Amp Troubleshooting Needed (PICS)

[HighRollerRich]

I also posted this on GMFS. I copied it here for more OBS owners to help.

I've had this amp, sub, & headunit for 5 years.

Just did a big overhaul of the front end suspension and swapped in a manual transfer case. The Tahoe has been sitting for 4 months with no engine battery connected. The battery is brand new.

I get it back and the amp will not turn on (no power light on amp).

I have the worst skills when it comes to electricity and wiring. A friend wired it back in the day. I want the sub only to get the amp power. the door and rear speakers are working and not amped.

1999 OBS 2 Door Tahoe 4x4 LT

AMP
-Kicker 750.1
-Bolted to top of box in back of Tahoe.

SUB
- Kicker 15" solo baric? its square.

Box
-custom ported box. Width: back of OBS 2 door Tahoe. Length: about 1 ft. Height: sits level with back of foldable passenger back seat.

Headunit:


Things I looked at:

Looked at inline fuse on the power cable and it is okay. It sits near the airbox in the engine bay.

I started with the power cable to the Tahoe engine battery. I lightly pulled the power cable from the terminal and it came apart. So I bent the terminal open and placed the wire in and crimped it to the terminal again. Didn't fix the problem. Here is a picture of terminal after I fixed it.

Pic 1

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So I looked at the connections at the amp. Here they are.

Pic2

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Pic3

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The "ON - OFF" selector on the side for the "Sub-Sonic" was in the OFF position when I got the Tahoe back.

Pic4

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Here is "something" on the ground cable coming from the amp. The cable runs from the Ground amp power cable to a hole in the passenger rear wheel-well. It's a hole in the side of the upholstery of the interior and the sub box covers it from sight.

Pic5

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Then I found this in the POWER CABLE coming from the battery to power the AMP. its pictured above as connected to the other large GROUND cable on amp. It seems to be crunched from the passenger side back seat(row) mount.

Pic6

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same spot, rotated over 180 degree
Pic7

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I pulled the headset just to be sure they're connected. Here is what the back of the headset looks like.

Pic8

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Pic9

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Pic10

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Questions:

Are audio cables in PIC 3 and 4 "Audio Input" connected to the right spot. The cables run to the back of headunit at "Audio Out Rear" in pic 10?

Could that crimped power cable in Pic 6&7 be the problem? Causing amp not to turn on? What would you estimate the gauge of this wire to be?

there is a small blue and white wire spliced into back of headunit wires Pic9 to a connection BETWEEN the amp power and ground cables in pic2 labled "REM". What is it? Is that correct?

How could I test to see if amp is broken?

Is there anything obvious that is out of place that you see?

 

[df2x4]

The REM wire is a remote turn on lead for the amp, it's what actually tells your amp to turn on. That is where your problem lies I'm guessing. That power wire crimp really should be addressed at some point before it wears through the jacket completely, but I seriously doubt it's the cause of your problem. If you have a multimeter then you can test for +12v on the remote wire to determine if you're transferring the signal properly. Alternatively, you could just temporarily connect your amp's remote terminal to a known good +12v source. If you do that and the amp turns on, then you can start diagnosing the problem with your wiring. If not, the amp itself may have died OR someone may have blown the tiny internal pico fuse inside your head unit that fuses the REM lead. I've seen that happen before and it was a nightmare trying to diagnose. That wire is only designed to deliver a tiny amount of current, and if you daisy chain two or three amps to it with no relay to support the extra draw then you can blow that fuse and render your REM lead completely inoperable. That's not a fuse you can replace yourself either unless you're very skilled with a soldering iron. I'm sure you probably thought of this, but did you check the fuses ON your amp? Those two 40A red ones in pic 2. If those are blown you definitely won't get any power. To answer your other question, your RCA connectors carrying the audio signal to your amp are indeed connected properly. Also in regards to the gauge of your power wire, I'd estimate 4ga but if you read the print on the jacket it will most likely say somewhere.

EDIT - One more side thought about that battery terminal you fixed. Those larger gauge cylindrical ends are near impossible to get crimped using traditional methods. Just looking at it, you might want to buy one of these or find someone who has one you can borrow and re-do that if it seems loose at all.

http://www.ebay.com/itm/Hammer-on-Terminal-Lug-Crimper-Weld-Cable-Crimps-Wire-Car-Stereo-Amp-Audio-/191079761726

I bought one of those a few years ago and I haven't had to use it much, but when I do need it I'm really glad I have it. Just set your terminal and wire in there, lightly hold it in place and whack the top of the thing with a hammer.

 

[HighRollerRich]

Thanks df2x4 for the response.

The 2 fuses on the amp are the original ones and are not blown.

as for the multimeter on the power cable. You're saying check for +12V before and after the crimp to see if there is enough voltage, correct?

You say i could check the REM wire to a 12 volt source. you're saying disconnect REM wire from amp and test voltage, correct?

