Troubleshoot Stereo Issues

2001 tan 4runner -lifted- After a bad jump I replaced about 5 fuses including the alternator. I'm not incredibly savvy with repairs but I manage to do most on my own. Everything is working again except there is currently no power to the antenna or the stereo (which I had replaced in 2012 and has been working well ever since). The (ACC) fuse under the steering wheel blew but i replaced it so theoretically it should be getting power. Are there some things I should do to address the problem? Thank you in advance for any advice

 

There is usually a fuse on the back of the stereo itself. May have blown that one too.

 

Looking at the wiring diagram for 2002 (should be close to the same)...if I read it right:

The 15A ACC fuse in the fuse block in the interior feeds the main power to the radio. (Grey Wire at the radio, 12v with key on)

The 15A Dome Fuse in the engine bay fuse block feeds power to the radio also. (Blue/Yellow Stripe at the radio, Constant 12v)

Did you verify no power at the stereo? (Grey wire) If there is power at the stereo, maybe it's a fuse like 4scooter19 says. Otherwise, the radio may be blown.

The antenna looks like it runs off the ACC line for power (Grey Wire) but is activated by the radio.

Obligatory: get\download a copy of the FSM (factory service manual) for your year!

 

The Blue/Yellow wire would be the "keep alive" power for the radio. Basically, it holds the radios memory active, so when you turn the truck off, you don't loose the stored stations, and whatever else there may be.
The Radio should work, if the main power line, the grey wire, has the +12VDC on it at the radio when the key is in ACC, or ON, with or without the keep alive voltage.

IE: Loosing the keep alive is bothersome, but not critical. Loosing the main power line IS critical. Quite often, as was mentioned, there's an in-line fuse in the main power line, somewhere along it's length. No fuse in the keep alive line, other than whatever fuse it's tapped off of in the truck's circuitry.

Check the voltage on the main power line, from where it's picked off from the truck's circuitry, all the way to the radio. Often the cabling has a plug right at the back of the radio you can pull off to check the main power line. If there's a number of plugs/connections along the main power line, it's easiest to break the circuit in half, IOW: go to a plug or connector about 1/2 way through the line, check the voltage, with the key in ACC.
If it's good there, go 1/2 way further along the line, measure the voltage, etc, until the voltage is no longer present. You know the between the point at which it's bad, and where it's good, is the problem.
If it's no good at the 1/2 way point, go towards the source of the main power line, again 1/2 way at a time, until it's good. Problem is in the section between the good and bad points.

Good luck, and keep us up to date on how things are going...
Pat☺

 

Hello,
I have a 2000 4runner and swapped out a stock stereo HU with another stock unit from Sept. 2001 looks identical, when I plugged it in with the 3 factory connectors and antenae, the 15A acc fuse blew immediately. I then unplugged the HU and replaced fuse and all was fine. So now I'm thinking did Toyota change the Batt and GND wires on the Head unit side or is it a bad stereo I purchased with an internal short. On my 2000 HU I measured resistance across the GND terminal and 12V batt, and GND and IGN pins. both had high resistance no short. I will do the same on the 2001 HU and see if has a short across either of these two power and GND pins. I have all 3 FSM for this truck and could not find any of them covering the wiring, is there a 4th book. I read another guy had the exact same problem as I am having and he did not finish thru to tell anyone what he found, I hope I did not buy that guys head unit. lol...

 

Hi, mtbwally.

First thing to check is to plug the "old", or original unit that was in there. If the fuse blows again, the trouble is in the wiring, or something else in the circuit that fuse feeds. You said that when you unplugged the new unit, the fuse didn't blow again. Can I presume that means that everything that had been on in the circuit that the ACC fuse feeds, was still on when you replaced the fuse, removed the new unit, and tried again?
If the fuse did NOT fail with the original unit plugged in, I would definitely say the new unit had a problem. I doubt Toyota changed the Hot and Ground wires. If the new unit blows the ACC fuse, and the original unit doesn't, it's the new unit, not a wiring change.

Good luck! Let us know how things work out for you.
Pat☺

 

