Thread: ECU in "sleep" mode?

Ok, so a few months back I put a jwt ecu in my car. The plan was that when my turbo set up was complete, I would send out the jwt to get reprogrammed and I would put the stock ecu back in the car so I could get around while the jwt was getting reprogrammed. When I went to put my stock one back in, the car would crank, but would not start. I talked to a few people and have heard that ecus can go to sleep after they are unplugged for a while. I was wondering if our ecus do this, and if so, how to "wake them up." I really dont want to buy another stock ecu just to use it for 2 weeks, not to mention I am dying to turbo my car already. Thanks.

Make sure you've got the harness plugged in entirely.

Its entirely plugged in Iv'e unplugged and replugged the harness multiple times. I even threw the jwt back on and it fired right up.

Try disconnecting the battery?

yep tried it. I don't understand how the ecu couldve gone bad from sitting in my closet. Its not like I left it in the shed or something.

Did you install bigger injectors or anything of that sort?

Nope haven't touched them or the maf. The setup is exactly as it was when I took it out, stock.

There is no "sleep mode" in the ECU. Turn the ignition switch on (not cranking), does the fuel pump cycle on then off after about 5 seconds?

Yes the fuel pump does cycle on. Idk I heard from 2 people (and yes, they do know their stuff) that some ecus "go to sleep" after being unplugged for a while. They also said something about cycling the key between on and off to wake it up. I gotta try and talk to them again tomorrow; i was just curious if anyone on here has heard of this/dealt with this. I just really don't see how an ecu can go bad when it only sat in my closet for like 3-4 months.

95b14, if dfddfd2 said there is no ECU sleep mode on our ECU's then there is no sleep mode on our ECU's. Your friends might know there stuff, but every car is different.

Something else is wrong with your ECU, or harness. Take the cover off the ECU and look for water marks.