4x4 dbl cab tacoma build

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jonsangel

Senior Member
Apr 13, 2009
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Los Angeles
What does everyone do with the battery disconnect switch and the ECM power? Right now my switch disconnects everything but that also kills power to my ECM which resets the memory. My plan was to disconnect the battery whenever I'm not driving it but it would be nice if the ECM could keep it's memory.
 
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FlapJack935

Oh i Member
Jun 26, 2017
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New Mexico
What does everyone do with the battery disconnect switch and the ECM power? Right now my switch disconnects everything but that also kills power to my ECM which resets the memory. My plan was to disconnect the battery whenever I'm not driving it but it would be nice if the ECM could keep it's memory.
Run the ECM on its own kill switch? But i guess that doesnt solve the problem
 

85yota

TT Motorsports
Nov 18, 2004
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Santa Maria, CA
www.tt-motorsports.com
I wasn't aware that ecm needed power constantly or it resets. All I thought it needed power always for was for the obd2 monitors to not start over and if running a tuned ls swap or such you can kill power everytime and it doesn't affect how the motor runs. Someone correct me if I'm wrong but I would kill all power to a holley ecu and everything when power switch is turned off. Just like my old Tacoma and rangers I've done it to as well.

Sent from my SM-G965U using Tapatalk
 

jonsangel

Senior Member
Apr 13, 2009
1,444
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Los Angeles
I mean I could be wrong but i thought it wiped all the "learned" parameters like air/fuel ratios. It definitely kills the OBD stuff.

In the stock configuration, is the ECM B+ always on? I wasn't sure if that was it or if that drew too much current
 

dalandser

Junior Member
Sep 30, 2017
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I wasn't aware that ecm needed power constantly or it resets. All I thought it needed power always for was for the obd2 monitors to not start over and if running a tuned ls swap or such you can kill power everytime and it doesn't affect how the motor runs. Someone correct me if I'm wrong but I would kill all power to a holley ecu and everything when power switch is turned off. Just like my old Tacoma and rangers I've done it to as well.

Sent from my SM-G965U using Tapatalk
I mean I could be wrong but i thought it wiped all the "learned" parameters like air/fuel ratios. It definitely kills the OBD stuff.

In the stock configuration, is the ECM B+ always on? I wasn't sure if that was it or if that drew too much current
That's what I was thinking about as well for my vehicles since they idle high after the battery's been out for long periods of time.
 

jonsangel

Senior Member
Apr 13, 2009
1,444
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Los Angeles
Sometimes my motor will idle fine on it's own and sometimes it will only run with the throttle slightly open. I'm guessing it has to do with needing to be tuned. When it idles well, i can start it over and over with good results until I disconnect the battery and then it has a hard time learning a good tune. It sounds pretty good in both conditions. That being said, I am confident enough that I won't have to pull it so I'm going to start final assembly on the front. I think things are going to start coming together fairly quickly.

Pulled the 3rd to regear
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Finished the brake lines. I need to bleed them all and check for leaks still
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jonsangel

Senior Member
Apr 13, 2009
1,444
472
83
Los Angeles
I've still been having problems starting my truck through the dash wiring that I think I finally resolved. Hopefully this will help someone else. If I put the starter relay wire directly to my positive battery post the truck starts up fine. If I put the starter relay wire through my ignition switch and try to start it that way, the motor turns over but doesn't start. After doing some electrical checks I found out that my ignition switch drops power to the accessories, I assume so they aren't taking any power from the starter. I was using the accessory power to trigger the relay that feeds the fuse block that my ECM gets power from so basically it looses power whenever I go to crank it. DOH! Should be an easy fix but definitely ate up a few days trying to troubleshoot.
 

Do Dah

Senior Member
May 13, 2012
441
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Should have 12v, acc, on, and start terminals on the start switch. Move the ecm wire to the on terminal.
 
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jonsangel

Senior Member
Apr 13, 2009
1,444
472
83
Los Angeles
FINALLY!

I had to add a small always on fuse block and another relay but it finally starts through all the wiring and the key. It also runs great without needing to push the throttle like before. Not sure why that is. The Tach doesn't work for some reason so I gotta troubleshoot that too. At least the hard part is done

I finished regearing to 4.86. Thanks for the help @the bodj . It was about as much work as I was expecting. I got lucky and didn't need much adjustment.
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I started final assembly on the front end after checking the brakes and power steering.
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Got a solid start on the exhaust. Just gotta add the mufflers and mounting. I'm going to dump the exhaust just behind the cab and not doing anything fancy. I decided to do an H-pipe instead of an X. It sounds like it's a little better for lower end and much easier for routing
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