Sound system issues- low AC Voltage ????

Aloha everyone,

I currently have the stock HU, replaced the fronts with Focal components, back door with Focal Coaxial, and put in a bypass (unplugged speakers and connected in a looped speaker adapter, this created 4Ohm load on rear channel) on the rear hatch speakers.

I’m currently in the middle of installing an AudioContol LC5i Pro, and JL Audio 900/5 amp. I’m using Metra T harness (“to amp”) with speedwire to the LC5i RCAs out to Amp, then Speedwire back to T harness(“from amp”). 4AWG for power and ground. Power for LC5i is tapped of Amp power (fused), and ground. The remote for amp is coming out of LC5i.

LC5i Pro was set up with instructions, amp sensitivity was set up initially at half. LC5i Pro powers up good, amp powers up good. First test went horrible, radio at 40 and barely a sound. I go to about 45 and the speakers clip, radio goes into “safe mode” disconnects from source and stops playing.

I check all connections and they seem good. I ran continuity test from T Harness (to amp) to LC5i speaker input and all test fine. I checked OHMs from speaker wire out of amp and all channels is registering 4 ohms.

I checked volts AC at LC5i speaker input and getting real low voltage:
Taking the following volts Ac readings at LC5i speaker input terminals:
Playing 1K sinnwave
.002 with nothing playing
.023 at volume 10
.071 at volume 20
.231 at volume 30
.70 at volume 40

These readings taken at RCAs (amp input). Same 1K:
0.0 at zero volume
0.002 at volume 10
.037 at volume 20, 30 and 40

I have a speaker wire to RCA coming in to bypass the LC5i and test the Amp with high level input.

I’m reaching out to see if anyone has had this type of issues.

Sorry for the long thread, but I’ve never seen anything like this.

mahalo,
Mac

 

No issues with my audio system.

I seldom turn it on.

 

I feel your pain chasing wiring gremlins. Which metra harness are you using? I couldn't find one on their website for 2023 model Year 4runners (I was going to check the wiring diagram). I suggest grabbing some voltages where you connected the speedwire closest to the HU. I'd start with front left (typically white wire +, white/black wire -) or front right (gray wire +, gray/black -).

If your readings are still low it may be a bad adapter. I used a PAC LPHTY02 harness in my wife's Toyota Highlander and the first one I received was bad.

And just to make sure, you have the nonJBL setup right?

 

I do not have JBL system. I’m also using the PAC LPHTY02.

I am only using the speaker side of that harness.
I am not using the power, ground or switched power from the radio so I plugged the large gray connectors back into each other.

Thanks for the heads up!! I did check voltage on the harness at the “to amp” and had similar voltage. I didn’t write them down but seemed low.

I talked to a Crutchfield rep and they are sending me a speaker to RCA adapter to test a connection from the HU to the amp high level input.

This is my first brand new vehicle, all the other vehicles were used…most already had the HU replaced so it was much easier just to connect via RCAs.

I’m stumped on what would make the voltage drop…or is it just the HU?