Is there an ACC wire that doesn't shut off during start?

[GrimJack]

I'm trying to find a spot to wire in my MAFT-Pro power lead. I want something that's on when the ignition is set to ACC, but doesn't turn off when the starter circuit is activated.

I used to have it wired to my ECU power, but that's on all the time, regardless of where the key is.

However, if the power shuts down when the starter is engaged, the car is hard to start.

I'm not looking forward to building a delayed switched relay, which is the only other option I can think of offhand.

 

[jetjock]

Offhand I can't see how you'd do that with stock wiring Grim. Why do you need it to be ACC? Why not IG1 or 2?

Do you still have your clutch safety switch? I ask because I use mine to do a bit of similar electrical shenanigans ie; seat belt interlocks and some stuff that deals with my carjacking system.

 

[GrimJack]

Actually, I guess I don't need it to be ACC, I just need something that's always on when the key is in and in the run position... hmmm... IG doesn't cut out when the starter is active. Why didn't I think of that?

Thanks JJ, I think you've solved it!

PS: I only kindof have my clutch safety switch - it's still physically there, but it's disconnected so that the remote starter will function. I guess it would have to get power during the crank cycle too, or it wouldn't work very well.

 

[jetjock]

Yeah, IG2 feeds the injectors and coil packs. IG1 feeds the ECU. If they were killed during cranking you'd have hard starts for sure

 

[IJ.]

LMAO @ JJ :aigo:

 

[CRE]

I'm feeding my MAFT Pro, WB and MAP sensor via a relay which is energized by the signal at +B1 of the ECU harness.

 

[jetjock]

Ha! I was racking my brain trying to remember. It was you

That'll work. Didn't you have some sort of issue regarding a boot up delay or something? How did you resolve that?

 

[GrimJack]

I'm feeding my MAFT Pro, WB and MAP sensor via a relay which is energized by the signal at +B1 of the ECU harness.

Isn't B1 constant 12v? As in, even when the ignition is off?

 

[jetjock]

You're thinking of BATT. It's hot all the time for keep alive purposes. +B and +B1 (connected together at the ECU) are switched by the EFI Main Relay. They're what power the ECU up when the key comes on. You can use that line, M-Rel, IGSW (ignition switch), IG1 or IG2. Lots of ways to get switched power. IG1 powers most everything in the car ie; radio, cig lighter, wipers, etc.

Just be sure you don't tap downstream of a fuse that will kill the Maft for some minor reason. For example you don't want a shorted wiper motor, turn signal, or cig lighter to shut it down. In other words it's not wise to wire EFI components to non critical circuits or put non critical items on EFI circuits. That's why CRE's method is good...he's got an EFI component tapped into EFI system power.

While +B it can be found lots of places under the hood the only place you can pick it up inside the cabin is at the ECU. The reason for that is ECU wiring and sensors are routed through as few junction blocks and connectors as possible for increased reliability.

IG1 on the other hand is all over junction block #1 in the drivers footwell. Look below the ignition switch:

http://tinyurl.com/2dd2jc

See that little B-Y jumper? A good place to tap IG1. Otherwise use the hot side of a fuse in the block. Myself I'd tap into +B1 or the main relay circuit. Whatever you do be sure to install a fuse at the tap point for the Maft.

 

[GrimJack]

That's odd. I just checked mine, and B1 is always on. This is where I had my MAFT wired in previously, and I didn't like the idea that it was always powered on.

Makes me wonder what has been done to my wiring prior to me owning it!

Tapping into IG1 / 2 is dead simple for me, both of them are already cut for the remote starter installation. And as an added bonus, the alarm doesn't just kill the starter circuit, but the IG2 line as well.

 

[jetjock]

Hmm....that is odd. If +B is always on that means (assuming stock wiring) the main EFI relay is closed. That shouldn't happen unless the key is on.

