Fuse 21 (ASD/FP) Keeps blowing. Please help.

Icon_xof · Post by **Icon_xof** » Fri Mar 11, 2011 6:07 am

What would cause fuse #21 (ASD Relay) in the PCM of my 04 Dodge Neon SXT to keep blowing? No OBDII codes, and no alarms from my ultragauge before it happens. Just blows while I'm driving (in any weather condition) and the car's dead until I put in a new fuse. The stock fuse is a 20amp, and it's blowing 30amp fuses. Don't want to risk trying a bigger fuse. This first happened about 2 months ago. Replaced the fuse and it started right up. Did a tune up asap and found plug #2 was pretty loose so I figured that may have been the cause. Ran perfect for a while. Now, all of a sudden starting Monday night, I can't go more than a few miles without the fuse blowing. Just went through 5 on what's usually a 30min drive.

I haven't done any mods on it, at all. I bought it used from a buy-here-pay-here place. They told me up front it was a salvage and showed me pics from before. The previous owner rear ended a truck. I got it anyway because it ran great and I got an amazing deal on it. It still runs great until that fuse blows. The only other issues I'm aware of are 1)The 6-cd changer doesn't work. The lights just flash. and 2)The switch for the fog lights doesn't set enough for them to turn off. If I press on it, even very lightly, they'll shut off, but only while I'm holding it.

I set up my UltraGauge so I could monitor the voltage going to o2-1 and o2-2 (which I assume are the high and low o2 sensors). I noticed that the voltage going to o2-2 stay pretty consistint, anywhere from .650v-.780v from what I've observed, but whatever it's at it usually stays at that value for a few minutes at a time. o2-1, however, is very erratic, ranging from .005v to .800v and will bounce anywhere in that range in a second, and does so constantly. Every second the ultragauge updates and every time o2-1 is a very different number than it was the previous second. Is it normal for the top o2 sensor to have such a varying voltage? And if that's indicative of a bad sensor, shouldn't my check engine light come on or at least throw a code? (btw, while the fuse is blown my OBDII port doesn't work)

One last thing: During my lunch break, I started my car and let it idle in park for 20mins and it never blew the fuse, which is much longer than it will last while I'm driving. When I'm driving it will blow at intervals anywhere from 10mins to as quick 1min. So it appears to only happen when I'm driving.

Any ideas? Thanks in advance.

Post by **occasional demons** » Fri Mar 11, 2011 8:44 am

The fuse is in your PDC Power Distribution Center.

21 powers a multitude of things.

The fuel injectors, ign. coil, ASD relay, fuel pump relay, PCM, Data Link connector. possibly a few more. It is going to basically be a matter of searching for a chafed wire, or bad components. Sorry there is no good direct solution for this one.

Icon_xof · Post by **Icon_xof** » Sat Mar 12, 2011 11:10 pm

I found it. According to the diagrams in my Haynes manual, the only things directly wired to the ASD besides the fuse are the PCM and the Alternator. The ASD interacts with everything else via the PCM. So I started at the Alternator and traced the wires up to the PCM and I found where the short was. The loom with the alternator wire in it had been pinched against the front of the tranny when the previous owner wrecked it. The shop that fixed it must have missed it. So I opened the loom, then spliced, soldered, and taped the damaged wires, and now it's all good =] Thanks anyway.