Did I Fry my ABS ECU? No, no I did not.

EDIT: Problem solved, it was Ig1 No 2 fuse and @Grossomotto is my new BFF.


It all started when I was trying to make my ABS kill switch fancier. I wanted it to be activated by a 5 pin relay whenever I turned on my ARB locker. I thought it would be simple enough.

Basically, the current kill switch is an ON-ON switch. Either the OEM circuit is connected and ABS works, or the circuit is grounded and ABS is disabled. It tricks the truck into thinking the OEM locker is engaged.

I wanted it to be activated with a 5-pin relay. Either the relay is on pin 87a and ABS works, or I turn on my ARB and it flips to pin 87, thus grounding the wire and disabling ABS.

The wire in question is in connector IB1, pin 4. Light green wire.

Now here's where things get hairy. I wire in the relay. Life is good. I activate the locker and the ABS light comes on as expected, but no diff light. Then things get fucky.

Here's where I'm currently at.

-speedometer doesn't work (Even though speed gets read from t case output on my truck and has worked in the past with a torn ABS wire.)

-windows won't roll down

-Clutch start cancel doesn't work

-When I reconnect the wire back to OEM configuration, the ABS, parking brake, and DIFF LOCK lights are illuminated.

-If I disconnect the OEM wire, the DIFF LOCK light turns off


Things I've tried.


-I tried to read ABS codes by jumping some OBDII pins. I have done it in the past and it worked great. Now, the ABS light just stays solid.

-Also tried resetting ABS codes, no luck.

-Disconnected negative terminal for a bit.

-Checked every single fuse with a multimeter for continuity. Found one blew and replaced already.

-Will have my mechanic friend put his multi thousand dollar scanner on it when I get a chance.

-Truck still starts and drives completely fine otherwise.

It SEEMS like a fuse is out somewhere because of the windows and clutch start cancel switch but I've checked them all at least once. Any help is appreciated.

 

As I sit here staring at my diagram, I realize I had the two green wires reversed, meaning I grounded out the wiring harness side of the green wire. Which I believe is normally +12v, therefore shorting out something somewhere. The question is what.

 

Did you burn up a relay somewhere?

Also you’ve been messing with the grounds. Check they are all tied down. A bad ground can give you strange results.

 

Why wouldn’t you want to keep the ability to kill ABS without engaging the locker?

 

If I did, I wouldn't know where to begin. I did just go swap in a known good relay for STA because that has the clutch start cancel on it's circuit with no dice. As far as grounds, I haven't been messing with any OEM grounds. The only OEM wire I touched was that single green wire.

That's beside the point and not a helpful contribution to the thread.

 

Boy, was I hangry when I first replied. Sorry.

I didn't add this to the OP because I didn't want to confuse anyone. In reality, I used to have this kill switch installed. I removed it when I was troubleshooting ABS issues, which ultimately was a torn sensor wire. I left the switch uninstalled and put the wiring back to OEM.

What spurred me to restart that project was wanting the diff lock light on the dash to illuminate with my ARB. Rather than only illuminate the light, I thought, "Hey, that'd be cool if it killed ABS too." That's when I went to reinstall the kill switch in a fancier manner. And here we are.

 

Did you by any chance remove fuses and put it back .When installing stereo added add a fuse and but it back in wrong slot .Went through wiring and every thing was good .Looked through TW and found this pic. I put Ign 1 fuse in empty slot . Also put add a fuse in different slot .Didnt realized I put it on Ign 1

 

Good thought, sometimes it's the simple things. No luck though, everything is in the correct spot and correct amperage. I just went and double checked.

 

here is my contribution.... @6 gearT444E is good for these types of threads

 

Well on the plus side, I can still get in and out of 4HI and 4LO. I can procrastinate on installing my FJ case until I sort this out.

 

Double checked IGI No. 2 fuse?

 

Pretty sure I've quadruple checked it at this point, both visually and with a multimeter.

 

YOU WANNA HEAR SOME BULLSHIT. I went and checked AGAIN. And what do you know, it was blown again. I swear on all things holy that it checked out with a multimeter but like 10 minutes ago. I just put a new fuse in and everything is fine.

 

I was just reading this thread with some similarities.

https://www.tacomaworld.com/threads/strange-problem-with-ig1-no-2-fuse.553082/

One member said, I'm not sure if it would be of help.


"I started with power windows .... Yes, this fuse is in the circuit - but NOT the power to the Windows - just power to the relay. This Relay gets power from IG1 No.2. Via the Body CU unit. I'd test the 12v power from the fuse to the BCU, The Ground from the BCU to the Bat NEg. and then the Power out from the BCU to the Pwr window relay coil AND the Relay coil to ground. I'm thinking that this is so widespread that a ground point that ties to multiple control modules is frayed/bad and heats up do the high resistance and drop the 12 v to much lower. ???"

 

Eyyy, got my wires right and my mod works as intended.

 

Sweet, keep a bunch of spare fuses with you.