Start Problems with 98 C5 127,000 mi
Thread Starter
Heel & Toe
Joined: Mar 2011
Posts: 20
Likes: 0
From: Highlands Ranch CO
Start Problems with 98 C5 127,000 mi
I have read all the postings on the start problems and thank you for all the information.
My problem after changing the starter, Anti theft deterrant relay, checking all the wiring and running through all the learn tests on the key pass is it seems like the BCM forgets, or when it goes to sleep it doesn't wake up with the entry of the key. If I wait 3min the starter engages but no fuel, if I wait for 10 more sec then it starts sometimes with security light on all the time and sometimes it is out. Very frustrated after trying all tthe postings and help but still have problems.
Thanks
My problem after changing the starter, Anti theft deterrant relay, checking all the wiring and running through all the learn tests on the key pass is it seems like the BCM forgets, or when it goes to sleep it doesn't wake up with the entry of the key. If I wait 3min the starter engages but no fuel, if I wait for 10 more sec then it starts sometimes with security light on all the time and sometimes it is out. Very frustrated after trying all tthe postings and help but still have problems.
Thanks
Tech Contributor
Joined: Jan 2007
Posts: 19,472
Likes: 1,171
From: Dyer, IN
I have read all the postings on the start problems and thank you for all the information.
My problem after changing the starter, Anti theft deterrant relay, checking all the wiring and running through all the learn tests on the key pass is it seems like the BCM forgets, or when it goes to sleep it doesn't wake up with the entry of the key. If I wait 3min the starter engages but no fuel, if I wait for 10 more sec then it starts sometimes with security light on all the time and sometimes it is out. Very frustrated after trying all tthe postings and help but still have problems.
Thanks
My problem after changing the starter, Anti theft deterrant relay, checking all the wiring and running through all the learn tests on the key pass is it seems like the BCM forgets, or when it goes to sleep it doesn't wake up with the entry of the key. If I wait 3min the starter engages but no fuel, if I wait for 10 more sec then it starts sometimes with security light on all the time and sometimes it is out. Very frustrated after trying all tthe postings and help but still have problems.
Thanks
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
An absolute fix would be to have your local tuner or get a mail order tuner to TURN OFF the theft system---
However be aware that you won't have any theft device which isn't a big deal anyway to me--
Trying to track down a VATS system error can be expensive (labor wise)--with no gaurantees of ever finding a solution--
The fuel shutting off is from the VATS-- If you want to try and track down the cause--look for bad grounds or try using another key for the same vehicle--
However be aware that you won't have any theft device which isn't a big deal anyway to me--
Trying to track down a VATS system error can be expensive (labor wise)--with no gaurantees of ever finding a solution--
The fuel shutting off is from the VATS-- If you want to try and track down the cause--look for bad grounds or try using another key for the same vehicle--
Thread Starter
Heel & Toe
Joined: Mar 2011
Posts: 20
Likes: 0
From: Highlands Ranch CO
Mystery codes are;
P1631
B2721
but not all the time. I have cleaned all ground points per previous posting. Car ia starting now but I have to wait the 3min and 10 sec sometimes and security light is also on sometimes but not always. Thanks
P1631
B2721
but not all the time. I have cleaned all ground points per previous posting. Car ia starting now but I have to wait the 3min and 10 sec sometimes and security light is also on sometimes but not always. Thanks
Thread Starter
Heel & Toe
Joined: Mar 2011
Posts: 20
Likes: 0
From: Highlands Ranch CO
Thanks, tried using another key but nothing changes. cleaned all the grounds including the two wires above the starter.still faulting the pass key but not all the time. Thanks
Tech Contributor
Joined: Jan 2007
Posts: 19,472
Likes: 1,171
From: Dyer, IN
Most likely a bad lock cylinder. You can verify everything with a meter, before ordering the part.
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Tech Contributor
Joined: Jan 2007
Posts: 19,472
Likes: 1,171
From: Dyer, IN
I have not read over Bills ignition switch completely, but I'm fairly certain, that it is for the repair of the ignition switch.....not the lock cylinder.
