Factory Radio No Power - Amp question

I've read through a lot of the posts about this, but they either end up with and easy fix that hasn't worked for me, or no resolution.

Just purchased a 2000 Limited AC 2wd. Everything works inside and out including dome lights. Have checked every fuse under the dash and in the engine compartment with multimeter and test light as well as visually.

the hvac connectors are plugged in and all functions there work. This seems to be the easy fix, but no dice.

The factory radio with 6 disc player does not have power to either the blue/yellow constant hot nor grey accessory hot. It only has the one connector coming up from the small factory amp.

I can't quite reach the factory amp with my hand, but can see a blue/yellow wire and a grey wire. I'm assuming these correspond with the power ones at the back of the radio?

Can I check for power there if I can get to them? What's the best way to get to that amp without tearing apart the lower dash?

 

You need to test for power at the amp itself. Two connectors attach to the factory amp. One carrying power and one pair of speakers IIRC, the other carrying speaker? I'd need to look at the EWD to be sure. But certainly two connectors.

I suspect one of your plugs isn't plugged into the amp fully, has a bent pin, or the amp is fried. You'll know the latter is true if there is expected voltage on one of those plugs. If not, your problem is elsewhere. If you need the EWD for your truck it's linked in the 4th or 5th paragraph of this thread.

(These two connectors are also where all the $10-20 adapter harnesses you should be using for aftermarket radios will plug in. Only assholes cut factory wiring!)

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I have power to two wires on the large plug and reduced voltage to one on the small plug.

Best guess is amp is fried since no power goes from it to the radio plug.

 

It's entirely possible, power signal comes into the amp on the lower plugs there, then up to the head unit.

You say it's low voltage, it's entirely possible something inside the amp requires more power to be able to push power up? Or it may be blown.

Here's the wiring diagram thread that's linked from inside the top couple paragraphs of the megathread, which will help in your case --> https://www.tundras.com/threads/ultimate-tundra-wiring-diagrams-collection.81448/

For full disclosure, I hate reading wiring diagrams available for these vehicles, they make shit sense to me. I've modified the page for yours a bit to more clearly show the relationship of power feeding into the amp, and the single line to the radio.

If I'm reading thie right, The colored wires showing under the amp go out to speakers. That should leave three other wires for power and ground: Thw two showing on top of the amp (grey, blue w/yellow stripe) and the ground out of the bottom far-right (brown).

I would confirm based on my shitty understanding of this:

• 15A fuse for ACC is not blown
• 15A fuse for Dome is not blown
• On the plugs to the amp, test the blue/yellow wire for 12v, and test the grey wire 12v (since I can't tell which, if not both, should have power based on this)

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thanks for that. I’ll need to dig deeper. Got a better meter to confirm.

Brown ground is good at both amp and radio plugs.

Grey wire has 12 volts at amp plug.

No other wires have power at the amp plugs.

All fuses still good check with ohms unplugged and voltage both sides with power on.

 

If you're not seeing 12v at the blue/yellow wire with the key in the ON position, I'd be skeptical, and would be checking both sides of the 'DOME' fuse plug in the in-dash fusebox to confirm it has power on one leg. I'm assuming it does if the overhead dome light works.

I also don't know what/where junction/connector "J7" is showing. I assume one of those feeds is coming from the engine bay fusebox. I'd need to dig more - no time right now. Have you checked your fuses in the engine bay? Legend for them is under the lid.

 

Yes, some light works.

Have checked every fuse under the hood and dash both sides for power. I even turned on lights, AC, etc. to confirm every fuse.

I’ll swap the two 15 amp fuses for the radio just to triple confirm.

Really appreciate the help. Going over the other threads with more info on the wiring diagrams.

 

The Blue / yellow wire is constant power and that does not have power in my harness. #4 in the image.

I swapped fuses with brand new ones and everything else works.

Started tearing out interior panels and found an Enforcer SLI 840 alarm spliced into the harness. I only have regular keys for the truck, so that’s a new find. Assume my issues are related. Haven’t found any other fuses yet.

 

Aftermarket alarms are a huge burden for these trucks.

That said, you may also want to check your interior fuse box for water entry. It’s only one circuit you have impacted but the fact it’s not doing anything seems worth a check. for evidence; see pics & pics & pics, it happens a LOT. Normally causes more circuit probs than just one though.

 

Alright, back at this. I discovered the modular behind the hvac was burnt up and assumed that was the cause of my no power issue. I swapped in a replacement and same issue. No power to the blue / yellow wire for constant 12v. The grey wire does have switched 12v to it. The dome light works and the fuses are good. I did not see water issues in the interior fuse block.

Anyone know where the J7 junction connector is in this image? It's between the integration panel and the dome light. I just don't know if that's behind the dash somewhere or above the headliner. My guess is there's a splice or wire disconnected due to the aftermarket alarm using the dome light power as well. It's the only thing I haven't traced where there should be constant power to the radio.

 

Appears to be somewhat beside Instrument Panel ?
If that drawing is from 2000 EWD, there is a section labeled Electrical Wiring Routing....Position of Parts showing locations of connectors if you need more.