Old head stolen, installed a new head, now no sound - what th'?!?!?

[Pete]

Ok here's what happened. So my head unit was stolen. It was a Sony FM CD 25Wx4 blah blah blah. I got another head unit, similar to the old one only with more power, installed it, spliced it all in good and proper, power it up and - there is no sound. Nothing. No hum, no pop, no nuthin. This truck is a '91 XLT with the factory JBL premium system with the factory sub.

So I took the head unit back out of the dash and started looking around to try and narrow down the problem. I noticed that the connector for the speaker wires was mangled from when the dog turds stole the stereo (they destroyed the dash by the way). Well, I had not noticed that before. So I cut off the connector and stripped the wire ends. I then took a known good sound source (a boombox) and hooked it to each of the bare speaker wire pairs that used to hook to the factory connector I cut off. Again, no sound, no nuthin. I have the Ford EVTM wiring diagram so I know which wire pair goes to what speaker.

To eliminate the head unit being bad, I took a known good little extra speaker I had and connected it to the terminals on the back of the head unit and the little speaker worked fine in each case. So that eliminated the head unit - the problem is in the car. The new head unit works perfectly.

So I then took my meter and checked for continuity across all the speaker wires. There is no continuity anywhere, none at all. I also set the meter on resistance check to see if the applied low DC voltage would make the speakers pop - nope. So, this tells me there is a break someplace in the system downstream of the head unit.

Is there a fuse or CB in the power amp or the sub amp? Where else should I look? Maybe when they stole it, it shorted and tripped a CB or fuse to the power amp? I have not checked continuity of the wires from the dash end to the amp end - that is the next step. All the fuses in the main vehicle fuse panel are good.

What I can't figure out is, since they stole the head unit only, how could that have possibly affected any part of the system that was downstream of the head unit? Since there is no continuity across any of the speaker wires that tells me there is an open circuit affecting all 4 speakers and the only thing in common to all 4 speakers is the power amp. Think my power amp was damaged due to the theft? How could that have happened? And how do I check it out?

Any help or insight or ideas you can provide would be VERY much appreciated. Thanks guys.

 

[Kustom Toyz]

Well Pete, I am sorry to hear about your mishap. I have had the same experience about two yrs ago with my 92 xpolrer EB. I also had the problem as you are. I need to know if both connectors were damage or if it was just the speaker connector. I will go ahead and give you my insight. I frist installed the new head unit and hd the same problem. I did everything you did with th boom box and speaker. About two weeks of fooling with it (Yes two weeks) I looked at the colors or wires on the HU and they were different then the wires going to the speakers. I forgot all about the factory amp in the back. So after takeing it to my home stereo shop to try to find out whats what, they finally say was that there is no amp. I prove them wrong. Took the back panle off and showed them. So I try and try to figure it out. About a week I followed all wires to the amp anf to the speakers. The only ting i found was that the BLUE wire at the HU harness needs to be connected to the ant. wire. That will trun the amp in the rear on. Sorry about the long drawn out letter. I just wanted to let everyone know how much f a pain in the ass it is for someone to jack your ****. Sorry again pete, if any other Q's just e-mail and I will try to help as much as possible. You can take a look at my homepage. Hope this helps.

 

[Pete]

Kustom Toyz thanks very much for your reply. I will try your idea tonight. WHat about the other blue wire? Is that the actual amp-turn on wire?

Thanks again for your help!

 

[Kustom Toyz]

Ok pete here we go. I had to go out to my truck because I didnt want to guess to much more. Here is a run down as my head unit is hooked up.
SPEAKERS
Fords Factory Harness What wire it is

- Blue Front Right Possitive
- Purple/white Front Right Neagitive
- Green Front Left Possitive
- White/orange Front Left Neagitive
- White/Red Rear Right Possitive
- Brown Rear Right Neagitive
- Blue/Black Rear Left Possitive
- Yellow Rear Left Neagitive
- Sheild Ground

POWER
Fords Factory What they are New Harness
Harness To New H.U.

-Green/yellow Memory Yellow
- Black Vechicle Ground N/A
- Yellow/black Possivite 12 volts Red
- Blue/red N/A
- Orange/black N/A
- Black/green Radio Ground Black
- Blue Mute

This is what is going on. With the power wires, Green/yellow goes to your memory, Yellow/black goes to 12volt+, Black/green goes to ground with sheild and radio, and the last and most improtant part is Blue and yellow/black splice these together with your red wire comin from Your new head unit. This Blue wire (mute) acts like your remote trun on/off to the factory amp. I hope this help, and let me know how things work out for you.

 

[Pete]

Well I looked it over and sure enough I had not hooked up the blue wire. The wire is even marked "Amp Remote"! Duh! So I hooked it up and it works perfectly.

Thanks for taking the trouble to go out to your truck and look that up for me - I appeciate it! Pete

 

[Pete]

Oh yeah - Are you sure about these:

- White/Red Rear Right Possitive
- Brown Rear Right Neagitive
- Blue/Black Rear Left Possitive
- Yellow Rear Left Neagitive

I think you might have the polarity backwards on these two speakers. I think the solid wire is positive but I'm not sure. The Ford wiring diagram is not marked, at least mine isn't. Where did you get this info?

 

[Kustom Toyz]

I am glad it worked for you pete. I got those right out of the back of my headunit. You can hear a differents if you hook it up backwards. This is the way mine is wired, and it sound BEAUTIFUL. Any other questions I am here. You can even e-mail me. Take it easy and have fun listening to soun great sound!

 

[Bill O'Rights]

Almost 9 years old, yet this is the thread that solved my problem. Exact same problem. Everything seemed to be working fine, but no sound at all. Damn blue wire. Phhtttt!

 

[SHARK X]

great advice. just what I needed gracias