Last edited by lucky131969; Jun 15, 2011 at 01:37 PM.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
If your having a VATS issue, you are having an issue with the KEY SENSOR on "FRONT" of the ignition switch. The silver can has fingers inside the can that contact the resistor pellet in the key. That key chip resistance is read by the BCM and MUST MATCH the value inside the BCMIf the sensor or the key chip is dirty, the incorrect resistance will be read. You can read the resistance of the resistor pellet on the key with an OHM METER and write down that value.
Disconnect the Key Sensor from the harness, insert the key inside the ignition switch and read the resistance value on the pig tail off the sensor. Those resistance values should match or be very very close to matching!!!
If ther way different, you have issues with the sensor.
Heres a picture of the sensor and the pigtail on the end of the ignition switch!
Thread Starter
Heel & Toe
Joined: Mar 2011
Posts: 20
Likes: 0
From: Highlands Ranch CO
Thanks you are correct. I'm going to read the resistance on the pig tail from the VATS key reader on the front of the ignition tumbler and see if it is the same as the key. Thanks for your input it is really appreciated.
Thread Starter
Heel & Toe
Joined: Mar 2011
Posts: 20
Likes: 0
From: Highlands Ranch CO
Thanks Bill your postings are really helpful. I will read all the resistance on Ignition reader and lock tonight. I feel I'm actually getting closer to the fix, or some light at the end of the tunnel. Thanks again
Advanced
Joined: Oct 2010
Posts: 71
Likes: 0
From: Jonesboro, AR
Just for the fun of it measure your pellet today and swing by radio shack. For as little as two dollars you could figure out tonight while its apart if the bcm is even reading the resistance by plugging the resistor/s into the vats connector.
Tech Contributor
Joined: Jan 2007
Posts: 19,472
Likes: 1,171
From: Dyer, IN
......or for no cost at all, you can just take a resistance measurement, as previously suggested by Bill.
Advanced
Joined: Oct 2010
Posts: 71
Likes: 0
From: Jonesboro, AR
I'm not trying to override what Bill suggested I've read a many of his great posts..but even after cleaning it if it did ever fail to work again he could use the resistor until he could get a new switch in. For having to do all the disassembling to get to the connector, $2 worth of resistor would be worth the instant gratification that it would start up with no problems even before cleaning the switch.
Burning Brakes
Joined: Aug 2010
Posts: 930
Likes: 13
From: Aiken SC
If your having a VATS issue, you are having an issue with the KEY SENSOR on "FRONT" of the ignition switch. The silver can has fingers inside the can that contact the resistor pellet in the key. That key chip resistance is read by the BCM and MUST MATCH the value inside the BCMIf the sensor or the key chip is dirty, the incorrect resistance will be read. You can read the resistance of the resistor pellet on the key with an OHM METER and write down that value.
Disconnect the Key Sensor from the harness, insert the key inside the ignition switch and read the resistance value on the pig tail off the sensor. Those resistance values should match or be very very close to matching!!!
If ther way different, you have issues with the sensor.
Heres a picture of the sensor and the pigtail on the end of the ignition switch!
tracer1
Tech Contributor
Joined: Jan 2007
Posts: 19,472
Likes: 1,171
From: Dyer, IN
I'm not trying to override what Bill suggested I've read a many of his great posts..but even after cleaning it if it did ever fail to work again he could use the resistor until he could get a new switch in. For having to do all the disassembling to get to the connector, $2 worth of resistor would be worth the instant gratification that it would start up with no problems even before cleaning the switch.
Burning Brakes
Joined: Aug 2010
Posts: 930
Likes: 13
From: Aiken SC
tracer1
Thread Starter
Heel & Toe
Joined: Mar 2011
Posts: 20
Likes: 0
From: Highlands Ranch CO
Lucky and Bill, Thanks for all your help and everyone else that answered my posting. I found a LOOSE pin on the key reader connector as per Bill's suggestion. Everytime I put the key in it the resistance was different and the BCM was having a problem deciding which resistance to use. After fixing connector I have 10 successful starts and 0 codes and no pull key issues. I believe we have a good fix. Thanks everyone for your help.
Don8585
Don8585
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
FANTASTIC! Thank You for posting the result and deficiency! It helps a lot of other people understand the issue and fix their own problems in the future!
Bill
Bill
