My Car: 2001 Coupe, 35K miles no mods, automatic trans
Problem: The alarm goes off randomly. Not an everyday occurence, but frequently enough for me to want the problem fixed.
Seems to be mostly associated with the drivers door not locking when I arm the system. The alarm goes off when I open the door. I can silence it only by starting the car. Pressing the key fob alarm or unlock buttons does not work, nor does using the key in the door lock.
A couple of times the alarm has gone off its accord, but I did have the keys in my hand, so perhaps I accidently hit the panic button.
Once the alarm went off in the driveway and the keys were just laying in my office.
A few days ago the door locks would not lock automatically when I engaged Drive, but would unlock in Park. No alarm problems since I have pulled the horn fuse! I then took the car into the local Chevy dealer and an independent shop, but they could not diagnose the cause of the problem, since the door locks and alarm started working perfectly.
I am not showing any codes.
Solution: I would appreciate guidance from this group.
Searching the previous posts on this problem it seems like there are two most likely causes.
1. Lock actuator
2. Interface module lock control
Thanks,
David Argent
Hilton Head Island
SC

 

Always pull your dash DIC codes.


Mr. Sam

 

 

Sorry, what I meant was nothing came up on the DIC. I just pulled the codes and got
BO-RFA 2 codes. U100H and U1064. I get these ocassionally.

Thanks,
David

 

I wonder if you disabled the auto lock feature through the dic if that would stop it from happening. It may be something impossible to trace down for a while but disabling the auto lock feature might give you some comfort and lack of irritation. May not help either. Personally, don't know much but am intrigued about all the little issue with a C5.

Pops....

 

Have temporarily pulled the horn fuse, Will keep you all posted once I figure out how to proceed

 

Correction Should read U1000H and U1064

 

Is the horn going off by itself or is it the alarm? Set the DIC so the horn and lights will flash when an alarm goes off.

It is not uncommon for the steering horn membrane to activate the horn. That is not an alarm.


Mr. Sam

 

When the horn goes off, does it just blow. or does it BEEP, BEEP BEEP?

Bill

 

It goes Beep Beep Beep

 

Recommend getting the lock feature set up in the DIC so you can see if that was the problem with the door locking when you drive off.

Report back results.

BC

 

Here is an update Bill - with a correction.
Pulled the horn fuse a couple of days ago because of the alarm going off randomly
Lock and arm is set to lights only and is working. I have always used this setting
The locks are now working fine with both the fob and the Drive lock and Park engine off unlock features
The alarm is set to Horn and Lights
Deliberate triggering of the alarm with the fob or reaching through the window and manually unlocking the door now does nothing. Assume pulling the horn fuse has also disabled the flashing light feature.
Codes U1000H and 1064H under BO-RFA are back again this am. I cleared them and will check again next time I drive the car and before I switch the engine off.
Just ran an errand and no codes when back home, parked and engine running.

Thanks,
David

 

The door lock issue may be your relays in your door control module. I know I had similar symptoms where I'd lock the car but the passenger door wouldn't lock, then when I open the door the alarm goes off. That would also account for why your doors don't lock but do unlock when put in drive.

There may be other issues as well but it sounds like the DCM relays may be intermittently working. I will let the electrical guru's advise if this may be part of the solution. Although the fact that your symptoms seem to have disappeared when you removed the horn fuse may make my above statement null.

 

Appreciate the reply. Can you tell me where you got the replacement DCM from? And the cost? I would be interested to know how you decided it was the DCM at fault. Through the symptoms, or some electronic test?

 

Wait until Bill/Dadaroo respond that that's what they think the problem is just so you're not doing unnecessary work. I bought them from Digikey. They're $1.72 a piece and you'll need two per board depending if you replace your lock and unlock relays. I only replaced my lock relay I believe but bought extra's just in case I have problems in the future.

JSM1-12V-5

Here's a video showing what you'll need to do.