Wondering what the Red-Green wire goes to and a 2nd blk (pwr?) wire goes to - Included the diagram (from a 79 A/C manual) with my notes for the wires I can identify - I don't see where the A/C on/off switch is in the diagram but I'm not real experienced w/ wiring diagrams.

Mechanic says power to amp is good but no pwr out from amp. I tried TWO amps. Toyota says $450 for a new amp but I'd rather isolate the problem fully before throwing $ at it. A/C (R12 converted to R134a) works when compressor is jumped to battery but not via A/C switch. Thanks for any insights.

 

Well, according to the diagram you showed, and the pictures you provided (well done, btw, great pics, very helpful!), I think what you're calling red-green is actually referred to blue-red (L-R) in the diagram. I think the blue iis faded a bit, making it seem a tad green-ish. Anywho, it goes to a T, one leg to the blower motor, one to the Heater Relay. It's the main power input, also known as +VCC, coming from the battery, through the Heater relay, when it's energized, which is when the Ignition switch is on. Means that when the key is in the Run position, Not Start, the one position past Accessory, then the Heater Relay is energized, providing +12 VDC from the battery to the Amplifier.

One black wire (from the B terminal on the Amp, or #1) goes to the Ignition Coil. I'm not sure why, or what purpose it serves.
The other Black wire, from the L1 terminal (#8), goes to the Vacuum Switching Valve (VSV). That valve is, in the later models anyway, mounted on top of the engine's valve cover.

Does any of this help at all?
Pat☺

 

I don't see the A/C on/off switch in the diagram either.

Is this diagram from the factory Toyota manual? If so, is there a full vehicle wiring diagram in the back that may show more?

The wire going to the ignition coil is the Amplifier's RPM signal input. I believe that the Amplifier will cut off the A/C if the engine RPMs get too low to help prevent lugging the engine and stalling.

The A/C amplifier will only turn on the A/C when it gets all of the correct inputs from the A/C on/off switch, the A/C pressure switch, the thermistor, the, ignition coil, and of course the blower motor fan speed selector and proper power inputs.

I am a little confused about the wire colors too, but the colors can fade over the years and can "change color". It is also fairly common for Toyota to change the wiring colors too.

 

I could be wrong. I usually am, but I think the AC ON/OFF switch is on the amp circuit card, upper left corner of the actual card's picture.
In the schematic, it's not labeled, which it should be, but it's shown on the card, center right area, connected to terminals 5 & 6.

I do think, again I may well be wrong, that the blue on the wire is just faded out a little, making it LOOK green.
Of course, they may have run out of red-blue that day, and used red-green (appropriate! ) instead.

The older Toyota electrical systems were very poorly designed and implemented. Consider the starting setup. Terrible design.
Having said that, mine have lasted 30-some years now and still work fine. I need to replace the blower speed resistor in the pick up, but hey, if that's the biggest trouble I have with my vehicle electrics, I'll be very happy
OH! I did have to replace the Runner's Circuit Opening Relay. Again, though, for 30 year old vehicles, that aint bad at'all!

Good luck to y'all!
Pat☺

 

Hi All & thanks very much - Manual is a Factory Service Manual - (Will look for full wire diag) the knob on upper left of amp controls low/high settings for RPMs to kick the clutch on - Ignition Coil provides power to amp per comment above unless I'm mistaken - & looked again and that "Red" wire is definitely primary red w/ Green stripe (confirmed via disinterested party tho as indicated above may or may not match wire diag.

Questions: How can I check whether I have a functioning Amp? & What/where is the Circuit Opening Relay referenced above?

Thanks again for providing these insights!

 

The Circuit Opening Relay shuts the fuel pump off if the engine stops running. Like if you get in an accident, the engine stops, but you do NOT want the fuel pump to keep running just because the key is still on. Good chance for fuel all over the place, so a very dangerous fire hazard. The COR stops the fuel pump, ensuring the fuel leakage is minimal. Good safety feature, IMO. It's turned on by the AFM flapper opening, IE: you're getting air in through it. Engine stops, no air flow, no COR, no fuel pump.
The COR can be bypassed by shorting the Fp and B+ terminals in the test setup, that hangs off the fuse box in the engine compartment. If you're having fuel problems, you can check to see if the fuel pump is actually functional. If it is, you've now eliminated that as a possibility. You can also check the fuel pump's volume and pressure without having to start the engine, thus eliminating the pressure regulator, fuel lines, fuel filter, etc etc. as the problem. Very handy trouble shooting tool.

The COR is located behind the right kick panel, just above the ECM (the computer). Easiest to get to if you just unbolt the ECM, and leave the cables connected, and just kinda move it out of the way, then the COR, which, IIRC is held in by one bolt on the top of it, is pretty easy to get to. Cost me about $60.00 or so at the dealership.
Was hilarious when my wife called to ask if they had it. Parts man didn't have a clue what the heck this thing was, and worse, it was a WOMAN describing it. What it looked like, what it was used for, where in the truck it was located, and so on. Poor guy didn't have a clue. Had to go find an experienced mechanic to talk to my wife. It was even worse when she called them to order the crush washers for the cold start injector...
Oh well, 30 year old truck. I honestly think my trucks are older than the parts guy at the dealership!

Anywho, there ya go
Pat☺

 

Wait, I thought we were talking about a 1979 ish truck, so there isn't a Circuit Opening Relay, or Air Flow Meter, or diagnostic connector(s), or Engine computer.....

 

Thanks for clarifying 2ToyGuy - funny tale

Correct old87 it's a 79...RN47004195

Here's A/C manual & Another Wire Diag (there are 1) USA Version I enclosed above, 2) AU Model diagram and 3) General Country I've now enclosed here. I assume USA is the one I will refer to as it's a USA truck.

 

I apologize. I happened to mention the COR in passing as the one major electrical component on MY 4Runner that has failed in the 30-some years I've owned it. He asked what and where it was, and I have a terrible habit of getting a bit overly verbose at times,
I apologize for going off at a tangent that way.

Thanks very much for the explanation of what the wire to the coil is for. Now I know, as they say

Lastly, I don't see any AC On/Off switch, if it's not the one on the amp. At least not marked as ON/OFF or something similar. Maybe a different schematic? I don't see it on the second schematic, either, unless it's the one labeled Control Switch? Just to right of amp on the schematic?

Sorry again
Pat☺

 

Hi 2ToyGuy, nop apology required; I learned alot from your above - I think you're correct re A/C Switch - in "USA Trucks" it's called "Control Resistor" in "General County" it's referred to as "Control Switch" per your above. Seeking to discover if I can determine which Amp "pin" number goes to which physical location on the Amp itself sice I read above the wire colors may or may not match the diagramThanks a lot.

 

Hi
According to the schematic, you want the Yellow-Black and Yellow Green wires, which are clearly seen in your picture, up in your first post. The third picture. According to the schematic, again, they're labeled as pins 7 and 9. I get confused trying to count the pins in the plug it's self. You would think there would be a pin between 7 and 9, like you know, pin 8 maybe, but in the picture they're right next to one another. Who knows. The early Toyota electrical systems weren't the best designed IMO. But hey, I was only a Radar tech my entire working life, whadda I know?

Does this help at all?
Pat☺

 

 

Heck, they're nearly 40 years old! I wasn't very good at 40, and I just keep getting worse as I age. Electronics are similar, believe me. I worked on radar systems in the 80's that were designed and built in the early 60's. Talk about failures...woofta!
Electronics don't age all THAT well. I would be surprized to find 1 out of 7 to 10 units still good. But ya never know...

I wish you good luck, though!
Pat☺