KennyJ Posted May 13 Report Share Posted May 13 I had a customer car in last week, ecu didnt shut down while the car was off. did some measuring , the pin that triggers the ground side of the eccs relay had 6v on it , so it was sort of conducting. depinned , ecu shut down put ign-on wire to DI , connected eccs relay ground to injector 6 , changed settings , connected diode betweend DI and eccs fed 12v pin. that worked noticed the electric fan started working , injector 5 connected to ground when ecu was shut down, moved feed from fan relay tot switched 12v all good car was build up again over winter , intruducing these problems. i suspect the customer welded on the chassis with the ecu connected. am i correct to think injector outputs and ignition outputs normally dont connect to ground when ecu shut down ? i know aux outputs do connect to ground Quote Link to comment Share on other sites More sharing options...
Adamw Posted May 13 Report Share Posted May 13 No outputs connect to ground when the ecu is off, they are all "open" in the unpowered state. But aux outputs do have a flywheeling diode that is connected to the 14V pin so if you have voltage on an aux when the ecu isn't powered then you will be feeding the ecu and everything else that is connected to the +14V pin circuit through that aux. This is what we refer to as a "back feed". Injector 5 doesnt have a diode so cant backfeed, the only logic I could apply to the fan continuing to run would be the ecu wasn't actually off, the ignition switch might have been off but there is some other backfeed keeping the ecu powered up. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.