Okay guys, I need your expertise. I am pretty good with car electronics but I am having one HELL of a time getting this one figured out. Car is a 1998 Grand Cherokee and deck is a Pioneer DEH-P710BT (Premier).
So I installed a completely new audio system last weekend and everything is working great, except for the dreaded alternator whine. I started looking around the 'net to get some ideas of how to remedy this and I stumble upon the sleeping giant that is the "Pioneer Pico Fuse Problem". I had no idea. And suddenly, I'm crapping my pants because I seem to remember hot-swapping my RCA's.
Anyways, I pulled the deck last night and the first thing I did was tested for continuity between the RCA shield and the HU chassis. Much to my surprise, I had it. My resistance is 0.6 ohms. All of the sudden, I am stuck and I haven't even made it past step one. I decide to open up the head unit anyways to see if there is a bad fuse. Well, I got it open but I'll be ****ed if I can find any fuses. I can't find anything on the board labeled "FUxxx". In fact, all I found that I could even conceivably believe to be a fuse was something labeled "P401". I checked it for continuity and it was open. However, when I switched my DMM over to resistance mode, I got a resistance of 2.2 megaohms or thereabouts.
So at this point, I have no idea what I am doing and put the head unit back together. I put it back in the car and fired the system back up. No surprise - alternator whine is still there. So now I am thinking it is NOT the head unit. Even though I knew it wouldn't help, I tried the "ghetto pico fuse fix" and wrapped speaker wire around the RCA shields to chassis. Nothing. I start trying other things. I ran a 14-ga wire from the chassis to the amplifier grounding point (under the rear seat) and that didn't help.
While we are on the subject (and I don't know if this is pertinent to the discussion), let me mention something weird. So, I am running this ground wire from the black wire on the main harness of the deck back to the amp grounding point. When that doesn't work, I disconnected the wire, thinking that it would kill the HU. It did NOT. The head unit kept on running. I can't for the life of me figure out how. I mean, if the black wire in the harness isn't grounded, where is this thing getting its ground??? And I don't think there is any metal-on-metal contact. The mounting kit is plastic and completely insulates the deck from the dash. Like I said, dunno if it's related.
So, I am stuck. It doesn't APPEAR to be a Pico Fuse problem but I don't claim to be an expert. Alternatively, if someone knows the location of the Pico fuse on a 7100BT/710BT, I would be willing to check it again.
Some other info on my Jeep. I have done the "Big 3" and then some. First off, I took every factory cable (6-gauge) and supplemented (NOT replaced) that with an aftermarket 4-gauge cable. I have a dual-terminal Optima so I decided to make use of the side terminals, too. The positive is a 1/0-gauge cable running to my amps (two Infinity Kappa Five's). I then ran a 1/0-gauge cable from the neg side terminal and took that to a bolt on the frame, then ran a 1/0-gauge cable from that same bolt on the frame to an engine bolt. All in all, I am pretty sure the grounding is solid, but you guys tell me.
Also, there are RCA cables running down both sides of the Jeep so there is a set that parallels the 1/0-gauge power cable. However, the RCA cables are on the interior of the vehicle and the power cable is on the exterior of the vehicle (actually, it's running down the inside of the box frame rail). Think I could be picking up interference from that, even though there is the sheet metal of the floor pan separating them?
PLEASE HELP!
