M27 fuse keeps blowing

Tonygunslinger · Nov 22, 2016

So this last friday, my jeep started up fine 3 times and the third time was a trip into town, about 10 miles. I parked, go into the store and about 50 minutes later the Jeep wouldn't start.

Turns out the ignition switch/window module fuse keeps blowing. It seems i can get one good start and drive and then i have to replace it again.

Maintenance/etc leading to this event:
- jeep sat for about 8-9 days
- the next day it ran 100% all around for errands
- then I installed 1 ton steering, a stabilizer and drag link short inner end.
- adjusted alignment and steering
- the next morning I installed the doors after a few months and washed it (it was on and off 3 times then)
- then test drove into town for steering n such
- then fuse M27 was blown.

And it keeps blowing, but I cant find any diagrams for all the wiring involved in this fuse/system or where i can troubleshoot grounds and such.

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cozdude · Nov 22, 2016

Tonygunslinger said:
So this last friday, my jeep started up fine 3 times and the third time was a trip into town, about 10 miles. I parked, go into the store and about 50 minutes later the Jeep wouldn't start.

Turns out the ignition switch/window module fuse keeps blowing. It seems i can get one good start and drive and then i have to replace it again.

Maintenance/etc leading to this event:
- jeep sat for about 8-9 days
- the next day it ran 100% all around for errands
- then I installed 1 ton steering, a stabilizer and drag link short inner end.
- adjusted alignment and steering
- the next morning I installed the doors after a few months and washed it (it was on and off 3 times then)
- then test drove into town for steering n such
- then fuse M27 was blown.

And it keeps blowing, but I cant find any diagrams for all the wiring involved in this fuse/system or where i can troubleshoot grounds and such.

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You have a short to ground somewhere, most likely in the door harness since you didn't have any issues until you installed the doors

Tonygunslinger · Nov 22, 2016

cozdude said:
You have a short to ground somewhere, most likely in the door harness since you didn't have any issues until you installed the doors

Do you know where I can find wiring diagrams online to assist in my wire digging???

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Frydaddy · Nov 22, 2016

M27

10 Amp Red

Ignition Switch (IGN SW), Window Module (WIN MOD)

I'm gonna guess something in the doors? Unplug them all, then plug in one at a time, checking for the blown fuse.

jeeeep · Nov 22, 2016

I would pull the door plugs and check them for corrosion/pulled or bent pin in the connector.

Pull one connecter, drive it around so you can narrow down which door is causing the issue...what was mentioned by others

Tonygunslinger · Nov 22, 2016

Frydaddy said:
I'm gonna guess something in the doors? Unplug them all, then plug in one at a time, checking for the blown fuse.

Unfortunately, I disconnected all of the doors and tried again, sadly the fuse blew instantly 2x and the jeep never got enough turn over to fire up. So I am thinking something other than the doors.

highoctane · Nov 22, 2016

Are your battery cables and the ground terminals next to the TIPM tight?

cozdude · Nov 22, 2016

Tonygunslinger said:
Do you know where I can find wiring diagrams online to assist in my wire digging???

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What year is your jeep? I can pull the diagram up at school today.

Frydaddy · Nov 22, 2016

Tonygunslinger said:
Unfortunately, I disconnected all of the doors and tried again, sadly the fuse blew instantly 2x and the jeep never got enough turn over to fire up. So I am thinking something other than the doors.

Then its something in the ignition switch wiring, That is the other system run b the fuse. Especially if it pops before the starter even engages. I would suspect the starter solenoid next.

Tonygunslinger · Nov 22, 2016

cozdude said:
What year is your jeep? I can pull the diagram up at school today.

It is a 2007 4 door

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Tonygunslinger · Nov 22, 2016

Frydaddy said:
Then its something in the ignition switch wiring, That is the other system run b the fuse. Especially if it pops before the starter even engages. I would suspect the starter solenoid next.

Ill slide on under and check it out! Any ways to properly test the pos and neg on components? Or do i just use ohms to look for an open loop?

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Tonygunslinger · Nov 22, 2016

highoctane said:
Are your battery cables and the ground terminals next to the TIPM tight?

Everything i played with up around there are yes.

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jeeeep · Nov 22, 2016

did you check for any wires that might be grounding behind the dash?
did you do any add-ons when the doors were off?

WJCO · Nov 22, 2016

Tonygunslinger said:
Ill slide on under and check it out! Any ways to properly test the pos and neg on components? Or do i just use ohms to look for an open loop?

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An open circuit won't be the cause. It has to be a short. And you won't be able to properly test it with a bad fuse in it. I really think it's going to be related to the door harnesses somehow. I would wiggle the shit out of those things and really inspect that they aren't rubbing on anything or pinched. The other thing you could do is put a good fuse in it and use one window motor at a time and move the window up and down like 10 times, try to get the motor hot and see if that causes the fuse to blow. Then try another window. If that doesn't cause the fuse to blow, I would check around your ignition switch area for any rubbing or pinched wires.

Tonygunslinger · Nov 22, 2016

jeeeep said:
did you check for any wires that might be grounding behind the dash?
did you do any add-ons when the doors were off?

I dont think i did any add ons with doors off. But it was about 3 months door less. The two light bars i wired up, the crappy tube fuse holder broke. So thats 2 sets of positive wires not fully transferring. But it dont look like the open wire can touch ground bc the plastic cap. Not sure if that could affect that particular fuse. Doors off last Thursday i did disconnect tie rod and drag link to swap in one ton tre and a moog inner drag link. Steering was off a little.

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Tonygunslinger · Nov 22, 2016

WJCO said:
An open circuit won't be the cause. It has to be a short. And you won't be able to properly test it with a bad fuse in it. I really think it's going to be related to the door harnesses somehow. I would wiggle the shit out of those things and really inspect that they aren't rubbing on anything or pinched. The other thing you could do is put a good fuse in it and use one window motor at a time and move the window up and down like 10 times, try to get the motor hot and see if that causes the fuse to blow. Then try another window. If that doesn't cause the fuse to blow, I would check around your ignition switch area for any rubbing or pinched wires.

Ill give it a shot! Think it may be a bad idea to push start it so i can get it home??

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pauljbrennan · Nov 23, 2016

Tonygunslinger said:
Ill give it a shot! Think it may be a bad idea to push start it so i can get it home??

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Have you tried a bigger fuse ? That often works.

RockyJk · Nov 23, 2016

pauljbrennan said:
Have you tried a bigger fuse ? That often works.

That's a good way to melt wires

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cozdude · Nov 23, 2016

pauljbrennan said:
Have you tried a bigger fuse ? That often works.

You should NEVER just replace a fuse with a bigger one. That's a great way to melt wires as rockyjk said and you can damage components in the circuit. Fuses are circuit protection devices

WJCO · Nov 23, 2016

pauljbrennan said:
Have you tried a bigger fuse ? That often works.

:grayno:

RockyJk said:
That's a good way to melt wires

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cozdude said:
You should NEVER just replace a fuse with a bigger one. That's a great way to melt wires as rockyjk said and you can damage components in the circuit. Fuses are circuit protection devices

Correct. Do NOT replace it with a bigger fuse. :hot:

M27 fuse keeps blowing

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