Well I noticed that my security light will come on after driving about a hour. I have replaced my lock cylinder and ignition switch but still get the same code. The only thing I have not replaced is my key. I do have a new one and going to have it cut this week or weekend. Any other suggestions? Thanks.

 

I've seen some members hit the problem when too much weight hangs on the key. That allows the VATS pellet to shift in the ignition barrel and it loses contact bringing on the security light. If you replaced the ignition barrel, you can discount that.

I'd say you're on the right track with the key. Does it occur with the spare key too?

 

It does occur with the spare key but my spare key was the first key I used and is in the same wear condition as my current key. I am going to try to get this new key cut and then only use it on its own key ring.

 

As always........the first step is to post your codes.

http://www.c5forum.com/ayc/dtcdic.php

 

Sorry.

P1626 Theft Deterrent System Fuel Enable Circuit

 

..and that is the ONLY code?

 

For the security light yes. I have some other codes but none which are current and they deal with my hvac system as one of my actuators is starting to go out and getting stuck.

 

Ok.

 

That's it?

 

Went and had the new key cut and right when I turned on the car boom code. P1626 and it continues =]

 

Thats not one I've ever heard of Derty.

Here's the procedure from the manual if it helps. Looks like the options are limited.

DTC P1626
Circuit Description

The body control module (BCM) produces the theft deterrent crank relay and fuel enable signal when ignition is ON and the proper ignition code voltage value is detected. The powertrain control module (PCM) monitors the fuel enable signal during crank. If the proper signal is present on the Class 2 Serial Data Circuit, the PCM enables the fuel delivery in order to allow the engine to start. If the PCM determines that the fuel enable signal is not present or incorrect while the engine is running, DTC P1626 is set. The engine continues to start and run as long as DTC P1626 is stored. If the problem affects inputs to the VTD signal, the starter motor may be disabled.
Conditions for Running the DTC

The engine is running.
Conditions for Setting the DTC

The PCM has detected a loss of the state of health serial data message from the theft deterrent system.
Action Taken When the DTC Sets

The body control module (BCM) send a class to message to the instrument panel cluster (IPC) to illuminate the SECURITY indicator.
The powertrain control module (PCM) will not illuminate the malfunction indicator lamp (MIL).
The PCM will store conditions which were present when the DTC set as failure records data only. This information will not be stored as freeze frame data.

Conditions for Clearing the DTC

A history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The DTC can be cleared by using a scan tool.

1


Did you perform the Theft Deterrent Diagnostic System Check?


Go to Step 2


Go to Diagnostic System Check - Theft Deterrent

2


Important

If a loss of DLC data has already been diagnosed, clear this DTC and continue diagnosis with Diagnostic System Check - Engine Controls in Engine Controls - 5.7L.

Is DTC P1631 set as a current code?


Go to Diagnostic Trouble Code (DTC) List


Go to Step 3

3


Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?


Go to Step 5


Go to Step 4

4


Important

The replacement powertrain control module (PCM) must be programmed. Refer to Programming Theft Deterrent System Components .

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in Engine Controls - 5.7L.

Did you complete the replacement?


Go to Step 5


--

5


Use the scan tool in order to clear the DTCs.
Operate the vehicle within the conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?


Go to Step 2


System OK

 

Sorry, happy hour started early here Unfortunately, it sounds like communication is being disrupted between the BCM and PCM. Hard to say which is the culprit. Any moisture on the passenger floorboard?

 

No moisture on the passenger floorboard I also shot wires from the PCM last time this showed up. I checked all wiring that I could see/put my hands on. Only thing that I have not replaced is the PCM itself. But, that is expensive. I believe my last option is to make resistors to have the code permanently there.

Going to try using the key itself on the way to work today and for awhile to see if that helps. Everything is new such as lock cylinder and ignition switch. The new key threw the code within 5mins of driving home from the locksmith. The key I usually use did not........so I am going to use it by itself. Other than that might look into making those resistors.

 

Try this... Clear codes while engine is running... Turn the key off.. then unplug door harnesses L/R plug them back in... I too was having the issue with the Security light staying on along with the TCS/ABS... Consulted Bill Curlee.. NO LIGHTS, Codes!

 

Not for this issue.

 

Which wires did you check specifically? Bypassing the lock cylinder with resistors will not help your cause in this case. If the BCM was loosing the resistance value, it would trip a B272X code. Just to be clear, you are checking the codes with the DIC, and not a scanner?

 

Yes, checking codes with the DIC. I check it right when it pops up when driving and its the exact same code every time. I can't remember which wires I shot been awhile and have to look at the wiring diagram again. I was shooting for continuity from the pcm and the ignition. Shaking whatever wires I could get my hands on and never lost signal.... The funny thing is it does not happen when driving to work and home everyday but once I take a trip that is over a hour or so it comes up just seems odd.

 

Oh I also have checked the door connectors for corrosion and such but didn't find any. I still cleaned them with contact cleaner.

 

derty01

Just for grins (hell, what’s left to check) disconnect the battery and then remove the BCM and take the circuit board out of the aluminum box.

(CAUTION) "The BCM is ESD Sensitive!!!!"

Don’t ZAP it with static electricity!


Use a magnifying glass and carefully look over all the circuit traces and solder joints. A cold solder joint can and will cause this issue along with other weird things.

Also look for corrosion (white deposits) on the circuit board and under the mounted components. Inspect the connector that the resistor wires go to and make sure that the pins in that connector are clean, and the female pins are not spread apart.

Look at the circuit board for that connector and make sure that the solder for the connector pins is not damaged or improperly soldered.

Sounds to me like you could have a poor connection on that board somewhere. The little surface mounted pull up resistors seem to have problems quite often on a LOT of GM Circuit boards.






TWO of the WORST poor solder joint offenders are the HVAC Control module and the EBTCM Circuit boards. Look at all the crappy solder joints on this board:



That’s the condition of the board right out of the module.

BC