Two intermittent electrical problems
 

2002 Coupe. MN6, F45, HUD, etc. Only mod is a cat-back. 73,000 miles. Newer battery (less than 1 yr old), new ignition switch. NO DTCs through the DIC or Tech 2.

Problem 1: Active Handling will engage when I'm cruising down the highway doing 65-70 mph. I'll feel a slight brake application for about one second and then it's done. It doesn't jerk the car in any direction. This happens ~3 times per week.

Most common fault is the steering position sensor, but from what I've read that usually causes at least one code. Same with the EBTCM. I have a VERY respectable dealer here that said w/o a code to start with, all they could do is put labor hours into it. That doesn't work for me. Ideas?

Problem 2: I took a video to demonstrate this problem. This problem happens maybe once a month. It seems to happen EVERY morning after doing a high speed run of 130+ mph. When I turn the key over to the 'start' position I get a no start condition. The starter doesn't turn, you can't hear the fuel pump, etc. After a COMPLETELY random amount of time/tries, everything just magically works like it's supposed to and the engine fires right up. To rule out the neutral safety switch I tried starting the car w/o depressing the clutch and I can hear the fuel pump but the starter never turns.

http://s61.photobucket.com/albums/h80/jwelshjr/?action=view&current=2012-04-22_08-12-31_570.mp4
I saw a diagram of the various ground locations and there are two, one on each side, that look to be around the base of the seat belt mounting point. Are these locations inside or outside the car? The reason I ask is because I also have water leaks that I haven't found and have had water down behind the seat belt trim and the carpet behind the seats.

I appreciate any help you guys can offer. Want to try here before I hit up CF.

Thanks,

Jeff

Both may be Ig. Sw. even though you replaced it

Problem 1:
Most likely (but not definitely) the SWPS. Mine did exactly what yours did for quite a while before it finally erred enough to start throwing C1287/1288 codes.
What's happening now, is yours is erring just enough to falsely engage AH, but not enough to toss a code and deactivate the system. It will probably get worse, and when it does, it will throw codes, but unfortunately it is a guessing game as to what sensor until then.



Problem 2 has numerous possibilities, and intermittent no-cranks can be frustrating to troubleshoot. Here is what I did...

Remove the pass side floor mat and access panel. Located just above the BCM (big silver box), you will find the Theft-Deterrent Relay (TDR). This relay is where everything in the starting circuit comes together and if you have a voltmeter, keep it there on the pass flloor, because you need to check things mainly when the problem is occurring. If the car starts, there is no problem, and a meter can't help. You have to be lucky to catch it when it won't crank. Also examine the relay itself, I've seen cases where corrosion set in and connections burned/melted.

There are 4 wires connected to this relay:
-A thick red wire, which is a direct feed from + battery. It does go through a 50a fuse, but it is obviously not blown given an intermittent condition.

-A yellow coil wire, which will have +12v (during an attempted crank) assuming clutch pedal switch is made, and ignition switch contact is made.

-A yellow/black striped coil wire. This comes from the BCM, and this wire is normally nothing, until the VATS (key pellet) system is satisfied, the BCM will then switch this wire to ground (-12v),which with +12v on the yellow coil wire, will combine to energize the TDR.

-A purple wire. This is the output wire that runs directly to the starter solenoid. Simply put, if you find +12v on that purple wire during an attempted crank, but the starter isn't cranking, it's the starter/solenoid that is bad. :yesnod: This is the first wire to check when the problem is happening. If it gets voltage when trying to crank, the TDR is energizing and everything else upstream is working properly. If nothing, then you can start backtracking, depending on which wire isn't doing what it's supposed to.

It took me a long time to have the car "not start" while I happened to have the meter in the car, and this is how I determined when my starter went bad.


Hope that helps.
:cheers:

You rock dude. Will definitely have to try this.

I just read a few threads about the BCM and it's sleep/wake up issues. So far I have no signs of the BCM being stuck in sleep mode.

This morning the "no start" condition occurred. I was running late so I didn't have time to check voltages at the relay. What I did do is held the key in "start" and pumped the clutch pedal. I could hear a relay clicking as I did this and am not sure if it's the TDR or one of the other relays down there.

Yes, that's likely what you heard, and that's a good thing to hear, 'cause if the TDR is energizing, it rules out just about everything on the control side of it. (clutch sw, ign sw, security).

It is looking quite likely you'll be replacing the starter soon. :yesnod: