2007 ES intermittent start failure

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03-24-22, 02:17 PM

#16

mmcd

10th Gear

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Quote:

Originally Posted by mmcd

You are correct, I now have a 18 page rolled system diagram, i was able to do a little experimenting with the car:

The battery was down to 11.97v. The orange wire from certification ECU is probably either VC5 from the ignition switch or LIN from main ECU. After touching with 12v from battery: wire has a clip now one side had 2.25v declining to 1.97 over a few minutes and11.22 on the other. When connected 7.25v. Key fob would not open doors, no ignition light on depressing brake pedal even holding fob to switch.
Put car on charger, battery 13.18v, orange wire 2.35v and 13.21v with 8.2v combined. Ignition and door locks not reacting (no light or action).
Held fob to switch and got beep and white light on ignition
Minutes later got orange light and key not detected on dash
Tried touching fob to switch again, got green light and car started but still can't lock/unlock doors or trunk
Left car and got beeps about key missing, put fob on steering wheel and fault went away
Double checked by leaving car with fob on steering wheel then removing it through window
Turned off car and now fob works and engine starts. Battery charged up to 12.53 volts

Any thoughts on this strange situation?

Thanks

Additional data: I could use the fob to lock/unlock the doors today but the ignition light would not come on even with the key next to the switch. Wouldn't this imply that the certification and code ID ECU are working? The battery voltage was down to 12.08v. I got a reading of 5.4v on the orange lead, 11.1v. on one side and 1.19v on the other. Car will start if battery is at 12.53v but no light if 12.08v and loses key recognition by 11.97.