I have an 02 6spd duramax that will not start. batteries are good, good conection. truck will power up but does nothing when turned to crank. I thought mabye it might be a problem in the clutch sensor. any sugestions, thanks Zac.

Moved to Duramax First Generation: 2001-2004 (LB7)...

Mine has done that and it's a loose bolt on the starter that holds the hot wire. This is on my 03 6spd. There is a sensor too but I haven't had issues on either of mine with it.

System Description
-The +12V, (Hot all times), is supplied to IGN C Fuse 20A, (Fuse Block Underhood), ORN wire.
-This goes into START contact on Ignition Switch, and out on yellow wire to CRANK Fuse 10A, (Fuse Block Left Instr Panel.
-LT GRN wire out of CRANK Fuse to Clutch Start Switch.
-PPL WHT wire out of CSS to the coil of Starter Relay, (located in Fuse Block Underhood).
-The Starter Relay is connected to ground G106, BLK wire.

-The contact of Starter Relay is supplied +12V from IGN A Fuse 40A, (Fuse Block Underhood), which is HOT at all times.
-PPL wire out of Starter Relay contact goes to Starter Solenoid Coil.

Troubleshooting
Feel Starter Relay in Fuse Block Underhood while someone tries to start truck, (with clutch depressed of course). If this relay consistantly clicks in START, monitor +12V on PURPLE wire at starter. If +12V is present during START, the starter or its solenoid are bad. If no +12V at PURPLE wire on starter, either Starter Relay in Fuse Block Underhood has a bad contact or IGN A Fuse 40A is bad.

-If while trying to start, the Starter Relay, (Fuse Block Underhood), does not click, check IGN C Fuse 20A, and CRANK Fuse 10A.
- Position transmission in NEUTRAL, aand apply Parking Brake

CAUTION: The next step will allow engine start with clutch NOT depressed

-To test for bad Clutch Start Switch, at CSS jumper LT GRN and PPL WHT wire, attempt to start.
-Remove jumper at LT GRN and PPL WHT wire
-Replace Starter Relay with new, (or borrow simular relay from another circuit).

To test starter directly, (not sure how accessable), at starter, momentarily connect jumper from heavy gauge RED wire to PURPLE wire.
-Verify good grounds at starter and batteries.

http://www.dieselplace.com/forum/showthread.php?t=113089&highlight=clutch+safety+switch

Post #6 has the plug diagram for the clutch safety. Jump C & D. If it is out you'll need the whole clutch master cyl assm to get just the switch. I was able to remove just the switch without changing the master cyl.

If it is bad do a search in the ZF OEM section for clutch switch.

thank you very much for your input, I appreciate it. I am getting the garage warm as we speak. I am going to pull start it first to get it running. Thanks Zac