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OK, I looked up a pic of your particular switch and I can see what may be confusing a couple of us. It looks like the letters A/C would probably light with the dash lights but what I'm asking is, is the little light to the left of the letters lighting up with the dash lights even when the ac is off or is it just the letters lighting up? I'm sure it's just a miscommunication but if the light indicating that the AC has been turned on is lighting up with the dash lights even when it has not been turned on, then we have an actual symptom that can narrow the search down. If we're just talking about the backlight on the switch that comes on and goes off with the dash lights, then I just misunderstood you.
I'll have a look over the illumination schematic tomorrow if I get a chance. Send me a message in case I forget or don't get around to it by say dinner time.
But I'm pretty sure there are not a back light just the indicator light that turns on with the AC switch.
Here is that backlight. It is power on pin3 ground at pin1 of the A14 plug.
And the switch, with its indicator. Is pin 5 shorted to pin 4 (failed LED indicator lamp)?
The upper dot represent pin1, below is pin3, X is the indexing key(filled hole). Could there have been contact between pin6(power from AC fuse) and pin 1 (back light ground)? That would have put power directly to the dash light dimmer (rheostat), which grounds to the white-black (ground #IE, India echo) wire which attaches to the body in the kick panel.
The AC harness is IG1 (India gulf one), not certain but I believe the body side is the female (right) one.
`OK, so following your advise on last post, the pdf file did not show a 1g1 plug. However I did find a similar plug that was plug as part of the 3 to 1 plug. upon testing, I found a open circuit between the pin 9 of ig1 and pin 6 of a14.
ok that's one burnt out or cut wire found. The start of that wire is at the downstream side of the AC fuse, relay block #3 (right kick panel) pin number 2. So do the continuity resistance check rb3 pin3 to A14 pin 6, and rb3 pin3 to IG1 pin 9.
In fact let's start using the resistance check instead of just continuity, gives a better view of damaged wires.
Originally Posted by Dalgozy
Your advice would be to replace this wire. I don't like to second guess anyone, but, in this case I am. Something has caused the white wire with black stripe to melt and constantly blow 10 amp fuse. A open circuit wont cause this. Only a short will.
Can never be overly safe with electrical problems, please do "second guess" I've been known to babble aswell as assume the mechanic(you) knows more than they might. Anytime you have questions comments or concerns fire away. We've all heard the "only stupid question" rule.
The first task is to identify and list the damaged wiring, then to repair or replace it, and finally to diagnose the components are safe to reconnect
Originally Posted by Dalgozy
I have completely removed everything from radio, relays, everything that could of caused this wire to over heat. I even ran a wire to compressor clutch with no issues.I strongly know that I have to cut into loom and find everyplace the over heated wire has melted into another and remove the burned wire and replace, and insulate other wires and then figure out the cause of the problem. I am an electronics tech by trade but with health failing, I've forgotten more than what I've learned. I have concluded what you have said is correct that the problem lies between the fuse and the ac switch. I am honestly leading to a shorted diode or transistor in the amplifier board that initially caused the problem. I appreciate all the help and think you have led me in the right direction to find faulty wiring however the underlying cause is the most important part I now need advise on. Everything we spoke of checks out ok however the amplifier hasn't come up as a cause. If I'm going in the wrong direction, please let me know. PS. If my spelling or grammar is not correct either, please let me know.
You are doing great work and are a pleasure to work with.
Give me a bit to wrap my head around the control box (AC amplifier) logic and maybe find an internal schematic.
AC switch (control panel)
1-3 continuity (the back light) this checks OK as you mentioned above
4-5 & 4-6 continuity, while the switch is on
(This one is not in the FSM, but alluded to in the EWD)
Diode test, pin 5 (red meter lead) to pin 4 (black lead) continuity, reverse the leads black to 5 red to 4 no continuity.
..
magnetic clutch coil (engine bay, the single wire off the compressor)
Coil lead to ground, 3.6 ± 0.2 ohms.
..
ac amplifier, I am concerned with the testing process here. Attaching the PDF page.
inspect AC amplifier on wire harness side.
Test conditions.
Ignition ON, temp lever MAX cool, blower ON
(it doesn't say so but assume AC switch off to begin with)
7-8 continuity
8-ground continuity.
.. these next ones are supposed to be voltage checks by the book
3-8 continuity, regardless of switch on/off
.
4, is down stream of the switch and has power applied with the switch on
6, is the engine run signal from the tachometer output of the ignitor, has 10+ volts engine running.
9, grounds the AC idle up vacuum switch valve.
. Resistance checks
2-5, lever to MAX cool, near zero ohms
2-5, lever to MIN cool, near 3k ohms.
5-8, constant, ~1.5k at 77°
...
if the circuit is as specified, try replacing the amplifier with a new one. If the circuit is not as specified, inspect the circuit connected to
...
Just a shot in the dark it's the clutch coil shorted out. You said you replaced that wire?
.
Last edited by Co_94_PU; 01-18-2017 at 06:38 AM.
Reason: Formatting
Only the letters ac are lit. Also, can you tell me the final end of where the white with black stripe wire coming off ac 10 amp fuse ends? The ac light is on anytime headlights or parking lights are on and it goes off when I turn off lights. Sorry for so many questions! I have lower dash fully apart to check anything needed. Since everything is operable in vehicle, I have been considering replacing white and black striped wire instead of cutting out loom covering just to find end of wire. I know it must be melted into a wire in loom since all ac units are unplugged under dash and still blowing fuse but its obviously not affecting anything else since all is working as it should. Also radio is out and unplugged. I cannot figure out how to remove the ac/heater controls although the ac switch is out and I've even pulled plug from rear of heater controls to be sure of no melted wires there and all look fine.Thank you for your help in this so much!
