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Discussion Starter #1
I'm hoping someone has run into this issue and has an answer. I have a 2002 3.8 that has a intermittent BCM issue. The car is in great shape for having 167K miles. Now that our weather is warm and requires A/C, the warning indicator starts scrolling through battery, security, and check engine. As this happens, the A/C cuts out, the BCM makes a clicking noise and chimes a couple times. When this happened last summer, I installed a new BCM but it would not program, either with the GM tool or by following the manual programming instructions. It wouldn't even start. I wasn't sure if either I got a bad BCM or maybe there was another issue with the car preventing the programming. I re installed the old unit. At least it starts and runs fine.
:gaah: Thanks in advance for any help.
 

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I'm hoping someone has run into this issue and has an answer. I have a 2002 3.8 that has a intermittent BCM issue. The car is in great shape for having 167K miles. Now that our weather is warm and requires A/C, the warning indicator starts scrolling through battery, security, and check engine. As this happens, the A/C cuts out, the BCM makes a clicking noise and chimes a couple times. When this happened last summer, I installed a new BCM but it would not program, either with the GM tool or by following the manual programming instructions. It wouldn't even start. I wasn't sure if either I got a bad BCM or maybe there was another issue with the car preventing the programming. I re installed the old unit. At least it starts and runs fine.
:gaah: Thanks in advance for any help.
A faulty ignition switch can also cause these symptoms. My 2001 did all that and more. Replacing the ignition switch fixed all the issues.
 

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Mr. Handy
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^^ Yup common problem. Many people and Dealers replace the BCM when, in fact it is the ignition switch. Also, if ignored for a while the ignition switch can take out and kill the bcm. So, have a dealer reprogram the pcm, monitor all functions of car and dash lights. If any re-appear, replace the ignition switch and possibly the lock cylinder as well.
 

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Discussion Starter #5
I had a chevy tech try with his GM tool. He was baffled too. That's why we thought it was a bad unit.
 

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Mr. Handy
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What do you mean by baffled? If he can't communicate with the BCM then, the bcm is either again fried or the ignition switch isn't supplying the voltage needed to the bcm.
 

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Mr. Handy
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Yup, such a common problem with GM ign switches it isn't even funny. Many people have complained about this problem yet, GM doesn't issue a recall for it. Sorry to say but, that's how they make their money. Without the know how or research an ign switch replacement will require a dealer. Not to mention paying a dealer to re-program the bcm if that has failed as well.
 

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8th Gen Antagonist
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Following my write-up, a chimpanzee could replace an ignition switch luckily.
 

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FIXED! Nixed the ignition switch idea, pass code works and the BCM always has ignition voltage. Replaced the BCM. Past co-worker and good friend at the Chevy Dealer sold it to me at his cost. Had another friend and current co-worker coded it with his Tech 2. So far so good.
 

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Been reading through this site and thought it was time to add my imput and questions. For a number of years I have been dealing with no start problem on 2002 Impala 3.4L. I wait for 12mins, another 12mins and sometimes another 12mins for the car to start. Dealer said a couple of different things could be the problem back many years ago but could not say 100% which one it was. Did not want to spend the money on the wrong fix and waited for the car to break. March 2012 it did, would not start and the mechanic with his tech II device determined it was the bcm because he could not communicate to it. Ordered, Cardone bcm remanu. Has worked well with a couple times last year not starting and again recently. But as of last week, the car would not start. Should have realized when the clock on the dash started to loose time and same problem many years ago. Before fix, received ignition light anti theft would come on and no start. This time no light, just won't start. The car turns over with interior lights etc come on but that is it. Decided to order ignition switch, ignition lock housing and ignition lock cylinder including keys. Thinking it is now the passlock sensor and swap it out. But after removing my ignition cylinder with key I noticed there seems to be a magnet on cylinder. Which I think would engage the passkey sensor i.e. a transfer of electrons from cylinder to passkey sensor magnet, thus receiving a voltage to pass through the 3 wires via the bcm and code for allowance of the car to start. Is my thinking incorrect?
SO MY QUESTION, WOULD IT NOT BE BETTER TO CHANGE OUT THE IGNITION LOCK CYLINDER WITH PASSKEY SENSOR, AND DO THE KEY RELEARN vs JUST CHANGING OUT THE IGNITION LOCK HOUSING WHICH IS COMPRISED OF THE PASSKEY SENSOR AND KEEPING THE ORIGINAL KEY? RockAuto web site on the product description leads me to interpret, that it’s the only problem and this will fix the problem at a low cost. Anyone on this sites have any thoughts? Received the parts today and hope for guidance on weather to change the switch and ignition lock cylinder with keys or change out the ignition lock housing which is the passkey sensor. Trying to figure out the best permutation or combination.
 

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Mr. Handy
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The passlock sensor and ign switch are common to fail. If the switch fails it can cause major damage. If you have the switch already .. replace it as well.
 

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The passlock sensor and ign switch are common to fail. If the switch fails it can cause major damage. If you have the switch already .. replace it as well.
Thank you, I have a new switch and just tried new switch with original key and slid the passkey sensor into switch and turned over with power but no start. I waited over 10mins, wait for shut down and tried again and still no start. Seeing if it may start after the 3rd shut down. Wondering if doing the 3 cycle 10mins relearn procedure for a total 30mins would do anything with the original passkey sensor? Or should I go straight to new switch and pass lock sensor key and do the 30 mins relearn procedure? Or what about the new lock housing with senor and insert original key/tumbler? My concern on using pass lock sensor key is that documentation from the box says codes will not be cleared unless I have tech II device, don't have one.
 

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Mr. Handy
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I would use your original key/cylinder for now until you get the relearn done.

Relearn procedure:

http://my.cardone.com/techdocs/pt 77-0011.pdf
Okay, original key with new switch, no start. Did it 3 times. However, did not do the exact procedure of relearn. Just let it shut after 10mins and tried to start at approx 12-15mins. Thinking I should try the new ignition lock housing with original key and do the relearn procedure. Or do the relearn on original key with new switch?
 

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Mr. Handy
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So u have a new cylinder and keys cut for it?

If so try brand new everything that u have.
 

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Yes I have both. Brand new cylinder and keys and ignition lock housing from the rockauto site, ignition lock housing is comprised of only housing and sensor.
 

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Mr. Handy
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Have u tried brand new everything?
 
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