Thanks for the replay PhantomTweak, The reason I had purchased a new HU was the volume knob on this vehicle never worked when we bought it. I have an electrical background and was trying to find a replacement volume switch and replace just that part. I found the newer HU easier and was 50.00 bucks, was in good looking condition, I tried it and found the fuse blew, but I had so many parts of the car torn apart in the engine bay since we just purchased it a month ago from a neighbor. It had engine issues and they had the dealer do a compression test on no. 3 cyl. had 60 psi, I confirmed that before buying it, misfire codes as well. wasn't sure if it was a stuck injector and washed the cylinder down with excess fuel or rings were stuck. Head gasket was my first guess but no coolant in oil at all, now it was stuck rings or cracked head. It was the latter. 136k miles and my guess from yellow burnt oil in the head oil was not changed that often. Had the head welded up two cracks in the no. 3 cyl. one from intake valve to exhaust and the other exhaust to spark plug. both were micro cracks. Been busy at work and tired of wrenching so its taking me a bit longer than when I was younger. lol. heads back on and exhaust is on just need to put the intake and the rest back together. The engine grounds were not connected and I was concerned if those gnds were part of the radio gnds, but I will put those two head gnds back on, as the engine is the main gnd point. 12v Battery I believe is connected to the block as Most if not all electrical items still work in the interior. So this truck received way more love than I was expecting to give it right out of the gate. Fuel injectors, coils and plugs, fuel filter, water pump, idler pulleys etc. This was suppose to be a quick DD for my daughter after her car was totalled by someone running a red light.
I swapped out the volume knob today and will be trying it out in the vehicle on wed. The previous owner or dealer removed or shoved in the rear window key socket that adjusts the window up or down. possible motor damage and they just removed it in the up position. not sure why someone would do that or was that a safety thing from breaking into the rear hatch. not sure. they disabled it that's for sure. its the base model no frills but will hopefully run for a long while without major issues.
I have had two Toyotas previous to this one way back, 1996 22R-TE 2wd, which after several blown Turbos went with a Garrett BB with adj. waste gate, nothing crazy but no smoke burning threw the bushings of the Toyota Turbos. Then I had a 1992 4X4 with the 3.0 6 cyl. what a slow POS sold that and went full size trucks after that.
I do like how simple these trucks are, 3 or 4 bolts sizes and you can fix anything. Pretty cool. Anyway I'm newbie on this forum and I thought I'd share some fun under the hood with you guys. The head was fully rebuilt one exhaust valve was slightly burnt, they replaced all valve seals replaced the one valve seat and cleaned up all the other valves as well as the welding and changing the one valve shim. it was pretty reasonable $450.00. Its called Precision Cylinder Heads in Lake Forest if anyone needs help with their cracked heads.

 

Status of blown fuse from Stock Head unit on base model 4runner MY 2000 there are 3 seperate connectors on the back of the stereo HU two White connectors that are side by side and a Grey connector on the other side of the unit. It took me 5 fuses to figure it out. The Grey connector when plugged into the HU blows the fuse once ign is applied. I figured the 6 way connector was all speaker wires, the connector next to that had speaker wires and power, so I left those two plugged in and removed the greay connector that fit the slot but was not the same 12 way connector so I thought that was odd. Put a new fuse in and turned ign to on, pressed the power button and radio turned on, turned the new volume knob from other HU, and it worked, radio all works now, All the accessory center dash works now, except the clock might need a new one it is not working. actually had the rear glass window go down and up but made a crunch sound when put all the way back up, I will need to open up that rear license plate frame and see whats in there maybe the key cylinder is floating in there and just needs a new clip of some sorts to hold it back in its place. All I can think of is the Grey connector must be for a amp or something, kinda odd the HU has the header connector for a amp or preamp but the base model only gets the std amplification of the HU.
All is good now, time to get back to the engine assembly again.

 

Just so you know, the rear window mechanical "stuff", and the key switch, are accessed from the plate on the inside of the tailgate, not the license plate frame area. Essentially, the area below the glass. A few screws around the carpeted plate, then a few more on a metal plate under that, and everything to do with the operation of the rear window, including the keyswitch, is right out in the open. You have to put the glass all the way down, and open the tailgate to access everything. It's actually very easy to get to.

As for grounds, there are several that matter greatly. Heck, the ALL matter greatly. People don't pay attention to grounds the way they should, really. There are two main ones directly on the negative lead of the battery. One to the engine's block, generally connected to the adapter for the AC compressor.
The other, directly to the body metal, usually connected just in front of the battery, right behind the headlight. That's the one that provides the electrical equipment inside the cab, heck, nearly everything other than the starter, it's ground. The starter gets it's ground from the first ground I mentioned.
There should be a ground from the head to the body metal, from one of the bolts on the rear lifting hook to the firewall behind the head, right about where the halfmoon seal in the valve cover, is located. That one is critical to the proper operation of the engine, as it's where the spark plugs, injectors, and so forth, get their ground.
The alternator gets it's ground from being connected to the PS pump adaptor.
Needless to say, you're free to add grounds, whether directly to the battery, or the body metal, etc, as you deem necessary.

As for grounds inside the cab, there is one on each side, behind the kick panels. One on the left, or driver's side, is a bolt into the body metal, with 4 wires crimped into the o-ring. Be aware, the crimps loosen over time, so it's important to check them regularly. The other is on the passenger's side, near the ECU, with a wire directly to the ECU providing it's main ground.

It's critical to keep all the grounds, both ends, clean and free of dirt, corrosion, and so on.

Does that help any? BTW, I'm glad you got the other problem fixed.
Pat☺