Codes - Where Do I Start?
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Intermediate
Joined: May 2003
Posts: 32
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From: Enfield, CT
Codes - Where Do I Start?
I have been having trouble with my keyless entry for a while, starting with poor range (all three fobs – all new batteries and retrained). Recently, I have had trouble with the driver’s door not locking and unlocking with the remote. A couple of days ago, I had trouble starting the car. When I turned the key, all the accessories came on, but the engine did not crank or make any sound at all. I locked the car with the remote, and unlocked it. The car started… (?) I found the following codes, 40-BCM B2723 PASS-Key Detection Circuit, A0-LDCM B2284 Battery#2 Fault and U1064 Loss of Communication with BCM, A1-RCDM also has U1064, B0-RFA U1016 Loss of Communication with PCM, U1064, and U1096 Loss of Communication with IPC. I cleared all codes, drove the car and got the U1064 on both door modules and B2284 on the driver door module.
Is all of this related? If so, where do I start?
Thanks in advance…..
Bob
Is all of this related? If so, where do I start?
Thanks in advance…..
Bob
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
Bob
I have seen this many times before and have even been in the same boat! You have a classic case of what sounds like a weak main 12 Volt battery. The Loss Of Communications codes give that away! As you start the car and engauge the starter motor the starter draws lot's of amps. As the amps peg high, the voltage (reserve capacity) goes low. It normaly drops to around 11.00 - 11.50 volts DC. In your case it probably is dropping into the 9's for a milli second. As the starter starts to spinn the voltage comes back up and everything work normaly. The micro processors in your car shut down around 9.5 volts. The loss of comms happens when they shut down.
Please have your battery and charging circuit ckecked out for proper operation. Make sure they LOAD test the battery.
If that checks out normally, I have a few more tricks up my sleve. I had FOB problems also and they cleared up after the main battery was changed.
Please let me know how you make out.
Bill C
I have seen this many times before and have even been in the same boat! You have a classic case of what sounds like a weak main 12 Volt battery. The Loss Of Communications codes give that away! As you start the car and engauge the starter motor the starter draws lot's of amps. As the amps peg high, the voltage (reserve capacity) goes low. It normaly drops to around 11.00 - 11.50 volts DC. In your case it probably is dropping into the 9's for a milli second. As the starter starts to spinn the voltage comes back up and everything work normaly. The micro processors in your car shut down around 9.5 volts. The loss of comms happens when they shut down.
Please have your battery and charging circuit ckecked out for proper operation. Make sure they LOAD test the battery.
If that checks out normally, I have a few more tricks up my sleve. I had FOB problems also and they cleared up after the main battery was changed.
Please let me know how you make out.
Bill C
Tech Contributor
Joined: Oct 1999
Posts: 40,995
Likes: 9,759
From: Charlotte, NC (formerly Endicott, NY)
Bill may be right about the main battery but not because of the loss of communications codes. A perfect car will get these. The modules on the bus constantly poll each other. If a noise pulse or some other interruption occurs and one module misses its poll you will get the Loss of Communications code.
Code B2723 is set when the voltage sampled at the BCM's Pass Key input circuit is high signalling that an invalid Pass Key resistance has been detected and a short to voltage or an open circuit is present. This condition must be present for 1 second. Actions taken when the code is set are:
1. The code is stored
2. A message is sent to the IPC to display a Security indicator
3. The PCM will not allow fuel to go to the engine.
4. Disables sampling of the Pass Key resistance for a time out period of 3 minutes (if this is like the C4s trying to use the key within those 3 minutes will reset the timer to max time again).
5. Does not disarm an armed UTD system
6. Steering column remains in locked position
Conditions for clearing:
1.This DTC requires an ignition cycle to go from current to history.
2. The BCM detects a valid key resistance
The following conditions may cause an intermittent:
1.An intermittent open or short to voltage in CKT 1073 or 1074.
2.Poor connections at the BCM or ignition switch connector
3.The Pass key resistor is open
4.The ignition lock key contacts or the Pass key resistor are dirty.
B2284 has to do with the battery voltage sensed at the left door control module (DCM).
To check this out you need to measure the voltage at left door control module to ground at A-C3. If the value is between 10 and 14 VDC you need to change the DCM. If the voltage is out of that range you need to check the rest of the circuit between fuse number 34 and the DCM.
The problem may not be solved by doing these things but it is a place to start. It helps to have Service Manual. It is 1400 pages of fantastic info.
Bill
Code B2723 is set when the voltage sampled at the BCM's Pass Key input circuit is high signalling that an invalid Pass Key resistance has been detected and a short to voltage or an open circuit is present. This condition must be present for 1 second. Actions taken when the code is set are:
1. The code is stored
2. A message is sent to the IPC to display a Security indicator
3. The PCM will not allow fuel to go to the engine.
4. Disables sampling of the Pass Key resistance for a time out period of 3 minutes (if this is like the C4s trying to use the key within those 3 minutes will reset the timer to max time again).
5. Does not disarm an armed UTD system
6. Steering column remains in locked position
Conditions for clearing:
1.This DTC requires an ignition cycle to go from current to history.
2. The BCM detects a valid key resistance
The following conditions may cause an intermittent:
1.An intermittent open or short to voltage in CKT 1073 or 1074.
2.Poor connections at the BCM or ignition switch connector
3.The Pass key resistor is open
4.The ignition lock key contacts or the Pass key resistor are dirty.
B2284 has to do with the battery voltage sensed at the left door control module (DCM).
To check this out you need to measure the voltage at left door control module to ground at A-C3. If the value is between 10 and 14 VDC you need to change the DCM. If the voltage is out of that range you need to check the rest of the circuit between fuse number 34 and the DCM.
The problem may not be solved by doing these things but it is a place to start. It helps to have Service Manual. It is 1400 pages of fantastic info.
Bill
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
Yea, My 98-99 series manuals are 3 volumes and weigh 20 pounds! 
The 02 set is 4 volumes and 30 pounds! 
The 05 manuals will be 10 sets and weigh 100 pounds!!!
BC
The 02 set is 4 volumes and 30 pounds! The 05 manuals will be 10 sets and weigh 100 pounds!!!
BC
