I think it is the key tumbler because the electrical system stays on even in the acc position

When you say ignition, do you mean the key tumbler assembly or the ignition starter switch at the base of the steering column.

Ignition key cylinder tumblers are worn out!
Time to replace the cylinder.
Help prevent this from happening again by lightening your key ring load. A heavy key ring puts constant pressure on the lock tumblers and wears them down to eventually deform and prevent the tumbler cylinder from turning.
Most people employ the philosophy, "if it jams, just force it", which bends the weakened lock tumblers and hastens destructive wear.

Alas, the old worn keys indicate a lot of grit has been pushed into the intricate key tumbler pins. They were/are most likely badly worn and the mechanism now jammed with particles worn from the tumbler pins etc. I strongly suggest you contact a local LOCKSMITH who is familiar with that particular system for advice and assistance. The lock tumbler will have to be removed and replaced. THAT may not be possible unless the key can be turned to the correct position for that extraction. This COULD turn into a major expense (big damn deal) involving drilling and cutting things apart (properly) and removing the steering column to fix.

No ignition key is designed to stay in START position. The key tumbler is equipped with a spring that will bring the key back to ON position once you release the key after starting. If you mean that it does not stay in ON position, then the tumbler may overshoot it's position. Try spraying some anti-rust or Wd40 into the key hole and insert key and turn the key from left to right a few time. If it does not work, you may have to get an auto electrician to look at the electrical switch that is attached to the back of the key tumbler.

hi jerome
I have the procedure for Toyota auto lock, is worth to try it
AUTOMATIC LOCK SETTING
1) Step in the vehicle and make sure that all doors are closed completely
2) Insert the key into the ignition key cylinder.
3) Wait for more than 5 seconds.
4) After turning the key to the ACC position, turn the key from the ACC to the
ON position 5 times within 10 seconds (Last position : ON).
? Status Monitor LED will illuminate for 30 seconds.
Note : In case you implement 6 times or more by mistake,
action steps 6)-8) you made will be canceled.
Please retry from step 2).
5) While the LED is illuminated :
• Open and close the driver's door 2 times.
• Turn the key to the ACC position.
? LED will continue illuminating.
? Indicator lights will flash 2 times.
Ignition controlled door lock ON :
6) While the LED is illuminated:
• Open and close the driver's door 1 time.
• Turn the key ACC-ON-ACC 1 time (Last position : ACC).
? Indicator lights will flash 1 time.
? LED will extinguish.
Ignition controlled door lock OFF :
6) While the LED is illuminated :
• Open and close the driver's door 2 times.
• Turn the key ACC-ON-ACC 1 time (Last position : ACC).
? Indicator lights will flash 2 times.
? LED will extinguish.

if ou do not have the key, look at the replacement lock there'll be a tab which recesses when the key is turned to acc or on position. It is that tab which prevents you from removing lock cylinder it has to be forced into a recessed position or drilled to where the cylinder can removed. If u do then locate tab turn key to acc or on and push tab to recessed position and remove cylinder.

to remove ign switch you must remove lower dash panel turn key to acc position and push ign lock at bottom of ign assem located about 1 inch down from front of key cylinder you will see a hole using a pick tool push up and pull out on key to reinsert key must be in acc position please rate this info

BFC that body function controller. BFC batt fuse controls .the body function controller .its part of the PCM.the BFC controls anti theft system. your interior lights -drl lights- radio -door locks.if your check engine light is on take it to dealership.because your BFC and PCM works together. your car could shut off. that unsafe.when you on a busy highway.you have electrical problem.not a home fix.

REMOVAL

1. On models equipped with airbag, disarm airbag as described under MAINTENANCE PROCEDURES/AIRBAG SYSTEM DISARMING.
2. On all models, disconnect battery ground cable.
3. Remove ignition switch as described under STARTING AND CHARGING SYSTEMS/COMPONENT REPLACEMENT AND REPAIR PROCEDURES/IGNITION SWITCH.
4. Remove key light case from lock body, if equipped.
5. On 1989 Accord models, place ignition lock cylinder in the ACC position.
6. On except 1989 Accord, place ignition lock in the I position.
7. On all models, position suitable punch into hole on lock cylinder housing and depress pin, then remove lock cylinder from housing.

INSTALLATION

1. On 1989 Accord models, install ignition lock cylinder as follows:

1. Place ignition lock cylinder in the LOCK position.
2. Rotate key until it is almost at the ACC position, then insert lock cylinder until pin contacts housing.
3. Rotate key to ACC position, then push pin in and insert lock cylinder into housing until pin clicks into place.

1. On except 1989 Accord, install ignition lock cylinder as follows:

1. Place ignition lock cylinder in the O position.
2. Rotate key until it is almost at the I position, then insert lock cylinder until pin contacts housing.
3. Rotate key to I position, then push pin in and insert lock cylinder into housing until pin clicks into place.

1. Install ignition switch and connect battery ground cable.

SRS wire harness is routed near the ignition switch.

CAUTION:

• All SRS electrical wiring harnesses are covered with yellow outer insulation.
• Before disconnecting the SRS wire harness, install the short connector on the airbag.
• Replace the entire affected SRS harness assembly if it has an open circuit or damaged wiring.

IGNITION SWITCH

1. Remove the steering wheel, then remove the steering column covers.
2. Disconnect the 7-P connector from the under-dash fuse box.
3. Insert the key and turn it to "0."
4. Remove the 2 screws and replace the base of the switch.

Place key into ignition, use a paper clip and press the tiny hole on the switch. Turn the key back towards ACC position and pull the cylinder right out. Reverse procedure to install.