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88 Chevy Burb blowing ECM-B fuse

cabledawg

cabledawg

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As the title states, lately I've been blowing the ECM-B fuse about every other run. I'll check the load with a multimeter when I get home but does anyone have any clue why this would happen? Seems to run fine otherwise and just started this about a week ago.

88 Chevy R10 Burb
350TBI/Ranger OD/365 trans
Originally had a 700R4

No recent work has been done and I haven't checked the ECM via WinALDL.
 
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Had the same problem with a 4.3 S-10 Blazer, turned out to be the ECM. Replaced with a used unit and all has been well for 5 plus years.
 
Might want to check the grounds for the ECM,some GM's used a "bus bar" under the kick panels to ground several important wires,that often get all gangrene from moisture and create a high resistance..
 
Well she's dead for good now. Fuse isn't blowing anymore but the same problem exists. I'll be grabbing another ECM this weekend to see if that fixes the issue and I'll check the grounds prior to the swap.

Thanks for the info guys.
 
I would put the correct fuse back in with the new ecm. I have seen bad lock up wiring/solenoid cause this fuse to blow intermittently.
 
I'm trying to remember, if I am correctly, I had a ECM-B fuse blow out on me one day. I went out to start it in the morning, wouldn't start, checked all fuses, fuse was bad, replaced it, then wasn't getting any spark if I remember right.

I checked the fuse again and all were still fine. I ended up having to replace the pick-up coil inside the distributor.

TWICE.

I bought the cheaper one the first time, it burnt out in a few days, bought the name brand and was running that one till the other wiring issue that parked it a few years ago until recently found and fixed.
 
cabledawg said:
As the title states, lately I've been blowing the ECM-B fuse about every other run. I'll check the load with a multimeter when I get home but does anyone have any clue why this would happen? Seems to run fine otherwise and just started this about a week ago.

88 Chevy R10 Burb
350TBI/Ranger OD/365 trans
Originally had a 700R4

No recent work has been done and I haven't checked the ECM via WinALDL.
Click to expand...


Replace the oil pressure sender they like to short out internally and blow the ECM-B fuse randomly.

This fuse powers up the fuel pump so it's possible the pump could be bad blowing fuses until it gives for good.

I don't think the ECM could cause this fuse to blow without some dramatic smoke.
 
try looking into your fuel pump going bad. When a fuel pump goes bad, it can (sometimes) internaly ground out, and pop your ECM-B fuse.
 
I've seen quite a few GM vehicles that had a bad fuel pump power wire,in the harness ,somewhere between the firewall and fuel pump...the wire gets internally corroded and green,and acts as a resistor,and can cause the fuse to blow,or the lowered voltage to make the fuel pump not want to work or overheat,and cause the same thing...a lot of mechanics just toss a new fuel pump in and figure that "fixed" it after the fuse doesn't pop for awhile,or it runs good again...temporarily..then they end up fixing the real cause--the wiring..
 
Look at the 4 injector wires that run in a "notch" into the throttle body. The air cleaner housing will rub these wires and cause a short. Mine did this and was blowing ECM A and B.
 
Well whatever the problem is now is beyond a fuel pump I think. Switched power works but nothing else does. No headlights, dome lights, horn, or anything else that should work regardless of key position. And I already checked fuses and wiring to the ignition block on the steering column. But the radio and HVAC come on with the ignition. Seems the wiring gremlins have beat me again :angry1::angry1::angry1:
 
check the wiring harness where it runs along the side (outside) of the frame under the driver seat. this is a spot, which has a d tenecy to rub through, and screw up evey thing.
 
I've worked on a few that the wires have rubbed through behind the engine block as well. Top side, behind the distributor. Just remembered that..
 
I'll check the wiring in both those locations. The ECM I thought I had available isn't the right one but there is a place in town that has some for cheap. But I'm ready to give up so if you guys know anybody that wants a project truck I might let it go cheap. :frown1:
 
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