I did not replace clutch wire, I ran current through existing wire and ran ac for about 30 minutes with no problems, wire never even got warm. And how the heck do I remove ac amplifier! it doesn't seem to have enough room to slide up out of box because of bolt sticking out of heater/ac box! I will dremel the box around it before removing ac/heat box if need be!
Only the letters ac are lit. Also, can you tell me the final end of where the white with black stripe wire coming off ac 10 amp fuse ends? The ac light is on anytime headlights or parking lights are on and it goes off when I turn off lights. Sorry for so many questions! I have lower dash fully apart to check anything needed. Since everything is operable in vehicle, I have been considering replacing white and black striped wire instead of cutting out loom covering just to find end of wire. I know it must be melted into a wire in loom since all ac units are unplugged under dash and still blowing fuse but its obviously not affecting anything else since all is working as it should. Also radio is out and unplugged. I cannot figure out how to remove the ac/heater controls although the ac switch is out and I've even pulled plug from rear of heater controls to be sure of no melted wires there and all look fine.Thank you for your help in this so much!
Originally Posted by Dalgozy
I did not replace clutch wire, I ran current through existing wire and ran ac for about 30 minutes with no problems, wire never even got warm. And how the heck do I remove ac amplifier! it doesn't seem to have enough room to slide up out of box because of bolt sticking out of heater/ac box! I will dremel the box around it before removing ac/heat box if need be!
Great website ate my text while I was not looking and didn't offer to auto restore...
Ground map attached.
Amp has a plastic cover with maybe one screw at the bottom, remove the screw or pry the cover off from below and it should slide out.
Try a web hunt for "Toyota.4Runner.1990.1995.zip", it has the FSM and EWD inside. Otherwise the web.archive.org should still have Nathan's copy of the 93 manual but not the EWD.
I do appreciate all the help but I can no longer really follow a schematic. If someone can just tell me exactly where the white with black stripe wire coming off ac relay ends at, I think I can figure things out from there. Thanks
I do appreciate all the help but I can no longer really follow a schematic. If someone can just tell me exactly where the white with black stripe wire coming off ac relay ends at, I think I can figure things out from there. Thanks
Originally Posted by Dalgozy
I realy don't want to start stripping away loom covering but it looks like best idea to see if melted wire is shorting against others.
Yeah it might just be best to grab 20 ft of new cover and some zip ties. But I can try. Which relay? Can you attach photos?
There is the "AC cut relay" in the dash but it doesn't have a white w/ black stripe.
Two relays for the condenser fan speed control, these are connected together with the condenser fan resistor by a white wire with a black stripe.
There is the white black wire on IG1 pin 10 which connects to the amp and blower switch and terminates in the left kick panel.
I'm thinking it's that last one? You'll only have to chase it across and down the dash depending where it's melted through. In the ground PDF above its the second page and connects a metric ton of crap...
Don't know how to attach photos, Hardly know how to use the internet! Its the relay next to the heater relay on pass side kick board. If I knew the other end. I could snip both ends and tie the heater and ac grounds together, then determine the cause which I believe to be the ac amplifier. I still don't see how to remove amplifier though as there is no screw and casing is part of heater/ac housing molded in. But still best to remove loom to see actual damage although nothing else is affected. Its just so tightly tucked up there, it doesn't seem easy! I believe in having electrical things original, otherwise I would tie the condenser fan to engine fan and runing a line to a 12 volt homemade board going to the ac switch and nobody would notice the differance in the Texas heat! But I do want it proper!.
Look at the condenser fan circuit. There is a relay for this fan. I see that as the compressor clutch is turned on, current goes from the ac amp to the condenser fan relay to ground. I see a black and white wire coming from this relay. If this is the relay you are talking about with the burnt wire, look at that fan and make sure you don't have an issue with it. That could sure blow a fuse. Check that relay as well. Current would have been coming from the amp so if it's getting to the relay ok, it may not have anything to do with the amp. Look downstream for your problem.
As a mater of fact. If the black and white wire is on the fan relay, then you could almost rule out the amp and start troubleshooting that fan circuit, including the relay itself and it's ground. The schematic shows that the ground and the relay have nothing else between them far as I can tell but I'm tired and ready to call it for tonight.
Strange, because if thats the case the wire that is way overheated is the ground on the front heater relay though Its operating just fine.so what is causing ac fuse to blow instantly when fan control is turned on when ac switch is in the on or off posision and/or when ac switch is unplugged and everything ac wise is disconnected under dash?????
Strange, because if thats the case the wire that is way overheated is the ground on the front heater relay though Its operating just fine.so what is causing ac fuse to blow instantly when fan control is turned on when ac switch is in the on or off posision and/or when ac switch is unplugged and everything ac wise is disconnected under dash?????
It's a fault in the relay probably.
You are going to have to tear into that wiring bundle containing the blue-white wire we found the open circuit on. ig1 pin 9 to a14 pin 6. While you are repairing that one also inspect the red wire from relay pin 4 to AC fuse pin 1 and relay pin 4 to blower motor pin 1.
I think the blue-white got damaged and/or connected to a power wire, or it was blower switching off (coil discharge). This created the direct path to ground thru that relay, pin 4 to pin 2.
Pin 4 to pin 2 of the relay is supposed to discharge the coil field collapse when the blower is switched off.. maybe it just exceeded its working life?
With the new blue-white, new red, and new relay. The system should be functional as designed again.
01-17-2017, 08:23 PM
