help, c5 wont start!?!
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Joined: Aug 2009
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From: Tennessee
help, c5 wont start!?!
i've read a number of threads on start up issues recently because i am experiencing a similar problem now. over the last few months, i have sporadically had times when my 2001 c5 a4 55k miles fails to start (aka the gauges do their flush and corvette flashes on the dic - just no response from the starter). this was never a recurring situation, so i just tried to keep my only key as clean as possible. however...
i recently paid for a detail job and upon my next start up noticed the security light stayed on, even while driving. this has never been part of my experiences through the failed start up process. today, i went to run an errand and am now experiencing both issues simultaneously - the car wont start nor is the security light turning off (not flashing but stays on). i've checked the codes and the only current issue is 40BCM - B2723 H C. i understand that this relates to the PASS - key detection circuit. but, i am very cloudy on what i should do from here? ive waited the allotted 3 minutes numerous times with no response. could this be related to something the detail guy did? im frustrated and out of ideas. do i need a new key? ignition switch? please help as this is my daily driver. thanks a TON!
i recently paid for a detail job and upon my next start up noticed the security light stayed on, even while driving. this has never been part of my experiences through the failed start up process. today, i went to run an errand and am now experiencing both issues simultaneously - the car wont start nor is the security light turning off (not flashing but stays on). i've checked the codes and the only current issue is 40BCM - B2723 H C. i understand that this relates to the PASS - key detection circuit. but, i am very cloudy on what i should do from here? ive waited the allotted 3 minutes numerous times with no response. could this be related to something the detail guy did? im frustrated and out of ideas. do i need a new key? ignition switch? please help as this is my daily driver. thanks a TON!
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Joined: Aug 2009
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From: Tennessee
first, thanks for your response!
ok...just tried the eraser and contact cleaner to no avail? there didnt appear to be any oxidation on the key after the spray and key removal? and to answer the spare key question....i dont. when i purchased the car from the dealer it was the only key they had. i procrastinated buying another key for no good reason. obviously, regretting that decision now. the strange thing is the car ran fine this am when i took it around the block to see if the security light was still staying on. this is so frustrating...
ok...just tried the eraser and contact cleaner to no avail? there didnt appear to be any oxidation on the key after the spray and key removal? and to answer the spare key question....i dont. when i purchased the car from the dealer it was the only key they had. i procrastinated buying another key for no good reason. obviously, regretting that decision now. the strange thing is the car ran fine this am when i took it around the block to see if the security light was still staying on. this is so frustrating...
Pro
Joined: Dec 2009
Posts: 719
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From: Columbia South Carolina
Is it your same KEY.........?
I mean how much do you trust your detailer. Is it possible he made a dupe
of your key, kept the original and now the key you have it's resister does not match, so you have a start problem?
I mean how much do you trust your detailer. Is it possible he made a dupe
of your key, kept the original and now the key you have it's resister does not match, so you have a start problem?
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From: Tennessee
i was afraid this may be the case and found that thread earlier. i'm not too mechanically inclined - at least, not enough to tear into the assembly. not yet. however, i may have some pals that could help. i guess ill continue to research and see what i can come up with. thanks for the link. anyone else have thoughts? please advise...
Tech Contributor
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
My ignition switch post does NOT address the key chip reader. Its on the FRONT of the ignition switch assembly (small silver can)
Read your KEY resistor chips with an OHM Meter. Both chips should read the same resistance. Your BCM looks for that specific resistance to allow the car to start and run. If the resistance of the key's do not match what the BCM is looking for, you see the security light and NO START.
You can purchase a precision resistor and actually wire it in to the key chip reader circuit permanently. Just put the resistor in the BCM harness side of the key chip reader plug.
BC
Read your KEY resistor chips with an OHM Meter. Both chips should read the same resistance. Your BCM looks for that specific resistance to allow the car to start and run. If the resistance of the key's do not match what the BCM is looking for, you see the security light and NO START.
You can purchase a precision resistor and actually wire it in to the key chip reader circuit permanently. Just put the resistor in the BCM harness side of the key chip reader plug.
BC
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From: Tennessee
update - car started tonight and i could, at a minimum, get it into my garage for the evening. after i let it run for a bit and turned it off, it went back to the same routine. this is puzzling to say the least. does it mean the ohm's are fine and the ignition is the issue? or does this just complicate the entire problem? 
bill, you are the man. thanks for your input. does the same advice still apply now?
bill, you are the man. thanks for your input. does the same advice still apply now?
