Possible ABS disable switch project for First Gen

OK, this could be a totally reasonable way to go. I actually like the side effect it has of turning on the ABS light on the dash. Will need to find the wire to switch - how easy will this be for me to find the low amperage side wire?

 

In the EWD you posted. If shows only one 60A fuse feeding the ABS ECU. Is that the case with your truck? Should have a diagram on top of the fuse box. Can you check? Look for ABS 60 / ABS 30.

 

Will have to check. Unfortunately*, away from the truck for a week right now.


*unfortunately is a bit of a misnomer. We are enjoying some time in Hawaii this week (and I love seeing all the Taco's here)

 

That's sick!!
For that much work a straight axle seems like a better way to go.

 

Which fuse are you talking about? All the ones I see we effect other components like the ECU causing a fault code.

 

There are two ABS fuses under the hood. The smaller of the two is easily removed and causes no other effects than disabling the ABS system and turning on the brake warning light.

 

It looks like according to the diagram the 2000 doesn't have that fuse were the 2004 does. 30amp fuse

 

With the OP's diagram you could just run a switch to interrupt the wire coming out of the detection switch.

 

Better yet if you interrupted the 2 wires right before they went into ABS unit. That way every thing else would see the switch open but the ABS wouldn't. Or vise versa closed. I'm unsure what position switch is in, in 4lo

 

I don't think those solutions will work. By putting the switch in series, you're essentially making it so that the ABS ECU won't get the signal from 4LO that 4LO is "on." Since ABS doesn't know 4LO is on, it will leave ABS enabled (whenever the switch is interrupting the circuit) - so ABS will either "work like stock" (when the switch is closed, b/c then you have the original circuit) or will "work when stock wouldn't have" (when the switch is open).

Am I missing something?

OK, checked a 2000 Tacoma in Hawaii since there are hundreds of them. Only has a 60A ABS breaker. No smaller ABS2 breaker to switch :-(.

 

Then use a DPDT switch with one side grounded. So you could interrupt it or ground or complete circuit which ever you want.

 

Use I diode before switch so the rest of the controllers don't see what the switch is doing if need be.

 

Yes multi-connection splice the EX12 wire, add a diode up stream to the other circuits. Your MCS and diode keeps the circuit intact as intended (as long as your kill switch isn't engaged). Now you have a wire to a fix to your SPST switch then ground the other end of your switch to the chassis for the ground. Once the switch is switched you've just stimulated the 4LO detection switch, assuming there's not a ABS Ecu protocol for a specific resistance needed from the switch. If that's the case, simulate it with a resistor.

 

I can see why now. Pulling the 30A fuse is popular. Haha.

 

I think what you're suggesting is to do what I had in the original post, except that

1. instead of having a +12v on the other side of the switch, have ground
2. I may not need the resistor on the spliced (grounded + switched) wire

Here's the diagram for easy reference:

 

Yea in the full circle of things we end up back to that.

 

Yeah, fun times. What's the right way for me to figure out if I want +12v or ground on that switched branch. (i.e. what do I measure before I make the change?) Is it:

Truck in 2WD - measure voltage across pin 14 on ABS ECU and chassis (ground)
Truck in 4LO - measure voltage across pin 14 on ABS ECU and chassis (ground)

Then:

If 2WD voltage is 12V and 4LO is 0V, then the switch goes to ground.
If 2WD voltage is 0V and 4LO is 12V, then the switch goes to 12V.

...and how do I know if I need the resistor? (try it without, and if that doesn't work, try it with? )

 

Try without first. I don't think it would be 12volts because it would be short to ground. Would the diode be reversed then in diagram?

 

The answer was in pinout of FSM. DUH SHOULD HAVE LOOKED ALONG TIME AGO. pin 14, 10-14 volts needs resistor