Check and Replace ECU
First check the ECU ground circuit. If it is faulty, repair it. If it is normal, the ECU could be faulty, so replace the ECU with a known good one and check if the symptoms appear.
Measure the resistance between the ECU ground terminal and the body body ground.
Resistance: 1 Ω or less
- Disconnect the ECU connector, check the ground terminals on the ECU side and wire harness side for bend and check the contact pressure.
This guide is based on the book edition Toyota (RM502U, 1997)