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Ask GM Tech (Cam) Your Own Question
GM Tech (Cam)
GM Tech (Cam), Chevy Technician
Category: Chevy
Satisfied Customers: 29427
Experience:  GM Grand Master Technician 2007. 14 years experience.
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I have a 1999 blazer s10 with the following problem. few

Customer Question

Hi, I have a 1999 blazer s10 with the following problem. For a few days now pressing the fob button to unlock the doors and the immobilizer will not work. If I press the open button on the fob , the door locks cycle closed and open again, but immobilizer is still blocking. Pressing again the unlock on the fob sometimes only opens the driver side door and the car will start. Closing the doors with fob button same problem. Door locks cycle close and open. Rear hatch release button on the fob doesn't do anything. Reprogramming also doesnt work ie hold down open door switch , cyle ignition on and off twice etc
It looks like it woud be stuck in programming mode but pressing both open and close buttons on the fob simultaniously also has no effect. Any idea what else to do ? tks Peter
Submitted: 1 year ago.
Category: Chevy
Expert:  GM Tech (Cam) replied 1 year ago.

Hi Peter, I am Cam.

Is this the factory system or an aftermarket one?

Customer: replied 1 year ago.
This is the factory system
Expert:  GM Tech (Cam) replied 1 year ago.

Lets try a reset.

Take the battery cables off the battery, hold the ends together for 10 seconds then attach them to the battery and see what happens. This will reset the whole vehicle.
If you have 2 batteries, then remove both and touch only one set.

See if this changes anything.

Customer: replied 1 year ago.
Tks Cam ,
done it. The door locks still cycle up and down for pressing the fob once.Security light illuminates for a few seconds when turning the ignition to on and then goes out. So engine start should be enabled.
Expert:  GM Tech (Cam) replied 1 year ago.

Ok, this would indicate to me that the Body Control Module (BCM) may have failed then. IF the locks cycle and the system does not disable that’s usually a module issue.

Customer: replied 1 year ago.
BTW I have a GM tech II if that helps but I havent used it a lot yet.
Expert:  GM Tech (Cam) replied 1 year ago.

Does it show any body codes?

Does the engine start and run?

Customer: replied 1 year ago.
no dtcs
but now fob is dead
Expert:  GM Tech (Cam) replied 1 year ago.

OK, does the engine start and run, meaning has this disabled the engine starting and the pass lock system?

Customer: replied 1 year ago.
engine doesnt run and security light is on
Expert:  GM Tech (Cam) replied 1 year ago.

OK, have you tried the pass lock relearn?

Turn the key on and attempt to start the car, It may crank, it may start and stall or it may do nothing at all, this is fine, still cycle the key to start then release the key back to run.
Wait 10 minutes with the key in run. The passlock light should be flashing and the DIC will say "Service Vehicle" or "Security" or have a picture of a car with a lock during that 10 minute span.
After 10 minutes has passed, turn off the car, count to 10, and try to start it again and release the key back to run.
Wait another 10 minutes.
After 10 minutes, turn car off 10 seconds and try to start again and release the key to run.
Wait another 10 minutes.
After 10 minutes, turn car off 10 seconds and try to start again.
It should start up this time. The passlock has been learned.

During this process, turn the fans off, radio off and cycle the headlights off so the battery will not go dead. If needed, use a battery charger.

Customer: replied 1 year ago.
you mean leave the key in the ignition "on" position ?
Expert:  GM Tech (Cam) replied 1 year ago.

Yes, once it stalls, leave it in the ON position for the time.

Customer: replied 1 year ago.
now the security light is on steady and battery light on. so in 10 min. it shoud be flashing ?
Expert:  GM Tech (Cam) replied 1 year ago.

It should flash but may not. Proceed all the same and see what that does.

Customer: replied 1 year ago.
start no.1, BTW security light didnt flash
waiting another 10 min now
Expert:  GM Tech (Cam) replied 1 year ago.

ok

Customer: replied 1 year ago.
next start done
Expert:  GM Tech (Cam) replied 1 year ago.

ok

Customer: replied 1 year ago.
actually I was thinking to use the code override function in the tech II. Would this have the same effect as this exercise ?
Expert:  GM Tech (Cam) replied 1 year ago.

NO, the only way to do this is the 30 min procedure or with a programming which takes 10 mins. The programming needs the GM programming server.

Customer: replied 1 year ago.
ok
Expert:  GM Tech (Cam) replied 1 year ago.

ok

Customer: replied 1 year ago.
final 10 min started
Expert:  GM Tech (Cam) replied 1 year ago.

ok

Customer: replied 1 year ago.
engine didnt start
Expert:  GM Tech (Cam) replied 1 year ago.

OK, so I think your Bcm is faulty. Can you show the data display from the BCM?

Customer: replied 1 year ago.
you mean on the tech II ?
Expert:  GM Tech (Cam) replied 1 year ago.

Yes, data display from the Tech 2.

Customer: replied 1 year ago.
got it
Expert:  GM Tech (Cam) replied 1 year ago.

ok

Expert:  GM Tech (Cam) replied 1 year ago.

While your getting that, I am heading to the hardware store for a bit. Beback in 15-20.