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Ask Chad Farhat Your Own Question
Chad Farhat
Chad Farhat, ASE Certified Technician A6 - Electrical / Electronic systems A7 Heating / Air conditioning systems
Category: Cadillac
Satisfied Customers: 1569
Experience:  Owner at Carolina Auto service & Sales , 20 years Experience in Foreign & Domestic vehicles
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Cadillac DTS Wont Crank After ECM Fuse was Accidentally

Customer Question

I accidentally pulled the ECM fuse while the 2006 Cadillac DTS was running and now it wont crank, key wont come out and gear shift wont move.
I have tried putting the ECM fuse back and removing and replacing the positive battery cable.
What can be done?
Submitted: 18 days ago.
Category: Cadillac
Expert:  Chad Farhat replied 18 days ago.

Hi, I'm Chad. Welcome to JustAnswer. I'm reviewing your question and I will be posting your reply ASAP.

Expert:  Chad Farhat replied 18 days ago.
Hey, how are you

1- You could have triggered the alarm, try the below procedure

Master reset Procedure

1- Disconnect Battery Cables ( Negative & Positive Cables )you can use any electrical wire as an extension if battery cables don't reach .

2- Hold cables Together for 60 secs ,then let go

3- Wait 15 minutes

4- Make sure all doors are closed

5- Reconnect battery Cables

6- Lock & unlock the vehicles using the key from driver door side (if you have a key fob with no blade key, just lock & unlock using the key fob buttons)
7- Enter the vehicle and attempt to start

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Customer: replied 18 days ago.
Hello, still wont crank.
The key will not come out of the ignition nor can I put the car in neutral.
Lock and unlock buttons dont work but dash is lit and radio works.
Customer: replied 18 days ago.
The key will not come out of the ignition nor can I put the car in neutral
Expert:  Chad Farhat replied 18 days ago.

1- Check all fuse with a test light, pulling the fuse should not have caused that if you installed back and it is not blown.

1- start with basic,do we have 12 volts at battery, check with voltemetr

2- is there a red security light flashing on dash

3- does the display come on at all inside the car at turn of switch ?

4- with a test light do you have 12 volts at the starter solenoid when you burn the ignition switch from on to start

5- starter relay ,did start go out and that is why you are not cranking over ?

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Customer: replied 18 days ago.
All relays seems to be good. Battery has voltage. Doors locks dont work, trunk release dont work, when I turn thr key I hear a loud single click and thats it
Expert:  Chad Farhat replied 18 days ago.

R3 relay in this diagram I sent you is your starter relay , swap it with another one like it & tell if it cranks ?

press on blue link to open up the picture of the starter relay location in underhood fuse box

Please let me know

Thank You

Chad Farhat

ASE Certified TechnicianChad

Customer: replied 18 days ago.
I've tried that already. It still doesnt start. When I turn the ignition, R4 clicks.
Expert:  Chad Farhat replied 18 days ago.

Please Rreview the system description of operation here

When the ignition switch is released from the START position, the CRANK relay opens and battery voltage is removed from the starter solenoid S terminal. Current flows from the motor contacts through both windings to the ground at the end of the hold-in winding. However, the direction of the current flow through the pull-in winding is now opposite the direction of the current flow when the winding was first energized. The magnetic fields of the pull-in and hold-in windings now oppose one another. This action of the windings, along with the help of the return spring, causes the starter drive assembly to disengage and the solenoid switch contacts to open simultaneously. As soon as the contacts open, the starter circuit is turned off. Circuit Description (Key Start) When the ignition switch is placed in the Start position a discrete 12 volts signal is supplied to the body control module (BCM) notifying it that the ignition is in the Start position. The BCM then sends a message to the engine control module (ECM) notifying it that CRANK has been requested. The ECM verifies that the transmission is in Park or Neutral. If it is, the ECM then supplies 12 volts to the control circuit of the crank relay. When this occurs battery positive voltage is supplied through the switch side of the crank relay to the S terminal of the starter solenoid.

Expert:  Chad Farhat replied 18 days ago.

R4 is ecm fuel etc , not the starter relay R3 is the starter relay

are you getting 12 volts on the crank relay side from ecm ?

Customer: replied 18 days ago.
Which one is the crank relay?
Expert:  Chad Farhat replied 18 days ago.

R3 is crank relay & also called starter relay

I sent you the diagram for it ,it will be at the end of the list in the diagram i just sent you

Expert:  Chad Farhat replied 18 days ago.

you know how to read a wiring circuit diagram ,i can send you the circuit if you want and you can follow the circuit to see why if you know how ?

let me know

Chad

Customer: replied 18 days ago.
Ive checked the R3 relay and its good. How do i reprogram the ecm or bcm. Its not a starter issue because my key will not come out and the gear shift wont move. My lovks or trunk release dont work but my radio and headlights do.
Expert:  Chad Farhat replied 18 days ago.
This your BCM location ,

Try unplugging it inspect the electrical connector with flash light ,get some electrical contact cleaner, replug and see if it reset it for you .

If not you will need a gm scanner or equivalent,because if it is the bcm or pcm you will to reprogram it to the car ,basically enter your vin # in either modules or if the key need reprogramming unfortunately

Please let me know ,i m on here next 20 minutes

Thank You

Chad Farhat

ASE Certified Technician

Customer: replied 18 days ago.
Hello, so after letting my car sit all night, i went out this morning and turned the key on and off and it came out but still doesnt crank. Im glad the key is out and my locks work now but still no crank. Any suggestions??
Expert:  Chad Farhat replied 18 days ago.
Ok now I want you to do there reset again

Master reset Procedure

1- Disconect Battery Cables ( Negative & Positive Cables )you can use any electrical wire as an extension if battery cables don't reach .

2- Hold cables Together for 60 secs ,then let go

3- Wait 15 minutes

4- Make sure all doors are closed

5- Reconnect battery Cables

6- Lock & unlock the vehicles using the key from driver door side (if you have a key fob with no blade key, just lock & unlock using the key fob buttons)
7- Enter the vehicle and attempt to start

Please let me know

Thank You

Chad Farhat

ASE Certified Technician

Expert:  Chad Farhat replied 18 days ago.
Unplugging that BCM reset the locks and the ignition switch,but now I believe our alarm is still triggered on, causing no start, meaning no power to starter

because the alarm is triggered ,not sure do the reset and let me know,& we can go from there

Please let me know

Thank You

Chad Farhat

ASE Certified Technician