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Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Theres a ton of reasons that could keep the car from starting. You had hard signs that the VATS was not playing. Resistance is a tricky thing. Many things can cause it to change (dirt, temperature, humidity etc....) Keep an eye on the security light when it acts up and that will be a clue.
The connections at the starter are another thing to check. Clean and tight is the cure for that issue;
The starter solenoid is a VERY COMMON failure point.
Heres a circuit for you. It will allow you to see the LOW VOLTAGE - LOW CURRENT side of the circuit and the LOW VOLTAGE - HIGH CURRENT. As "SebringSixSpeed" stated,,the TDR is the dividing point for those two sides of the circuit. Its an important troubleshooting point that allows you to break into the circuit and see whats happening.
BC
The connections at the starter are another thing to check. Clean and tight is the cure for that issue;
The starter solenoid is a VERY COMMON failure point.
Heres a circuit for you. It will allow you to see the LOW VOLTAGE - LOW CURRENT side of the circuit and the LOW VOLTAGE - HIGH CURRENT. As "SebringSixSpeed" stated,,the TDR is the dividing point for those two sides of the circuit. Its an important troubleshooting point that allows you to break into the circuit and see whats happening.
BC
Melting Slicks
Joined: Jan 2002
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From: Nokomis FL
PS, I could start mine once I wiggled the wire but it got worse and worse until I change the starter.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
When I had my 02 ZO6 NO START ISSUE,,,I did the following to help narrow down the issue. Turn the key to CRANK and hold it there,,,Pump the clutch up and down on and off of the clutch safety switch. If the SECONDARY LOW VOLTAGE side is working properly, you chould hear the TDR click on and off as you pump the clutch on and off the switch.
Hold the key to CRANK and have some one TAP on the starter solenoid. If you tap the solenoid and it starts,,,thats most likely the issue. I kept a long piece of insulated rebar in the trunk for those special NO START times.
I would snake the "INSULATED" rod down beteween the header pipes and whack the solenoid.
If you dont use an insulated rod, your new nick name may be sparkey if you miss and hit the electrical connection. Oh, and you will also need to repair that header pipe. 
Bill
Hold the key to CRANK and have some one TAP on the starter solenoid. If you tap the solenoid and it starts,,,thats most likely the issue. I kept a long piece of insulated rebar in the trunk for those special NO START times.
I would snake the "INSULATED" rod down beteween the header pipes and whack the solenoid.
If you dont use an insulated rod, your new nick name may be sparkey if you miss and hit the electrical connection. Oh, and you will also need to repair that header pipe. Bill
Last edited by Bill Curlee; Feb 21, 2010 at 10:57 AM.
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From: Tennessee
update again - just had my wife steer while i pushed it out into the driveway to get some working room. she noticed as she turned the system back off the message "charge system fault" flashed on the display???? my gauges show the battery hoovering around 11.9 volts. new clue or just another one that leads us to the same conclusions?
Tech Contributor
Joined: Dec 2006
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From: Van Buren Arkansas
Wounded Warrior Escort '11
Low battery volts will cause you all sorts of problems. Verify your battery with a load test and check all the connections at the battery itself, solenoid as Bill showed the great pictures of. You need at least 12.5 vdc across the battery when the car is off for the computers to work.
Tech Contributor
Joined: Dec 1999
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Start by removing the battery. Charge it FULLY with a Charger. Then go have it fully tested for CCA and Reserve Capacity. While its OUT,,clean the battery cable terminal ends. Scrub them with a wire brush and flush out the terminals with brake parts cleaner. Inspect the crimped terminals under the rubber boots for damage/corrosion.
CHECK THAT STARTER SOLENOID CONNECTION!!!!
When you reinstall the battery,,,TORQUE the batter terminal bolts to 11 ft/lbs for proper connection.
Check the BATT terminal on the back of the alternator (under the black boot) for proper connection. Make sure that its not loose, burnt or damaged.
That the next step.
BC
CHECK THAT STARTER SOLENOID CONNECTION!!!!
When you reinstall the battery,,,TORQUE the batter terminal bolts to 11 ft/lbs for proper connection.
Check the BATT terminal on the back of the alternator (under the black boot) for proper connection. Make sure that its not loose, burnt or damaged.
That the next step.
BC
