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Does New BCM have to be Flashed by the Dealer?
08-01-2019, 08:38 AM
#61
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I was driving to town and noticed that my door locks wouldn't work by remote or door switch. And I could constantly hear a clicking noise coming from the bcm. I checked to make sure and could feel the bcm clicking. Now the car won't start or anything and the gauges act goofy
08-01-2019, 10:08 AM
#62
The door locks problem could be caused by the BCM or the BCM could be clicking because of the locks (stuck input). The starting problem is not the BCM unless the SECURITY light is on (or flashing) in the instrument cluster. The gauges aren't related to the BCM at all.
Check the red/black and orange/black wires in the green 6-pin connector at the BCM. Those are the door lock trigger wires (lock and unliock respectively). It sounds like one or the other may be shorted to ground. They are grounding trigger wires anyway so no fuses would blow but a constant ground would cause the BCM to cycle, creating that clicking noise from the relays.
Check the red/black and orange/black wires in the green 6-pin connector at the BCM. Those are the door lock trigger wires (lock and unliock respectively). It sounds like one or the other may be shorted to ground. They are grounding trigger wires anyway so no fuses would blow but a constant ground would cause the BCM to cycle, creating that clicking noise from the relays.
08-01-2019, 10:22 AM
#63
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The security light does come on and flash. Where would those wire ground out to because I've looked thru all the wiring and can't find anything. That's why I was leading towards it being grounded out in the bcm or something
08-01-2019, 10:33 AM
#64
The flashing SECURITY light means the VATS in the BCM can't see a resister pellet in the ignition key (i.e. open circuit). It would be on solid if it could see a resistance but it didn't match the programmed value. There are many ways the circuit could be open... a break in the wires, the orange connector under the steering column unplugged, bad contacts inside the ignition cylinder, or a damaged key. Depending on the cause, you can either fix it or just do a VATS bypass.
The door lock inputs ground at G200 - the ground stud behind the left kick panel. But the problem here would not be a bad ground but rather too much ground... one of the wires having damaged insulation and grounding out against something metal under the dash or inside the door. It's easy to test - unplug the green plug and check continuity to ground on those two wires. You should only see ground when the lock switches are engaged, otherwise there should be no continuity.
The door lock inputs ground at G200 - the ground stud behind the left kick panel. But the problem here would not be a bad ground but rather too much ground... one of the wires having damaged insulation and grounding out against something metal under the dash or inside the door. It's easy to test - unplug the green plug and check continuity to ground on those two wires. You should only see ground when the lock switches are engaged, otherwise there should be no continuity.
08-01-2019, 10:41 AM
#65
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Ok I'll check it out with my meter. And I have already done the bypass with the resistors. I've been driving the car for almost 3 years without issue since the bypass and all of a sudden this happened.
08-01-2019, 10:50 AM
#67
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They were loose. I messed with them and the car started. But the bcm constantly continued to click. I went ahead and soldered the resistors connections so I know that's not an issue anymore.
08-05-2019, 10:47 AM
#69
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How to I get to the orange wire under the steering column to check if it is plugged in? My Security Light has been on Steady for years but my keys have been checked and match the programmed value.
08-05-2019, 11:54 AM
#70
It's not an orange wire... it's two white wires in an orange sheath under the steering column.
You're lucky. When the BCM finds a VATS resistor issue while the engine is already running, it considers it a system fault rather than a theft attempt and will allow the car to be started despite the fault. If it discovers the resistance mismatch while starting the car, it will prevent the car from starting until the correct resistance is seen. That's why you've been able to start the car even with the obvious error indicated by the security light. Still, it's not something to be ignored - the system has been known to reset when the battery is disconnected (for battery replacement or other electrical work) and treat future resistor mismatches as theft attempts and block starting the car.
You're lucky. When the BCM finds a VATS resistor issue while the engine is already running, it considers it a system fault rather than a theft attempt and will allow the car to be started despite the fault. If it discovers the resistance mismatch while starting the car, it will prevent the car from starting until the correct resistance is seen. That's why you've been able to start the car even with the obvious error indicated by the security light. Still, it's not something to be ignored - the system has been known to reset when the battery is disconnected (for battery replacement or other electrical work) and treat future resistor mismatches as theft attempts and block starting the car.
08-05-2019, 01:18 PM
#73
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And how would it detect a mismatched resistor when the resistors in my Original keys are the original? If it accepts them now. it should accept them always? I think there is a loose wire or something else that has caused the Security light to stay on for 4-5 years now.
08-05-2019, 01:19 PM
#74
Sorry... I don't understand the question. You get to the wires by climbing under the dash on the driver's side and looking up at the steering column to see a small harness with orange insulation (sheath) with two white wires in it. There is also an inline connector attached to those two wires which you can unplug and use as a point of testing or as a place to install bypass resistors.
08-05-2019, 01:22 PM
#76
Often the change in resistance is caused by grime on the key pellet or the contacts inside the ignition cylinder. Also, corrosion on those contacts in the cylinder can cause an inaccurate resistance reading. Or the wires to the contacts in the cylinder could be damaged.
08-05-2019, 01:25 PM
#77
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Do I need to remove anything to see the harness? If it is loose and I unplug it and plug it back in any repercussions?
Last edited by skat4160; 08-05-2019 at 01:41 PM.
08-06-2019, 08:48 AM
#78
No, the wires will be visible without removing any dash or trim pieces. Nothing untoward will happen if you unplug the connector. The two wires are simply part of a closed loop between the BCM and the contacts in the ignition cylinder to measure the key pellet resistance when the key is inserted.
08-07-2019, 05:42 PM
#79
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I looked this morning and no wires are visible. There is a panel that has screws in it and another panel all the way down to the gas and brake pedal. What am I missing?