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Shannon Martin
Shannon Martin, ASE Certified Master Technician
Category: Chevy
Satisfied Customers: 589
Experience:  over 20 years as a line technician both asian and domestic.
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Chevrolet K5 Blazer 4x4 (Full Size) 87 blazer new motor ecm

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87 blazer new motor ecm b fuse blows when hooking up battery brown wire bundled with o2 sensor broken with no end on it what does it go to

Shannon Martin :

hi i am shannon i will help on this issue.

do you have a test light?

do you have a volt meter ? i can get you a diagram . and help with testing . just let me know if you want my help. just post back.

Customer: replied 6 years ago.
have both but cant get power to wire because when i hook up battery fuse blows all i can test is for breaks in wiring chilton and hanes diagrams dont help

i have seen this before new engine installed and the ECM B fuse blowing. most likely the wire for the oil pressure switch has got pinched at the bell housing between the engine and transmission. the ECM B fuse powers the fuel pump.







if this info answered your question then please press the ACCEPT button .thats how i get paid.i will still answer on this issue just ask fallow on question. thanks shannon

Customer: replied 6 years ago.
so oil pressure switch is on rear of motor toward driver side if thats true i am tryin to figue out how it could get pinched if i pulled motor and tranny together wires were laying on the cowl wires around trans have no signs of being pinched the origional wiring for fuel pump hasnt worked for years I rewired that with a toggle switch on the dash if the brown or orange wire is my problem where is the other end of it does it need to tie into the fuel pump if so where is the origional wire from the factory for that

if you look at the last diagram i sent you will see the ECM B fuse powers the fuel pump and the ECM .i don,t know what changes have been done to the wiring system . but if you are not using the fuel pump relay or oil pressure switch . i would start their.





Shannon Martin and 3 other Chevy Specialists are ready to help you
Customer: replied 6 years ago.
still stumped looked at all wiring and replaced oil switch and fuel pump relay still blows fuse have any other ideas does the relay switch get a signal from the fuel pump itself to see if its there or not
ok look at the relay on the side is a diagram. look at the bottom the pins are numbered pin 30 is the power form the F pump fuse. pin 87 is the gray wire to the fuel pump . if you jump pin 30 to 87. the fuel pump should run .if the fuse blows then their is a short in the gray wire.pins 85 & 86 are the magnetic coil that activates the relay one pin get power from the computer .it only has power for three seconds. the other is the ground .try jumping 30 to 87 see what happens.let me know
Customer: replied 6 years ago.
ended up being the computer shorted out replaced it and the truck fired right uo thanks for all the help
no problem you can use me any time i am tech sgm11155