Mechanics

IS THERE A SHORT CIRCUIT SOMEWHERE

1999 GMC Jimmy • 130,000 miles

Ecm 1 fuse keeps blowing as soon as ignition switch is turned to on and p0339 code 99 gmc jimmy
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Fabriciogaleana
September 28, 2012.



The fuse blowing indicates a shorting somewhere and you would need to diagnose what is causing it by understanding the fuse circuit first.
P0339 is a fault with the CKP (crank) sensor. Check its wiring and ensure it is not affected by the exhaust manifold or anything else that could have damaged it.

Where does the code 99 comes from?


KHLow2008
Sep 28, 2012.
Sorry I meant that my car is a 99 gmc jimmy and the only code is p0339. It has to be a short circuit that comes and goes for sure and blows ecm 1 fuse as soon as the igniton key is powered up yesterday 2 things happenned while me and my father in law tried fixing it. One time I installed a crank sensor and ignition control module I got from a local auto dismantler and the truck fired right up of course at this time for whatever reason the ecm 1 fuse was not being burned up it was fine and ran great for about 30 sec all of a sudden very loud noise resembling an electrical short fuse was heard and truck dies and not starting again with a code that said the ignition module was bad, changed the module to the original one and then had no codes on the pcm but the ecm 1 fuse was being burned up again, after wiggling the wiring harness around we somehow got the fuse to stop blowing and started getting the crank sensor code listed above.A list of the components that could cause the fuse to keep blowing would be very helpful as it seems I cant find that info anywhere online or my repair manual also if you guys know any known common areas these vehicles develop short circuits that info would be great too we just had a baby 6 weeks ago and going to a mechanic shop right now is not financially possible please help!


Tiny
Fabriciogaleana
Sep 28, 2012.
Ok well hope someone replies soon. After digging around a found a big purple wire that is part of the harness and ends somewhere around the starter I found it hanging loose does anyone know where this wire should be plugged into


Tiny
Fabriciogaleana
Sep 28, 2012.
Pink or purple?

It should be a power feed from the ECM 1 fuse and the diagram shows what are linked to it. Tape it up first and after starting engine, check for trouble codes.


KHLow2008
Sep 29, 2012.
Really appreciatte the help but I actually gave wrong information the fuse that keeps blowing is the eng 1 fuse NOT the ecm1 fuse weird thing is that on the socket where that fuse goes im gettig 12 volts when both terminals are tested on a voltmeter but my fuse doesnt blow and just hours ago it was burning through fuses like crazy but now they are not blowing but still getting 12 volts from the fuse terminal witout using an outside ground just both terminals of the fuse socket what does this mean


Tiny
Fabriciogaleana
Sep 30, 2012.
I installed a test light on the eng1 fuse slot and it lit up I disconnected all of the sensors on this circuit and when I disconnected the last one which is the MAF sensor the light went off I then started plugging all of the other seonsors back in and the light never came back on until I plugged the maf sensor back in and when I disconnected it the light went of again I tested the electrical connector that feeds power to the maf and both tests my repair manual says to do indicate that the connector is good and receiving proper power and proper signal from the pcm. Does this mean the maf sensor is causing the short circuit killing my fuse?


Tiny
Fabriciogaleana
Oct 1, 2012.
So it seems I still have a short but I cant trace it im reading a 12volt signal when I probe both eng1 fuse terminals which would indicate a short circut but the fuse is not blowing this doest make sense to me since the fuse should blow since its getting a positive and negative charge


Tiny
Fabriciogaleana
Oct 1, 2012.
If one side of the fuse has battery voltage, the other should have too unless the fuse is blown.

You are confusing me with your testings.


KHLow2008
Oct 1, 2012.