Fried ECU?
Instructor
Joined: Dec 2020
Posts: 105
Likes: 4
But if the other car battery is connected to the terminal wires, there is no need for current to flow through the bad battery. You use the jumper cables to connect the jumper battery to the power system, not the dead battery. I have jump started a skidder which had no battery of its own attached, the only source of power before the skidder’s alternator started providing it was the jumper battery.
That’s why one of the tests for an alternator failing is to jump start the car with the dead battery and see if it keeps running once the cables are removed. You are disconnecting the external power source, and if the charging system isn’t working, the car dies.
Under normal circumstances, the car should crank with jumper cables and a jumper battery in another vehicle. Continuing to run after the cables are removed is an entirely different story, though.
That’s why one of the tests for an alternator failing is to jump start the car with the dead battery and see if it keeps running once the cables are removed. You are disconnecting the external power source, and if the charging system isn’t working, the car dies.
Under normal circumstances, the car should crank with jumper cables and a jumper battery in another vehicle. Continuing to run after the cables are removed is an entirely different story, though.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 45
Likes: 2
From: San Diego
I have seen a battery with a shorted cell that had good surface voltage but would not allow amperage flow, even with jumper cables hooked up and the donor car running. You really should verify that the battery is good with a load test. You are currently guessing it is good because it is only 5 months old.
Drifting
Joined: Jul 2007
Posts: 1,294
Likes: 37
Being that the battery was having issues maintaining a full charge not too long ago, I’m of the opinion that the battery has a shorted cell. You can’t jump start such a battery. Disconnect the battery from the terminal and then hook up booster cables to the unattached battery leads. If dash lights up....you’ve found your problem.
Last edited by JimiHendrix; Jan 19, 2021 at 02:25 AM.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 45
Likes: 2
From: San Diego
Being that the battery was having issues maintaining a full charge not too long ago, I’m of the opinion that the battery has a shorted cell. You can’t jump start such a battery. Disconnect the battery from the terminal and then hook up booster cables to the unattached battery leads. If dash lights up....you’ve found your problem.
Race Director
Joined: Dec 1999
Posts: 10,230
Likes: 885
From: Alexandria, Virginia, USA VA
fysa when my starter motor selenoid cooked it interrupted power from the alt to charge battery and operating voltage went down to 9 volts
dash flickered out, and the car finally stopped running. Check to see that the main feed is not being fritzed there.
sounds like what happened to me.
dash flickered out, and the car finally stopped running. Check to see that the main feed is not being fritzed there.
sounds like what happened to me.
Thread Starter
Intermediate
Joined: Aug 2019
Posts: 45
Likes: 2
From: San Diego
Thanks for posting this, my fault I never posted the solution! Sure enough, the ECU was fried. Battery and charge system were all good, but the ECU wasn’t operating properly. Took it to Chevy to have them change it out, brought it to my tuner to have it retuned, and haven’t had a problem since. Unfortunately I am about to list the car for sale which I am super bummed about, but I have my eyes on a C7 Z in the near future😎
