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1991 Gmc K1500 Blows Ecm Fuse


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#1 dbrianson

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Posted 01 January 2010 - 05:38 PM

I have a 1991 Gmc sierra k1500 that constantly blows the ecm fuse sometimes as soon as i turn on the key, i pulled the fuel pump relay and its still blows. I changed the ecm module and it still blows, unhooked the oil pressure switch and it still blows. If i let it sit for awhile and plug in a new fuse it will crank and run for a long time, but if i start down the road it blows the fuse and dies, sometimes quickly and sometimes i can drive a few miles. i have looked over obvious wire and dont see anything but im about to set this thing on fire.

#2 Nytemare

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Posted 01 January 2010 - 06:16 PM

I would grab a wiring diagram and see where that wire ties in with everything. Sounds like you have a short in the crank position...look for a wire that goes to that fuse and in turn to the ECM that's hot only in the crank position.
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so you expected something that weights 5000 pounds and has aerodynamics of a piano to get what?


2003 Silverado XCSB, 4.8L, Flowmaster super44 SI/DO, G80 3.42, MSD Wires, K&N drop-in filter, Yellow Top Battery, Royal Purple in entire Drivetrain, W4M tune....My DD..............................SOLD
2010 Silverado XCSB 5.3L Z71 Summit White, Diablo Trinity tuned....more to come soon.
2010 Cobalt 2.2L LT 2Dr. Victory Red....gas saver/wife's Car.......SOLD
2011 Cruze 1.4L Turbo 1LT Crystal Red ...Again, Wifes car and gas saver
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#3 dbrianson

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Posted 01 January 2010 - 07:28 PM

I would grab a wiring diagram and see where that wire ties in with everything. Sounds like you have a short in the crank position...look for a wire that goes to that fuse and in turn to the ECM that's hot only in the crank position.


thanks, ill try to trace that out.

#4 dbrianson

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Posted 01 January 2010 - 07:48 PM

where can i find a wiring diagram? i've looked everywhere.

#5 dbrianson

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Posted 01 January 2010 - 07:59 PM

i forgot to add that the guy who had the truck before me said the ecm fuse started blowing after he changed the starter.

#6 Nytemare

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Posted 01 January 2010 - 09:33 PM

Check the starter enable wire for fraying...I believe its still purple on your truck. Its Obviously on the "crank" side of the circuit. Buy a Haynes manual and they will have the diagrams in the back.

Also check that its the right starter and solenoid for this truck. I have seen people remove the solenoid from an older or newer model starter and Frankenstein a starter together to make it work. I would be looking all around that general area.
Posted Image

so you expected something that weights 5000 pounds and has aerodynamics of a piano to get what?


2003 Silverado XCSB, 4.8L, Flowmaster super44 SI/DO, G80 3.42, MSD Wires, K&N drop-in filter, Yellow Top Battery, Royal Purple in entire Drivetrain, W4M tune....My DD..............................SOLD
2010 Silverado XCSB 5.3L Z71 Summit White, Diablo Trinity tuned....more to come soon.
2010 Cobalt 2.2L LT 2Dr. Victory Red....gas saver/wife's Car.......SOLD
2011 Cruze 1.4L Turbo 1LT Crystal Red ...Again, Wifes car and gas saver
1978 LJ80, 16V 1600cc on 31's, Spring over lift, awaiting Full Frame off build...The Toy

#7 dbrianson

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Posted 02 January 2010 - 09:55 AM

Check the starter enable wire for fraying...I believe its still purple on your truck. Its Obviously on the "crank" side of the circuit. Buy a Haynes manual and they will have the diagrams in the back.

Also check that its the right starter and solenoid for this truck. I have seen people remove the solenoid from an older or newer model starter and Frankenstein a starter together to make it work. I would be looking all around that general area.


Thanks, ill do that.




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