6pac

The security light comes on the instrument gauge cluster for no "good" reason when I am driving. If I turn the car off and then on it goes away. 1998 coupe. Happened last night and then this morning. I just got the column lock recall done so I don't know if it is related.

tstar

Could be a couple of things…. Here’s a little run down of the security systems in the C5:

The C5 has two antitheft systems :
One is the Content Antitheft, the second is the Vehicle Antitheft. The security light stays on after the car is started if there is a problem with the Vehicle Anti -Theft system. The security light tells you the status of the Content Antitheft system (Horn alarm) when the key is off. If the Key is on, or engine running, the Security light is the status of the Vehicle Antitheft system (VATS, Starter cut-off, fuel cut-off). The light will stay on if there is a fail-safe fault with the VATS or Fuel cut-off. Based on the VATs system of the BCM, that enables the starter and sends a coded data-word to the PCM to enable fuel.

Have you checked your codes? If not check them and post them here. It might help to clear all the old codes and start the car and try and drive it to set new codes. Before you shut the engine off write down all your codes and note any “C” codes especially.

One of the 1st things to try is cleaning the resistor pellet imbedded in your key with rubbing alcohol just to make sure.

It really sounds like your BCM could be bad or needs re-programmed:
1) Your ignition key has a pellet in it that has a set resistance. Your current BCM looks for that resistance level and uses that to determine if the key you inserted is valid.
2) If the resistance is correct the BCM sends a "password" to the PCM that tells the PCM it is OK for the car to be driven. This "password" is changed every time the BCM and PCM communicate. Replacing the BCM requires that the BCM and PCM password are re-synchronized.
3) The BCM needs to know what options are installed in your car. For example, if you have the RTD (Real Time Damping) suspension installed, the new BCM needs to know this option is installed on the car.

All of these issues are fixable if you have a Tech2 device or it needs to be done at the dealership.

6pac

I get the following codes: TCS C1221H & C1222H "LF/RF wheel speed sensor imput signal is 0". B2723H "Pass-key detection circuit". LDCM B2282H & B2284H " Battery circuit #1 & #2. U1064H "loss of commubications with BCM

I cleared the codes and I will drive it tomorrow to see if any thing pops up. Thanks

Alfcarguy

tstar

OK good job, well your pass key is what you're concerned with here. You need to get that C1221 looked at too!

Alfcarguy - What the hel* is that? "Mitchel on demand system"?????

Alfcarguy

Okay I thought I was going to send you other stuff but reading it its saying with a Scan Tool do this blah blah blah, if you want to do it your you might be getting into back probing the BCM module to make sure its giving you the right readings, cause I say you don't need no Scan tool when you can back probe to get the same readings a Scan tool will tell you.
But first do the test that I have posted and if you want to do some hands on testing than I can post up what the readings for the Body control module are, you will need a test light and probably a DVOM
Digital volt ohm meter thats. But let me know. You might find your BCM ( body control module ) and unhook it make sure to unhook negavative cable and look at the pins make sure there not corroded and that all is making good connection. The BCM is located Mounted on the toe board in right foot well Let us know what you come up with and how you want to go about this. If you want to leave it up to a pro or you want to continue.

Alfcarguy

Tstar yep its all I have for right now, but I can't complain when it was free. I wanted something for the wire diagrams, I am maybe working on getting a copy of Alldata. Not that I really cared for Alldata or Mitchell but if it gets the job gone thats all that really matters.

Alfcarguy

And I wasn't wanting to touch on the codes until I know there Hard code's and not soft codes ( false codes ) so until you do what I PM you about than I wont really go there. First things first. Than we will move on. Hope this helps.

tstar

Thanx for the vote of confidence! Helped a guy out in another forum with the same code and I thought it would be his key... ended up needing a BCM.... so ya never know

6pac

ok. I cleared all codes last night. I drove it today and after a few cycles I get the B2723H "Pass-key detection circuit code again. I go to the store to change the keychain FOB batteries and then to program the key Fob transmitters. One of them isn't read by the system (maybe the transmitter is bad. Now the one that did program is locking and unlocking the doors when I get close to the car BUT PASSIVE IS OFF on the key chain.

As of now the car does not seem to be unlocking or locking the doors automatically when passive is off.

The BCM must be going. I looked at it but it seemed alright (no obvious corrosion) I took the battery out and no corrosion underneath. Who knows.

tstar

Heck no! if it's free then that's great!

tstar

The B2734 had nothing to do with the RFA function of the key fobs, although that should be a fun one to fix. First things first.

Have you tried cleaning your resistor pellets in your key with rubbing alcohol?

It sounded like you were checking your PCM not the BCM, as Alfcarguy said... the BCM is in the passenger footwell under a carpeted panel. It too is subject to damage from water mainly due to a plugged drain line in the AC. If you see evidence of water in that area you'll have to clear the AC drain line too. Take off the connector and check the pins too…

This code indicates a short or open in the circuit. The PASS Key wires going into the BCM are white/black pin A3 and purple/white pin B2 and they run to the ignition switch pins B and A respectively. You should ohm them out .

Here’s the repair procedure per my manual;
· The following conditions may cause an intermittent malfunction:
o There is an intermittent open or short to voltage in CKT 1073 or CKT 1074.
o There are poor connections at the BCM or the ignition switch connector.
o The PASS-Key® resistor is open.
o The ignition lock cylinder key contacts or the PASS-Key® resistor is dirty or loose.
· If the key resistor pellet is incorrect, there will be no BCM outputs to the theft deterrent relay or to the PCM. This state will last about 3 minutes. If a key is inserted, or the ignition is turned ON again before the 3 minute time frame is complete, the timer will reset to 3 minutes. Disconnecting the battery will not clear the timer sequence, but the timer will reset to 3 minutes when the battery power is restored. Even if a proper key is inserted during one of the time periods, the vehicle will not start until the total time period has lapsed.
· Clean away any dirt or grease from the key resistor. The foreign substances could interfere with the key detection circuit and set a DTC.
· If there is an open or a short to voltage on CKT 1073 or CKT 1074, the vehicle will exhibit a no crank condition.
Check for any poor connections at the BCM and at the ignition lock cylinder. A poor connection can cause an open, a short, incorrect PASS-Key® resistance, or an intermittent malfunction. If the DTC is a history DTC, the problem may be intermittent. Perform the tests while moving the related wiring, the connectors, and the key. This can often cause the malfunction to appear.

If you can’t find anything obvious, I’d take it in and the have the techs run the diagnostics on the Circuit. It could be your ignition switch too.

6pac

I will probably take it in. I did clean the pellets with rubbing alcohol and I checked both the PCM & BCM for obvious corrosion (none found).