# Cutting power to ECU **URL:** \ **Category:** SON240sx Automotive\ **Created:** [May 9, 2008, 8:24am UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368 "2008-05-09T08:24:39Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![kingtut](https://avatars.discourse-cdn.com/v4/letter/k/c2a13f/32.png) [@kingtut](https://forums.speedlife.net/u/kingtut)\ **Post date:** [May 9, 2008, 8:24am UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/1 "2008-05-09T08:24:39Z")
Hey guys, i was thinking of coming up with a new idea for security for my car. I know it might not be the greatest idea…or easiest…but i wanted to come up with something new. So i was wondering if i could have a hidden switch which disconnects main power to the ECU. I was wondering if it was alright to do so and that i won’t loose data or anything like that…I was thinking to do this because if anyone tries to start it…it would be literally impossible…Any help on this matter would be greatly appreciated…please don’t flame me about how its stupid or what not…instead just give me ideas of what is better…I’m looking for something along the lines of a switch…Thanks guys. ---
**Author:** ![kingtut](https://avatars.discourse-cdn.com/v4/letter/k/c2a13f/32.png) [@kingtut](https://forums.speedlife.net/u/kingtut)\ **Post date:** [November 17, 2008, 7:44pm UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/2 "2008-11-17T19:44:41Z")
bump ---
**Author:** ![kimmerkaze](https://avatars.discourse-cdn.com/v4/letter/k/9d8465/32.png) [@kimmerkaze](https://forums.speedlife.net/u/kimmerkaze)\ **Post date:** [November 18, 2008, 1:18am UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/3 "2008-11-18T01:18:13Z")
just wanted to point something out… is there really a difference between putting a cutout for a fuel pump or an ecu? what i’m trying to say is the most important part for your security idea isn’t the actual idea itself but the hiding location. it doesn’t really matter what kind of switch you have…just more or less work in the end for the same purpose. if you want direction for your ecu cutout idea, look at the fsm ecu circuit and wiring first and see if there’s a spot you want to work out of… ---
**Author:** ![kingtut](https://avatars.discourse-cdn.com/v4/letter/k/c2a13f/32.png) [@kingtut](https://forums.speedlife.net/u/kingtut)\ **Post date:** [November 18, 2008, 2:32pm UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/4 "2008-11-18T14:32:16Z")
yea…i have an idea for the location of the switch …but i was just wondering if i can cut main power to it and turn it back on without any problems ---
**Author:** ![Gongster](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/gongster/32/5615_2.png) [@Gongster](https://forums.speedlife.net/u/Gongster)\ **Post date:** [November 23, 2008, 8:20pm UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/5 "2008-11-23T20:20:11Z")
You might as well just cut power to the fuel pump. I don’t see the point in cutting the power to the ECU. The ECU has constant power running through it even when the car is off, so I would imagine that it wouldn’t be good to be cutting that power on and off on a regular basis because it just isn’t designed to. Any data stored in the ram of the ECU will be erased when the power is cut. ---
**Author:** ![Martino](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/martino/32/5674_2.png) [@Martino](https://forums.speedlife.net/u/Martino)\ **Post date:** [November 23, 2008, 8:45pm UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/6 "2008-11-23T20:45:15Z")
Have a switch cutting power to the sending unit. It’ll save you problems with the ECU going into any sort of problematic mode. ---
**Author:** ![nd4boost](https://yyz2.discourse-cdn.com/flex034/user_avatar/forums.speedlife.net/nd4boost/32/5627_2.png) [@nd4boost](https://forums.speedlife.net/u/nd4boost)\ **Post date:** [November 23, 2008, 9:10pm UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/7 "2008-11-23T21:10:52Z")
if you cut power to the ecu it will have to re learn all the fuel maps again every time you start it (it will run on default maps instead of previous actual running maps) i dont recommend this fuel pump is the easiest or with a sr cut power to the coil packs ---
**Author:** ![Hurricane](https://avatars.discourse-cdn.com/v4/letter/h/e9bcb4/32.png) [@Hurricane](https://forums.speedlife.net/u/Hurricane)\ **Post date:** [November 24, 2008, 7:13am UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/8 "2008-11-24T07:13:30Z")
Actually… if you wanna do something tricky with the ecu for security interrupt the “start” signal wire to the ecu. Or just cut the power to the ECU relay which is the primary on power not the backup power which is what the ecu uses to remember things such as idle and “fuel maps” and what not. ---
**Author:** ![sil8t](https://avatars.discourse-cdn.com/v4/letter/s/ea666f/32.png) [@sil8t](https://forums.speedlife.net/u/sil8t)\ **Post date:** [November 24, 2008, 8:03am UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/9 "2008-11-24T08:03:01Z")
fp cut off alarm detachable hub turn wheels all the way one way when parking somewhere. ---
**Author:** ![kingtut](https://avatars.discourse-cdn.com/v4/letter/k/c2a13f/32.png) [@kingtut](https://forums.speedlife.net/u/kingtut)\ **Post date:** [November 25, 2008, 7:29pm UTC](https://forums.speedlife.net/t/cutting-power-to-ecu/115368/10 "2008-11-25T19:29:14Z")
Thank you all very much, im gunna take your suggestions and put them to use. I appreciate all the help.