This car has an intermittent no start condition with the security light flashing. Checked codes and found code B2960 stored. The code is for a valid but incorrect passkey signal. Now there are several different things that can cause this code but the most common is a failing passkey sensor which is part of the ignition tumbler kit. Some of the others are a faulty Ignition Switch, Body Control Computer and poor connections in the wiring harness. Because this problem is usually so intermittent there is not much real testing you can do that will result in a clear answer. I have found the only practical thing to do is to look at passkey voltage with a Tech 2 and gently wiggle the wiring some at the ignition switch and the BCM to see if there is any problem with the harness. Also look at passkey voltage while switching the key off and on. It should be about 5 volts when you initially switch the key on and then drop to a value higher than 0 and lower than 5 volts. Normally I see anywhere from .78 to 3.9 volts. If I see no other problems I always change the ignition tumbler kit and install a new ignition switch as well. If one is failing the other will not be far behind. I have seen plenty of these ignition switches fail without a passkey fault so I replace both as a rule.
With that out of the way this is the what you have to do to change the switch. Drop the tilt steering column to the full tilt down position. Remove both of the dash end caps and remove a screw from each end. Start pulling the trim panel from either end until the clips release. If it does not seem to want to release check for any extra screws that may be retaining the panel. If none are found pull harder but please be careful as panels can break.
After the trim panel is released you will have to disconnect the switches. The hazard switch needs the center tab depressed while you pull the harness connector from the switch.
The Traction control switch needs the center tab lifted slightly while the harness connector is pulled from the switch.
You will also need to remove the lower panels. There and a coulpe of retaining screws and a retaining pin or two. After all retainers are removed pull the cover towards the driver’s seat.
Disconnect the trunk release switch if present and now you will find a metal panel.
Remove the attaching screws and place aside.
Next you will need to remove the two 10mm headed screws that hold the switch assembly to the dash.
Next pull the switch down through the opening in the bottom of the dash.
With the key off release the locking tabs and pull the two main harnesses from the ignition switch. Make sure the key is off, it will save programming time.
Next turn the key on and depress the locking tab for the shifter interlock cable and pull the cable out of the switch.
Next depress the metal locking pin that hold the tumbler and sensor assembly into the ignition switch, rotate the key and pull the assembly out of the ignition switch.
Disconnect the sensor wiring harness by depressing the two side locking tabs and pull from the switch.
Install the new ignition switch and then install the new tumbler and sensor assembly.
I have another post for assembly of the tumbler kit. Please click here to see that post.
After the ignition switch and tumbler assembly are back together turn the key on and reinstall the shifter interlock cable. Then Make Sure The Key Is Off and Then Connect The Two Main Harness Connectors. Again this saves programming or relearn time. Now attempt to start the engine. Do Not be surprised if it does not start. Leave The Key ON and Wait about ten minutes or until the security light stops flashing. You may have to repeat this process up to four times in all before the system will relearn the new sensor value. The closer the new sensor value is to the original the quicker it will relearn. On some rare occasions you will have to use a Tech 2 and reprogramming software to teach the system the new value.
If it will start after the ten minute wait(sometimes repeated up to four times) and there is a passlock code for valid but incorrect value, then the most likely cause would be a faulty passlock sensor that is part of the tumbler assembly. If all of this fits your vehicle condition I would recommend replacing the sensor/tumbler assembly and the ignition switch itself. The ignition switches also have a high failure rate. Especially over 150,000 miles. I also feel the need to advise you that there are other things such as a faulty wiring harness or BCM that could cause a similar condition.
I have a 2003 Impala with the security light issue, won’t start for 10 minutes while it flashes when I try to start it. The GM dealer is looking at it but can’t get it to act up. He said his guess would be the ignition switch but if that doesn’t fix it I’m out 400$. I don’t know what the codes are, but he said there was a passlock code or something.
I understand the need to want to do something. If it were the ignition switch security sensor there would be a code stored in the BCM or PCM. Can you tell me more information about your car and the exact problem you are having?
Hey Sparky,
I don’t have any experience in car stuff or have any friends who can do the checks you suggest. I have my car at the dealer right now and he’s trying to get it to not start for 2 days. He said his guess was the ignition switch and quoted me 400+$. If he can’t get it to act up, think I should go ahead and replace the switch with the risk that it isn’t the problem?
You stated the BCM has been changed. Was it setup using a Tech 2 scan tool? A new BCM will not work until it has been setup. This can only be done using a Tech 2. Was the theft relearn performed as well? As far as disabling the system. There are gadgets that will fool the BCM into thinking everything is normal. There are several catches though. First you have to have a working system. Second the gadgets only retain the information in rom and when the battery is disconnected it has to be setup all over again. It can be done with resistors and relays but to me it is easier to just fix the problem correctly.