Mustang keeps blowing fuse

[fast02max]

Alright so I have had my car for a couple of months now and haven't had any problems with it really so far. Well last night I took the car to Gateway Raceway to make some passes and on my 3rd pass I was in 4th gear and the car started sputtering then shut off. I had no clue what was going on so me and a buddy pushed it back down into the parking lot and got ahold of someone with a trailer. I noticed that my fuel pump wasn't kicking on so I figured maybe I had tripped the inertia switch but that was still fine. Well as we were setting there I noticed a 20A fuse that was blown under the dash so I swapped it out and voila the pump kicked on and the car fired right up. Well I tried driving it home and about 15 minutes later I see a blue flash under the dash and then the car stalls out again so I pull off the side of the highway. I swapped it out with a 30A this time hoping maybe that would get me homw but as soon as I turned the key forward it blew as well. So I put it on the trailer and took it home. So then earlier today I was looking under the hood and I had found an old amp power wire that came straight off the battery that had come unplugged and was just laying under the hood so I plugged it back in thinking this was the solution to my problem, went and got some more fuses and put the new one back in and as soon as I turned the key it blew out. I'm assuming that I have a short somewhere but I was wondering if maybe anyone else has had this problem and it be an actual component like the CCRM or the ignition that was bad. Any help would be appreciated. Thanks.

The fuse I am talking about it is the number 18 in this diagram the top left which is a 20A fuse that's for the Instrument Cluster, Transmission Control Switch Module, the Constant Control Relay Module, and the ignition system.

 

[Steven]

Well I would suspect a CCRM long before a ignition switch. They either just go dead, or start malfunctioning. Definitely a possibility it shorted out one of the inner relays. Just go to LKQ and get you one off of a taurus or something and try it out. Fixed my problem (on my old car)

 

[fast02max]

Well I just went out and unplugged the CCRM to take it out of the equation and as soon as I turned the key forward the fuse blew out. I've been looking everywhere for a shorted wire or something and I can't find anything. Guess it's time to break out the volt meter and spend a whole day testing wires :BangHead:

 

[AaRoN]

Voltage drops, voltage drops, voltage drops.

 

[fast02max]

Yessir :thumbsup:


Fun fun fun!!!! :violent1:

 

[CC'S95GT]

try to disconnect the fuel pump from the circuit then see if the fuel blows.
Also ck into the distributor. It controls the fuel pmp after the key is turned to start.

 

[fast02max]

try to disconnect the fuel pump from the circuit then see if the fuel blows.
Also ck into the distributor. It controls the fuel pmp after the key is turned to start.

Alright man I'll check into it

 

[AaRoN]

You need to get your hands on a wiring diagram. Definitely sounds like a short to ground somewhere. I'm assuming that maybe it has/had something to do with that amp wiring setup.

 

[fast02max]

You need to get your hands on a wiring diagram. Definitely sounds like a short to ground somewhere. I'm assuming that maybe it has/had something to do with that amp wiring setup.

Yea that's what I'm kind of figuring to...I'm afraid it fried a module whenever it was unplugged bouncing off of the frame rail. But I'm really leaning towards a short to ground somewhere before the electrical load since it's blowing the fuse as soon as any sort of power is supplied to that circuit. I can't find a diagram anywhere, I found one for a 5.0 Foxbody but they don't even have the CCRM and so that really does me no good lol.

 

[AaRoN]

Yeah, the short to ground has to be before the load in order to blow the fuse.

 

[fast02max]

Well I didn't use a DVOM today because mine is at school and my dad was out of town so I couldn't get his. So I spent a good portion of the day looking through the wiring thouroughly and I can't seem to find anything, I came across several things I thought could be the problem but when I fixed them I turned the key forward and the fuse still blew. I unplugged the fuel pump, then the ccrm again, then the ignition control module, then the alternator (I read another thread where supposedly he had the same problem and that was the solution) but the fuse still blew everytime. I pulled apart my dash to look behind the radio and the gauge cluster and found some wires that were left in there for like a tach and just some loose wires and fixed them up but still at the end of the day with a fuse plugged in as soon as you turn the key forward it blows. I'm bringing my DVOM home tomorrow and I'm gonna do a lot of voltage drop and continuity checks between the wire and a ground but hopefully I figure something out soon. I hate electrical problems.

 

[ttocs]

your fuel pump could be caught on something and just drawing too much current when it turns on rather then a short.

Try disconnecing it and then powering the car up.

 

[AaRoN]

Mechanical resistance will increase current draw but you generally only see something like that in the starter circuit.

 

[ttocs]

if the pump has locked up for one reason or another, it could cause this problem. It is easy enough to test and at least try to narrow down where your current draw is. I agree that there is a current draw that is popping fuses somehow but I have seen no proof of a short yet.

 

[AaRoN]

Who knows. He's found a few different wires hanging around that were open. Maybe there's one more that he hasn't found.

 

[fast02max]

Well I did already undo the fuel pump but it still blew the fuse when I flipped the key forward...but I don't think the fuel pump is the problem because it's not blowing the fuel pump fuse it's blowing the fuse that controls the ccrm, igntion, instrument cluster, and trans control switch module. So I'm assuming the pump isn't kicking on as a result of the CCRM circuit being open.

 

[CC'S95GT]

does it still blow when the ccrm is disconnected?

 

[fast02max]

does it still blow when the ccrm is disconnected?

Yep sure does. I unplugged the CCRM and it blew. Then I unplugged the fuel pump and it blew. Then I unplugged the instrument cluster and it still blew and if I unplugged the igntion well I don't think anything would happen because it wouldn't be telling everything to power on so I'll have to test that with my DVOM soon.

 

[fast02max]

Alright guys I finally figured out the problem. So today I brought my DVOM home from school so I started messing with some voltage and continuity tests. Well the first thing I did was put the ground clamp on the negative battery terminal and check the hot wires for continuity, well nothing was popping up. Finally I decided to try that on the hot wire going to the coil, well when I did my DVOM beeped so I knew something was wrong. I unplugged the coil flipped on the ignition and the fuse didn't blow. Well at first I thought the coil might have internally shorted out but upon resistance testing it I knew the coil itself was good. So I traced the wires from the coil and still found nothing. Well finally I noticed a small cylinder that is grounded underneath the coil which I read is a ballast resistor to help keep the humming out of your radio or something like that. Well there was a hot wire that was pinched in between that and the bracket and sure enough when I pulled the wire out it was sparking and the insulation was burnt and bare wires were sticking out. So I plugged the coil back in after I pulled that wire out and started the car!!! I fixed the wire so it wouldn't happen again, the most frustrating thing of all is that I saw a guy post another thread having the exact same problem blowing the same fuse and this is what was causing his problem as well, I didn't understand what they were talking about though at the time, but I do now lol.

Thanks for all the input and trying to help me out with the problem though guys I really do appreciate it ccasion14: I'm just glad this nightmare is over because for me electrical problems are the most frustrating thing that can happen on a car.

 

[CC'S95GT]

glad you got it.
tough find.