Security Light and Everything Reseting
Hi, First Post so bear with me Please.
I have a 2000 Pontiac Montana. 146k, 3.4 V6, with its few problems here and there, but rather trustworthy. However. 5 Days ago, While driving, everything jumped, (rpms noticeably, gauges, and overhead display ect.) and the 'SECURITY' light came on in the message center. From that point on, the engine would not maintain rpm, (would sway 1-200), the transmission would shift rougher, and the speakers would emit a clicking-static noise. Now, I am an Aircraft Mechanic, So I was able to troubleshoot it down to this.
-Idle rough, not maintaining rpm, trouble shifting
-Speakers emit clicking, regardless if radio is on/off Volume level
-only in drive
-Speaker noise worse when rpm'* are raised.
-Security light went out after restart, and stayed off
-No Codes or Engine lights
-Pulling Bat Cable to reset did nothing
This was the same day everything jumped. However again, it drove completely fine the next day, but has since started again, and has been getting worse.
Today, it is to the point where the speaker noise is much more prominent, in all gears. Rpm'* and Transmission still vary, almost like its trying to decide if it wants to shift or not. Overhead display is constantly resetting. Rough Starting, (if at all) and idle. and 4 times today everything resets, gauges flat line, all lights come on, everything resets, almost like you pulled the bat-cable. The security light also came back on temporarily in the mist of all this, only to go back out once restarted.
I have checked all fluids, the battery cable, battery, Alternator seems ok, and a few other things. This is obviously a serious electrical problem. A few shops I stopped at today suggested a bad ground somewhere, however I have little automotive electrical exp and I'm kinda scratching my head.
So, Any ideas on what may be causing this? BCU or ECU Maybe? The Owners Manual says when the security light comes on, it means the PASS KEY III module is malfunctioning, however I am unsure where that is to check it.
It seems to continue to start, (I have to give it some gas to go) and stay'* running for the moment, however as stated, it seems to be getting worse. (if I can just get to work the next 2 days then I'll have some time to work on it, no other car)
I can chase wires if I need to, but I have no clue where to start. I hoping I can get a few other suggestions here before it costs me 1-3oo$ at a shop just to tell me what it is....
I"ll be checking fuses now as well....
My Forward Thanks to any replies and or suggestions!