03 LB7 security light
- Thread starter lutzjk913
- Start date
Not sure if you've figured it out yet or not, but I just remembered had a scenario with security light on in the cluster, but the truck started and ran fine.
Earlier this year after a round of troubleshooting, I had Efilive flashed my ECM back to what I thought was my stock tune and ended up with a no-start condition and security light on. Suspecting my original tune file had been corrupt somehow, I figured it would be best to just start with a clean slate. So I sent off my ECM to SoCal Diesel to have it flashed back to a clean stock tune, with the vehicle security stuff turned off. When I got it back the truck started and ran fine but the security light stayed on in the cluster. Scanning with my CTS2 and with my Efilive Autocal showed no codes. Lorenzo@SoCal had me send the ECM back to him where he did some repair work on it beyond just a simple reflash. When I got it back, no more security light.
In my case it seemed that something in the ECM died or got corrupted after flashing, leading to the security light being on all the time. I doubt that's what's going on here, but I thought I would add that experience just in case others are reading this thread trying to diagnose similar things.
Earlier this year after a round of troubleshooting, I had Efilive flashed my ECM back to what I thought was my stock tune and ended up with a no-start condition and security light on. Suspecting my original tune file had been corrupt somehow, I figured it would be best to just start with a clean slate. So I sent off my ECM to SoCal Diesel to have it flashed back to a clean stock tune, with the vehicle security stuff turned off. When I got it back the truck started and ran fine but the security light stayed on in the cluster. Scanning with my CTS2 and with my Efilive Autocal showed no codes. Lorenzo@SoCal had me send the ECM back to him where he did some repair work on it beyond just a simple reflash. When I got it back, no more security light.
In my case it seemed that something in the ECM died or got corrupted after flashing, leading to the security light being on all the time. I doubt that's what's going on here, but I thought I would add that experience just in case others are reading this thread trying to diagnose similar things.
Thanks for the help guys
I won’t get a chance to mess with it anymore until next week at some point.
I won’t get a chance to mess with it anymore until next week at some point.
U1152 means the HVAC control module has gone silent for 5 seconds or more on the class 2 data bus. This really doesn't have anything to do with your security light problem, except the serial data bus being shared among all the modules (ECM, BCM, TCM, DDM, etc)
Have you tried clearing, and it comes back?
Have you tried clearing, and it comes back?
Yes. I think he did
We unhooked the batteries for about 10 mins
Disconnected the BCM and plugged back in
He is leaning towards a pass lock module
Hi Joe,
A failed ignition key passlock module should have a code stored in the BCM.
If your tech is using the GM Tech 2, he should be able to read all the VTD (vehicle theft deterrent) parameters which should provide a diagnosis. I was speculating earlier that the system might be in "Fail Enable" mode since your truck still runs.
I snapped a couple screenshots for you to illustrate. One is the theft deterrent Security Data screen from the BCM, the other is the VTD status from the Powertrain (ECM) Engine Data 1 parameters. "Monitor Passlock" state is normal. Also the "PCM/VCM in Fail Enable" parameter could be interesting.
I had an ECM failure which acted the same way. Might be worth picking up a used one to have on hand as a spare anyway. If you buy another ECM and try it out, you will need to the VTD relearn procedure to re-marry the ECM and BCM together. It's documented somewhere on DD.
A failed ignition key passlock module should have a code stored in the BCM.
If your tech is using the GM Tech 2, he should be able to read all the VTD (vehicle theft deterrent) parameters which should provide a diagnosis. I was speculating earlier that the system might be in "Fail Enable" mode since your truck still runs.
I snapped a couple screenshots for you to illustrate. One is the theft deterrent Security Data screen from the BCM, the other is the VTD status from the Powertrain (ECM) Engine Data 1 parameters. "Monitor Passlock" state is normal. Also the "PCM/VCM in Fail Enable" parameter could be interesting.
I had an ECM failure which acted the same way. Might be worth picking up a used one to have on hand as a spare anyway. If you buy another ECM and try it out, you will need to the VTD relearn procedure to re-marry the ECM and BCM together. It's documented somewhere on DD.
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He definitely has a tech 2. It looks just like those pics.
I don’t remember exactly what he said but he can’t communicate with the VTD at all. He did a couple pinpoint test per GM though and that’s what leading him to this.
I talked to my buddy at GM yesterday. I can try a new pass lock module out and see if it fixes it. So if it doesn’t I’m not out anything.
