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Ask Dave Nova Your Own Question
Dave Nova
Dave Nova, Buick Technician
Category: Buick
Satisfied Customers: 19450
Experience:  ASE Master Certification. GM World Class Certification
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2000 lesabre, security light and sound comes on as you

Customer Question

2000 lesabre, security light and sound comes on as you drive. On and off also radio does not play as it does this. What is going on
Submitted: 11 months ago.
Category: Buick
Expert:  Dave Nova replied 11 months ago.

When this occurs, do the power windows still work?

Customer: replied 11 months ago.
Customer: replied 11 months ago.
Still no answer but it appears I have been charged
Expert:  Dave Nova replied 11 months ago.

Sorry for the delayed response. This source of your problem may be in the ignition switch, body control module, or the wiring. Best place to start would be to check voltage on the White wire coming off the ignition switch. If the voltage drops while the problem is occurring, replace the ignition switch. If the voltage is okay, check the wiring for any possible shorts or chafing. If wiring is okay then the body control module would be suspect.

Because the problem is affecting the dash integration module (for radio turn on signal) and the theft deterrent module, I am leaning towards ignition switch failure.

Customer: replied 11 months ago.
Not the bcm I changed it radio says loc, so I am changing it back. If you remove power it is fixed for about 15 mins and then comes back.
Expert:  Dave Nova replied 11 months ago.

Are you removing power by cycling the key off?

Customer: replied 11 months ago.
Disconnecting the battery
Expert:  Dave Nova replied 11 months ago.

Which BCM did you replace? Was it the dash integration module?

Customer: replied 11 months ago.
The one under the dash glovebox
Expert:  Dave Nova replied 11 months ago.

Do you have access to a scan tool?

Customer: replied 11 months ago.
Expert:  Dave Nova replied 11 months ago.

Are there any diagnostic trouble codes stored? Do any of the modules not respond when the problem is occurring?

Customer: replied 11 months ago.
I will get the codes and send to you tomorrow
Expert:  Dave Nova replied 11 months ago.

Thanks.

Customer: replied 11 months ago.
P0300,p0463,p0507,p1381,p1602,p1626,p1811. There's a lot
Expert:  Dave Nova replied 11 months ago.

Two of these codes (P1381 and P1602) specifically deal with loss of serial data communications between the PCM (engine control computer) and the EBCM (abs brake control computer). Check the wiring first, the serial data wire is Purple. If the wiring looks okay, try disconnecting the electrical connectors at the EBCM and driving the vehicle (Note: ABS warning light will stay on) If the original problem does not surface with the EBCM disconnected then the problem is a short in the EBCM that is shorting out the serial data line and shutting down the radio and theft deterrent modules.