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Do you want to drop the tank for nothing?

What if you drop the tank and put in a new pump and it still blows? Be kind of silly, right?

Disconnect the harness, at the fuel tank, and crank the engine....if it doesn't blow the fuse, now reconnect the harness, and crank the vehicle...if it now blows, you have verified the problem is in the tank circuit....
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Old 06-06-2016, 01:20 PM   #10
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Since I still have to drop the tank anyway to get to the connector for the fuel pump might as well put a new pump in & be done with it. no other way to get to the fuel pump but to drop the tank so no way to disconnect pump unless tank is dropped. With no access panel to get to fuel pump how else would I disconnect it. Pulling the fuel pump relay does the same thing it cut off power going to power to fuel pump so same as unplugging it that was how I always did it before & it would work for testing as long as the car runs & does not blow the fuse I can get to a temp job & try to save up to buy something better to drive that is the goal.
Oh & by the way the fans keep running even with the fuse blown not sure how that works but never the less I can put up with fans running all the time as long as the car runs to get me to a job where I can save up for something better to drive.

Last edited by hurricane; 06-06-2016 at 01:23 PM.
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