loeb

My stock '95 LS400 has this strange intermittent behavior.

Sometimes, when I try to start, the entire electrical system "goes dead" as I turn the key... no start, no lights, nothing. If I disconnect and immediately reconnect the battery, everything is reset and it will start right up. Happens every 10th start or so.

It is as if it is detecting an over-current condition and protecting itself by disconnecting from the battery... and disconnecting and reconnecting the battery resets it. The battery and alternator are new.

Thanks for any ideas on what might be causing this.

oldskewel

iTrader: (1)

Assuming you are checking carefully for clean, solid contact between the battery cable clamps and battery posts, and there are no problems with the battery cables, then ...

It might be an internal fault inside the battery. I have had that rarely over the years. Tough to find since it is an intermittent problem. What I do to help isolate battery-related problems is to swap batteries between cars in my fleet. If you have another car with a compatible battery, you might try swapping.

loeb

I have had this problem intermittently over the past 10+ years. Just recently replaced the alternator and battery because they both died. I have very carefully cleaned the battery/cable connections several times over the years. The intermittent problem persists.

Yamae

Do you feel any heat when you disconnect and connect the battery terminal?
If the terminal or the thick cable is warm, I worry about the solenoid in the starter motor not in a good condition. The copper dusts spread inside may be making a short pass and causing the problem. You can confirm it gripping the thick cable to the starter motor when the problem is happening or check the current using a clamp meter.