Weird wiring problem

[Jeepskate 10+ year member]

Okay, this one has got me stumped. I had my system setup with a single 5-channel amp...fused 4 gauge from battery to distro block, 8 gauge to cap and amp & 8 gauge ground. Due to the vehicle being a Jeep (top & doors are off right now) and poor front speaker placement (have a full roll cage which prevents me from mounting the speakers in a better spot), I bridged the 4 'normal' channels to 2 for the rear and added a second higher wattage amp for the front (8 gauge power to the distro block & 8 gauge ground (same ground spot as the other amp). Here's where it starts to get weird: bring the system up to test & tweak and the 5 channel amp starts smoking on the input side (I suspect I had something set incorrectly for the inputs vs. bridging...I have a support call in to MTX since the manual was pretty thin on this info). As I'm laying the amp back in place to go back up front to shut everything down, I hear a click like a fuse popping or circuit breaker tripping and the amp's power light goes out, but the other amp's light stays on (it's a slightly newer MTX and the light on it seems to also come on when there is a wiring fault). I disconnect everything except the power, ground & remote from the 5-channel amp, power back up, and neither amp nor my EQQ (also in back under the back seat) powers up and I notice that my cap isn't showing voltage anymore. Check the fuse at the battery & it's okay, stick a meter on the cables at the cap and get weird readings, so I take the cap out of the loop. Still no go. Meter both power feeds from the distro block with my ground and get about 11.8 volts. Try a known good old Alphsonik amp and it doesn't power up either...take it up to the battery and it powers on, so I then start checking my way down the power feed...check the cable from the battery to the fuse, okay, check the protected side of the fuse, okay, check the connector at the protected side of the fuse, okay, remove the cable from the distro block, nothing, but still reads 11.8 volts. I then made some quick & dirty 'pigtails' for the MTX amps and tried them out and got the same results. There are no breaks in the 4 gauge cable and it passes through a grommeted hole in the firewall. I've never heard of it or seen it before, but is it possible for a cable to build up resistance and in effect 'go bad'? I have some old cables from a system from years gone by that I'll do some more testing with, but this one has definitely got me scratching my head.

Click to read more...

 

[Jeepskate 10+ year member]

Looks like it was a bad ground. Last night I ran a temporary ground cable to the spot where my head unit & signal processors are grounded and it worked. Weird...everything worked fine for 2 months.

 

[Jeepskate 10+ year member]

Up & running again this weekend. I ran the 8 gauge grounds to a distro block and the remnant of one that I shortened was re-used from the block to one of the body mounting bolts (the chassis grounds to the frame through these bolts and there's a ground strap on the passenger side engine mount to complete the circuit to the alternator). First time in almost 20 years (dang, I'm gettin' old) off-and-on of dabbling in this hobby that I've had a ground problem. Cleared up all of the weird problems I was having...was starting to think I had lost my touch and should just act my age and yank out the sub and hook the speakers up to the head unit ;-) Planning to do the big three this week, just waiting for my 1/0 to arrive. I'll post some pics if you guys are interested once I pretty everything up. The Jeep is a complete rebuild from the ground up that I've been working on off and on for a little over a year...finally drove it again a few weeks ago. Nice to have the money to indulge some of my fantasies from my younger days.

After purchase in 1999:

Later in the year after a little lift and some minor mods back from the trails:

Nearing completion of the rebuild (been too busy tweaking & driving to take new pics):

Install in progress (head unit is in the console):

Powered up for the first time:

 

[sumone 10+ year member]

looks good...glad it all worked out.

 

[Jeepskate 10+ year member]

Big 3 is done and I think all of my noise is gone now. Couldn't do a full check since I had a jackstand holding my drivetrain up while I replaced the ***** filter & gasket. Started the engine and the upper radiator hose was riding on the alternator (oops). Just got one head unit issue to work out...get audio from the tuner, but not from the CD with it installed (worked fine initially). Popped it out last night, hooked up a speaker, set it next to the battery and powered it up and everything worked fine. Going to re-wire everything in the center console tomorrow since it stopped working after I fiddled with that wiring.

 

[Jeepskate 10+ year member]

Back in action...'old school' caught up with me. The last head unit I'd installed had a single wire for power antenna & amp turn on, this one has separate wires. I had used the turn-on for the signal processors and the antenna for the amps...you can probably guess what happened. Switch to CD, power antenna lead powered down turning my amps off. At least it forced me to clean up my wiring...

 

[Jeepskate 10+ year member]

Wow! I got everything buttoned up yesterday and ran the Jeep for a while with the system on whil I added & checked the ***** fluid...what a difference. Absolutely no noise, and thanks to the big 3 I'm getting a solid 13.5 volts instead of 12.8