+B is also found on the diag block. It's the terminal used to jumper the fuel pump. If you get power there to ground with the key off something is definitely wrong.

 

[GrimJack]

I'll check the diag block when I get home tonight.

 

[CRE]

Hey JJ, yeah, that was me. I really haven't gotten around to working on the boot delay issue.

I'm using a relay to power the MAFT Pro and wideband (with an inline fuse) because +B1 wasn't too happy about the load my WB put on the circuit... or I guess I should say the WB wasn't happy during the warm up and calibration cycle.

 

[shaeff]

^ i'm assuming you used the +B1 to trigger the relay, correct?

 

[CRE]

^ i'm assuming you used the +B1 to trigger the relay, correct?

I'm feeding my MAFT Pro, WB and MAP sensor via a relay which is energized by the signal at +B1 of the ECU harness.

Yup, I suppose my statement wasn't as clear as it could have been.

 

[CPT Furious]

Grim,

Is there a specific issue you were having with the Pro? Mine powers up quick and I haven't had any hard starting issues since I replaced my battery...whole other story there!

My brother didn't know Toyota had a key lock button you had to press to get the key out and being the beefy guy he is, broke the mechanism holding the key in. So this led to uneducated individuals being able to remove the key with the car in the ACC position and depleting the battery numerous times. They tend not to like that much. So after new battery install, everything works great!

The Pro stays powered up for a few seconds after shutdown then powers off.

 

[GrimJack]

Grim,

Is there a specific issue you were having with the Pro? Mine powers up quick and I haven't had any hard starting issues since I replaced my battery...whole other story there!

My brother didn't know Toyota had a key lock button you had to press to get the key out and being the beefy guy he is, broke the mechanism holding the key in. So this led to uneducated individuals being able to remove the key with the car in the ACC position and depleting the battery numerous times. They tend not to like that much. So after new battery install, everything works great!

The Pro stays powered up for a few seconds after shutdown then powers off.

You probably have the power wired up differently in yours - or your B1 wire at the ECU behaves properly.

This is a bit of a story, so sit back and relax.

Originally I had it wired to B1, but the MAFT Pro was on all the time. I didn't like that much, so I wired it to an ACC line. As soon as I did that, it was hard to start the car. Unfortunately, I'd changed the wiring at the same time as I did a bunch of other stuff, (rebuilt my CPS, mucked with my fuel pressure, redid all the temp sensors in the thermostat housing, replaced my Zeitronix wideband with an Innovative Motorsports unit, added a remote starter, replaced my Compustar alarm with an Autopage unit, replaced the battery & alternator, and wired in both starter and IG kills on the alarm) and it was getting cold out in the mornings, AND it was only hard to start when dead cold, so it took me months of trial and error to figure out the source. The power source was extremely low on the list of things to check, mostly because I'd soldered the wires, then shrinkwrapped them, then taped them, and I wasn't looking forward to pulling all that back apart.

When I moved it back to B1, the hard starts vanished instantly, it went back to what I was used to, firing up right away on the first try.

But now it's back to being on all the time, so I was looking for a better place to wire it. If there is something wrong with my B1, I'll just fix that instead.

 

[jetjock]

That'd be the best plan of attack.

CPT must also be tied into +B. The ECU keeps the EFI main relay (and thus +B) alive for a few seconds after the key is switched off so it can home the ISCV which is also powered by +B. The ECU then commits suicide by dropping the relay out. Expect to see the same although what advantage it offers I dunno. You'll at least get a visual indication the circuit is working right.

 

[IJ.]

That'd be the best plan of attack.

CPT must also be tied into +B. The ECU keeps the EFI main relay (and thus +B) alive for a few seconds after the key is switched off so it can home the ISCV which is also powered by +B. The ECU then commits suicide

by dropping the relay out. Expect to see the same although what advantage it offers I dunno. You'll at least get a visual indication the circuit is working right.

 

[jetjock]

::hang::

Since it's already happened down there happy new year!