No head/tail lights or turn signals, squirrel chewed ground at J4

The 9.3V which shouldn't be @ C11 pin 12, is somehow getting over to C11 pin 18, green wire, where it goes thru IJ1 pin 8 to ECU B5 pin 13.
Then it's going from B5 pin 13, to B5 pins 14 and 15 to the HEAD and DIM?
If that makes any sense, it sounds wrong?
If so, it would mean the white C11 plug is bad?
Or the white/black and green wires leading to it chafed and shorted?

 

When you are testing for voltage.
Where are you toughing you black lead of the meter?
The black lead needs to be on a body Ground.

We need to be sure you have no voltage on your ground wire.

With these weird voltage readings. I think maybe we have voltage on the ground wire.

Unplug B5.
Make sure the Head lights are OFF. The switch needs to be in the OFF position.

From battery + to pins 20 (pink) = 0v.
From battery + to pin 17 (Red/White) = 0v
From battery + to pin 13 (Green) = 0v

 

You need to understand that a voltage meter does NOT read voltage.
It only tells you the difference between voltage of the 2 leads.

Lets say you touch the Black probe of your meter to wire (A).
Wire (A) has 12v on it.

And then you touch the Red probe of the meter to wire (B).
Wire (B) has 5v on it.

Your meter will read 7v. Because that is the difference between wire A & B.
12v - 5v = 7v

A perfect example of this would be to tough BOTH leads to the battery + terminal.
The meter should read 0v.
You know for sure the battery is good, and it is charged to 12v.
But the meter reads 0v.

That's because BOTH leads see 12v.
12v - 12v = 0v

 

See post #162 above.
Doing that test should kill power voltage on C11 pin-12, when you unplug B5

 

Will do, back in an hour or so.

 

If you want. You can do that same test with the headlight switch ON.
You should the get 12v on all the readings.

Headlight switch ON = 12v
Headlight switch OFF = 0v

 

B5 unplugged, heads off, to (+)
pin 13- 0v
pin 17 (is pink)- 0v
pin 20 (is white/red)- 12v

unplugged heads ON
pin 13- 0v
pin 17 - 0v
pin 20 - 12v

B5 plugged in
pin 13- 1.2v
pin 17 - 1.2v
pin 20 - 12v

 

Hold on, pin 20 is white/red and runs drivers door lock, shouldn't I be testing pin 16, red/white = Flash To Pass Switch Signal from IJ1 Pin 10?

 

Testing pin 17 of B5.
Pin 17 of B5 goes to Pin 20 of C11.

But battery + to pin 17 of B5 should show 0v with headlights OFF.
And 12v with head lights ON.

 

Revised-

B5 unplugged, heads off, to (+)
pin 13- 0v Tail Light Switch Signal from IJ1 Pin 8
pin 16 (is red/white)- 0v Flash To Pass Switch Signal from IJ1 Pin 10
pin 17 (is pink)- 0v Headlight Switch Signal from IJ1 Pin 9

unplugged heads ON
pin 13- 0v
pin 16 - 0v
pin 17 - 0v

 

It shows zero both ways for sure.

 

Ok, forget about the parking light only thing, that was last night, maybe a relay was loose.
Tonight, pin 12 of the combo switch, when grounded with test light, = low, high, parking, flashers all work!
So there's some good news.

 

So now we need to locate where that wire is broken/chewed/corroded.

 

So the problem is J4 pin 6, or J5 pin 5, or the IC ground?
J4? If it was J5 or IC there would be many other problems?
The wire between switch and J4?

 

Where might I find J4 and J5? Around the parking brake area?

 

I would think if Ground Point IC was bad there would be a host of other issues but it's possible I guess, IC and J4/J5 look to be in the same general area.

 

Looks like IC and J4/J5 are behind the radio area.

 

I can see one, not sure if it's J4 or 5.
What do I have to remove to get in there, dash or just radio?

 

You might be able to pop out the A/C controls and see it.
It's easy to get out.....

Just pry out from the bottom of the controls.


Stick a small screwdriver in between the crack and pry out.

All 3 controls come out as 1 unit.

 

IC ground is right behind the AC controls.