Another thing that we found out was the ignition cylinder is so worn that you can pull the key out while it’s running so no clue if there’s something going on In there. So once this gets fixed that will need to be addressed.
Here's something interesting that might help - I've seen the same thing. On my Tech 2, the top menu is
F0: Powertrain
F1: Body
F2: Chassis
F3: Diagnostic Circuit Check.
Now, within the Body menu, there is a bunch of selections. One of those is "Vehicle Theft Deterrent". If I choose that, it gives me a communications error. I bet that's what your tech is seeing.
To get to the screens I posted above, go in the Body menu, and select "Body Control Module" (not Vehicle Theft Deterrent) then "F1: Data Display" then "F3: Security Data". Also you can get the 2nd screen I posted above by going back out to the top menu, starting on Powertrain, and navigate down to "Engine Data 1" parameters.
Regardless, sounds like a new lock cylinder is a good idea anyway.
Not yet buddy
Life got busy. Work got busy. The country has decided to put everything on a halt and work has started to slow so I kinda stepped back from it for a little while. The daily needed some work done also it was a necessity type of thing on it so I had to do it.
Once things settle down I’ll get back at it.
Were you able to solve this? I'm having the same issue.
I tried to check my security light with the tech2, and I can see where it's requested, but I don't know enough of the other values to know which one is out of spec to cause the light. Does anyone have experience troubleshooting this with a tech2?
I tried to check my security light with the tech2, and I can see where it's requested, but I don't know enough of the other values to know which one is out of spec to cause the light. Does anyone have experience troubleshooting this with a tech2?
As you can see from my snippings, PCM / VCM Fail Enable is YES and the passlock state is Normal Decision.
Would a relearn fix this? I do recall doing one when I first got the truck many years ago....
Would a relearn fix this? I do recall doing one when I first got the truck many years ago....
Assuming you're having the same problem as the OP, where the truck starts and runs fine, but the security light stays on?
Normallly PCM / VCM in VTD Fail Enable means the ECM and BCM stopped communicating sometime after the initial ignition cycle. The BCM sends a password to the ECM at engine start, and if it's not received at that time, the truck wouldn't start. While the truck is running, any interruption in comms between the BCM and ECM will cause the security light to turn on, from my experience.
Sorry I forgot to ask. Have you scanned the BCM for Bxxxx codes, if so post them up.
Normallly PCM / VCM in VTD Fail Enable means the ECM and BCM stopped communicating sometime after the initial ignition cycle. The BCM sends a password to the ECM at engine start, and if it's not received at that time, the truck wouldn't start. While the truck is running, any interruption in comms between the BCM and ECM will cause the security light to turn on, from my experience.
Sorry I forgot to ask. Have you scanned the BCM for Bxxxx codes, if so post them up.
Yes, the exact same problem. I've had the truck for about 4 years, and the light was on from when I purchased it.
BCM is under the steering column, and ECM is on the fan shroud, correct? Do you know which pins connect the two computers?
One other thing, my security light is on from the time I turn the key to "ON", through start, and then finally turns off when the truck is turned off. I had the tech2 connected while starting and I didn't see the security light state ever say OFF. I'll watch the VCM / PMC In VTD Fail Enable as I start the truck.
BCM is under the steering column, and ECM is on the fan shroud, correct? Do you know which pins connect the two computers?
One other thing, my security light is on from the time I turn the key to "ON", through start, and then finally turns off when the truck is turned off. I had the tech2 connected while starting and I didn't see the security light state ever say OFF. I'll watch the VCM / PMC In VTD Fail Enable as I start the truck.
Any codes stored by the BCM?
Yes, BCM is under the steering column and ECM is under the hood down low on the drivers side fenderwell below the battery. The TCM is the module mounted on the fan shroud.
For the ECM - BCM connections, see post #15 in this thread. It's one of 2 serial busses.
Yes, BCM is under the steering column and ECM is under the hood down low on the drivers side fenderwell below the battery. The TCM is the module mounted on the fan shroud.
For the ECM - BCM connections, see post #15 in this thread. It's one of 2 serial busses.
Oh shoot forgot to type it out but, yeah no codes from the BCM.
I'll take a look at the connections and make sure they are in good communication with each other.
I'll take a look at the connections and make sure they are in good communication with each other.
Truck still isn’t fixed on my end. Just got back to making money and trying to build the savings back up.
and the icing on the cake was the FICM went out Sunday. So I got that to deal with.
and the icing on the cake was the FICM went out Sunday. So I got that to deal with.