aftermarket radio NO SOUND help

B

BlackIceLSC

Registered
1993 Lincoln Mark VIII
factory JBL
3 years ago I installed a Pioneer DEH-line single-din head unit it Tommy's 93. I used a Metra wiring harness adapter, and it installed perfectly and operated totally normal.

Recently, the sound became so faint, you literally had to crank the volume up to 50 just to hear the sound.

I suspected the factory JBL amp had died, and purchased a used one from a known-good source.

it arrived and I plugged it in, and Viola, the sound was back to normal, except there was some crackling in the R/F door speaker at times.

I suspected the used(un-tested, as was fairly disclosed to me) amp might have internal problems. I opened the amp up and sure enough, a couple of the diodes had burnt connections.

Not having another amp, I purchased a "factory amp by-pass harness" from Metra. it basically plugs in to the INPUT harness at the amp and the OUTPUT harness, literally by-passing the amp all together.

result: NO SOUND
none at all. not even a mild pop, or static when tuned to a dead radio frequency. CD controls, all controls on the HU work normally, just ZERO sound. Yes, I checked to make sure the settings weren't set to "mute" or anything related to user error.
I double-checked all connections, and they are correct.
I then checked the car's fuses. I found the 20-amp Maxi-fuse for the JBL under the hood was blown and replaced that. I also checked Fuse #16 and #17 listed simply as "radio".
all fuses are good.

As I stated, this HU worked just fine before swapping the amp.
The rest of this lengthy post provides more details in hopes of answering questions, so only read on if you need more info to help. Thank you.
__________________________________________________________________

replacement amp MUST BE 93-94 only. I have 95 amps, but they have different plugs. I have no more correct amps in stock to test further.

when we took the replacement amp apart, we tried to solder the broken diode connections, but solder grounded against the amp frame and permanently damaged the amp(smoke DID come out, which is probably what blew the 20-amp Maxi fuse)

the Metra amp by-pass harness has the same (8)colored wires as the speaker harness(green, green/black, gray, gray/black, purple, purple/black, white, white/black). But one end has 10-wires coming off, which I assume are CD changer wires(pink and light blue)

I removed the original(previously working) Scosche wiring harness adapters and connected the Metra harness as a form of trouble-shooting, but that did not fix the problem.

I completely removed the after-market harness and plugged in a factory HU and still had no sound.

The 10 amp mini-fuse at the back of the Pioneer HU is not blown(checked).

Some online research indicates perhaps a grounded speaker thus changing the impedance(2 ohm vs 4 ohm?) and Pioneers will kill the signal by default if this happens.

I replaced one speaker just to check if somehow magically all speakers were blown during the attempted amp repair and resulting "smoke by solder" debacle.


any suggestions would be appreciated as we have gone from a HU that had sound, albeit faint, due to dead amp, to full sound with crackling speaker with used/replacement amp, to NO SOUND with amp by-pass harness.

Thank you.
 
Craig, I'm assuming you retried plugging in the amp again (faint sound one) to verify that the HU still works? I'm thinking that the no sound has to do with the HU knowing that there is no amp load on the amp turn on lead or "pre-out" and therefore isn't allowing the HU amp (basic 45 watts X 4) to power the speakers. Just like if you were previously using RCAs to an amp for sound the actual speaker wires on the HU would not be used. I bet if you disconnect the amp turn on (blue/white or just blue)(also called antenna lead for power antennas) wire from the harness you may get sound.
 
old faint amp hit the dumpster from 40 yards(3 pointer) a few weeks ago.

as for your blue wire trick, I did that. the antenna went down, but there was no sound.

I totally get where you're going with this. It just amazes me that Metra, supposed to be one of the top end harness manuf. would sell a amp by-pass harness if there was more to do than just plug and play.

I have tried all the 'tricks'...I even went so far as to literally take an aftermarket amp, power it up, hook an aftermarket speaker to it, and plug it in via RCA's to the back of the HU and turn on the SW mode.
not even a peep from that set up, OUTSIDE the car.(looked like I was dyno-tuning the stereo set up!)
 
Ok...I think you probably already know the answer but we will humor this a lil more.

So, just to understand your steps and the order.

First, replace amp and toss other amp (sswwwiiish).

Second, replacement amp has better sound but dying channel.

Third, remove replacement amp, soulder connections and re-install?

Fourth, turn on key and smoke show?

Fifth, attempt to bypass amp with harness?

Sixth, find blown fuses?

Seventh, try another head unit?

Eight, disconnect amp lead?

Ninth, dyno tune radio with Pioneer HU still installed?

Tenth, did you try another HU?
 
I only tried a factory HU during this trouble-shooting process.
just one
it worked in the parts car I yanked it from.

you have all other steps correct.

I suspect 1 of 3 things:
1)the harness I bought(amp by-pass) doesnt work in this scenario
2)there is a problem elsewhere related to my plugging in the failed-re soldered amp(short)
3)there is a bad speaker connection somewhere in the car that is causing the Pioneer to kill the sound/channel(read that somewhere on a help forum)

when I tried the factory HU as a means of troubleshooting, I realize that with NO amp at all, it probably wouldn't work anyway because I don't think you can retain a factory HU and use a by-pass harness and have it work at all. Jamie mentioned there is a amp by-pass module on the back of a stock HU where the factory harness plugs in, so perhaps I should remove that and try again.

I just need to hear something out of these speakers so I know there is not an internal wiring issue in the car's main harness. In other words, if I can get sound to play out of the speakers via ANY method, I'd know were were good there, and then isolate if it's the amp harness or the Pioneer HU itself.

grrr.

thanks for trying on this one.
 
I think it's number 3 but it's because of number 1. :) Seriously, the Pioneer HU won't play sound if it's not detecting good connections (via the bad bypass). And if it's not that...I think it's because you eff'd up and did number 2. Which is ultimitaly the answer I think you alread knew, lol. You don't have another HU (aftermarket) you can plug/play to test it out?
 
turns out...the POS amp bypass is WRONG.
They do NOT work.

here's why:
for the 93-94 JBL amps, the phone plug-looking connection is the INPUT.
the two outer connections are the OUTPUT.

the Metra harness does NOT work in a 93-94 JBL amp by-pass set up because all it does is connect the two speaker harnesses together.

it's like taking a garden hose and cutting it, and then looping to end you cut off and expecting water to come out of it!

that's why no matter what I did, there was never going to be any sound because I was going FROM the HU to the "phone jack" looking wire in the trunk, and NEVER sending a signal from that BACK TO the speakers.

so my new options are:
1)keep trying to find a known-good working 93-94(only) JBL amp.
2)directly wire the speakers to the HU.

the easiest way to go would be to get another amp.
the best way to go would be to spend the time running wires to the speakers, which is not something I'd like to be doing since he wont care either way.

his car
his money
my time.

thanks for helping on this one J....I appreciate the efforts.
My bad for trying to find the problem when the problem was not knowing the bypass harness doesn't work on 93-94
 
I installed a 4 channel aftermarket AMP in my Mark VIII. I just wired the stock wire to the amp. It works but the tweeter are now on one channel.


Next project for the Mark VIII is to re-run all new wire to the speaker and new front speaker. Rear speaker are new.
 
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