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Toyota Ignition Switch Voltages

Boomtacoma01

3rd Coast
Joined
May 26, 2020
Member Number
1500
Messages
406
Loc
Houston
I had an issue with a total loss of power on my last wheeling trip with my 2RZ swapped 85 Toyota. I experienced power loss on 2 different occasions.
I ended up having to hotwire the ignition switch to make it run. On the second occasion, the alternator stopped charging.

I thought it would be a simple ignition switch change to fix the issue. I was wrong. I was able to get it back home.

I did change the 30 and 40 Amp Fuse Links in the under hood battery box as they were giving weird values.
Ive checked every fuse and relay (3times)

Im at the point now it has to be a short somewhere. I will try the hot wire method again after I clean up my trail splices.
I have power to a few of my gauges and fans. nothing else. no starter click, relay click or engine turning over whatsoever.

Im going to tear the dash out and check as much Wiring as I can in the main harness and accessories.

My question is what voltages can be measured on the back of the ignition switch as the key is put into its various positions?

ACC On Start
AM1
AM2
Acc
IG1
ST1
IG2
ST2

This is a pic from I found online which I can probably cross reference to an extent with the pins that are labeled.

ignition switch wires.jpg
toyota-1985-wiring-diagram-engine.jpg
 
Last edited:
So I cleaned up the hotwired Ignition switch to see if the it would fire up again.. and it did.
 
The black wire with the toggle is 12v feed directly from the battery behind the driver seat. It is spliced in to power the ACC and IG1 or AM1 (cant remember right now) then the 12v it touched to the ST1 terminal and it starts.
 
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