I remember seeing the head unit fuse on the backside of the head unit, although I didn't check if it was good or not. It sits under main colorful wire connector in PIC9.
I don't think I have daisy chained two or three amps to the connector, I only have one amp.

I'm going to assume the amp is good because it was working when I turned it off. It's more likely the mechanics folded the backseat down on the power wire and crimped it rather than the coincidence of no amp working all of the sudden.

 

[kamokevin]

Like df2x4 mentioned, I would check those two fuses on the amp itself. Then I would replace the crimped power wire (probably not the problem, but could potentially start an electrical fire under the right conditions). The REM wire should go from the radio's harness to the REM terminal on the amp, which it looks like it does. Make sure it's not crimped or anything. Check the ground for the amp and make sure it makes good clean metal contact.

Use a multimeter to verify that you're getting power to the amp when the radio is on. If not, REM wire might need to be checked again. However, the stereo could also be to blame. Go into the stereo's audio settings and make sure the sub is set to "on" (if that's an option). Also it looks like you have a bass remote knob, make sure that isn't set to 0.

 

[df2x4]

Thanks df2x4 for the response.

The 2 fuses on the amp are the original ones and are not blown.

as for the multimeter on the power cable. You're saying check for +12V before and after the crimp to see if there is enough voltage, correct?

You say i could check the REM wire to a 12 volt source. you're saying disconnect REM wire from amp and test voltage, correct?

I remember seeing the head unit fuse on the backside of the head unit, although I didn't check if it was good or not. It sits under main colorful wire connector in PIC9.
I don't think I have daisy chained two or three amps to the connector, I only have one amp.

I'm going to assume the amp is good because it was working when I turned it off. It's more likely the mechanics folded the backseat down on the power wire and crimped it rather than the coincidence of no amp working all of the sudden.

Like I said that crimped power wire probably isn't your issue. I've seen much worse than that with the system still running. I was referring to the remote wire as far as the voltage testing and checking with another 12v source. Your amp needs to see 12 volts from that wire, otherwise it won't turn on. The fuse in the head unit I'm talking about is actually internal and is not user serviceable. The one instance where I ran into that being blown the solution ended up being just buying a new head unit because the price of repair was astronomical. And you're welcome, I love messing with this stuff.

 

[HighRollerRich]

kamokevin

Thanks for the reply. The bass knob is connected and turned beyond 0. As for the head unit, I was thinking the same thing. I can press the main button and cycle through fade, left, right, rear, front, bass, mid, treb, and SUB. SUB has always controlled the sub/amp kinda like the amp bass knob. Is that what you mean by checking the sub on it?

Also, the face plate rotates forwards and downwards to allow a cd to be placed inside of it. When i got the Tahoe back the face plate was disconnected from the stereo. I have never done that before. I fitted it back and it seemed to display properly but could there be a problem with the connection there? The leads that connect the face plate to the rear do not look damaged.

 

[HighRollerRich]

Like I said that crimped power wire probably isn't your issue. I've seen much worse than that with the system still running. I was referring to the remote wire as far as the voltage testing and checking with another source. Your amp needs to see 12 volts from that wire, otherwise it won't turn on. The fuse in the head unit I'm talking about is actually internal and is not user serviceable. The one instance where I ran into that being blown the solution ended up being just buying a new head unit because the price of repair was astronomical. And you're welcome, I love messing with this stuff.

So you are saying test the remote wire (aka REM wire), which is connected to the amp between the power and ground cables, where it connects to the amp? the REM wire runs from the amp to a splice in the ball of wires on the backside of the head unit in PIC9

 

[df2x4]

Yes indeed. I would disconnect that wire at the amp and test it to see if it gets power when your head unit turns on.

 

[HighRollerRich]

okay thanks. I will have updates tomorrow. I now have a reason to buy a volt meter

 

[kamokevin]

kamokevin

Thanks for the reply. The bass knob is connected and turned beyond 0. As for the head unit, I was thinking the same thing. I can press the main button and cycle through fade, left, right, rear, front, bass, mid, treb, and SUB. SUB has always controlled the sub/amp kinda like the amp bass knob. Is that what you mean by checking the sub on it?

Also, the face plate rotates forwards and downwards to allow a cd to be placed inside of it. When i got the Tahoe back the face plate was disconnected from the stereo. I have never done that before. I fitted it back and it seemed to display properly but could there be a problem with the connection there? The leads that connect the face plate to the rear do not look damaged.

The faceplate thing shouldn't be a problem. The brain of the stereo is in the body rather than the faceplate, it might even play music even with it disconnected, so I wouldn't worry about that.

Check all menus and sub-menus for all bass settings and make sure they are turned up or on. If you are using auxiliary, go to the auxiliary settings menu and check there. Do the same thing if using USB/bluetooth/radio etc. When I put in new rear speakers a month ago, they would work for radio, but not bluetooth purely because the rear speakers were turned "off" in some deep bluetooth sub-menu.