I am a relatively new 2002 C5 owner. (33,000 miles on the car) I have some issues that I am correcting after a rear end collision, and a month in the body shop. One problem I have that I am not sure has any relation the the colision, is the car will not crank, when warm. It appears the theft deterant system will not engage the starter, (no click). This has happens after tha car has been run a while, is warm, and then stopped for 10 minutes. after fiddling with things it usually come back 10 -15 minutes later. The last several times I disconnected the negative barrery terminal at this appears to speed up the recovery.
Replaced Battery, cleaned the keys (all three keys have the same issue)
There was an excellent post on repair of the ignition switch, but since my problem is when warm, I am thinking this is a long shot.
Anyone have this problem or can point me in a direction ?
This weekend was planning to go in and check the Battery grounding connections, since this appears to happen when warm.
Arizona is starting to get warm, and this issues I fear will get much worse.

 

...from Bill Curlee:

There are a number of things that could cause this but here are the BIG THINGS that it usually turns out to be………..

First things first!! When it fails to start/crank, HOLD the ignition key over to the START POSITION! (assuming you have an NM6) While HOLDING the ignition switch to START,,,, make and break the clutch switch by slightly pressing and releasing the clutch pedal on and off the clutch switch.

When you make and break that switch,, you SHOULD hear the Theft Deterrent Relay (TDR) in the passengers foot well click ON & OFF. IF,,, you hear that, at least you know that the LOW current side of the TDR CRANK CIRCUIT works.

The OTHER half of the TDR is the HIGH CURRENT side and it supplies 12 VDC (60 AMPS) to the STARTER SOLENOID thru the PURPLE WIRE. If you have 12 VDC on the PURPLE WIRE when the TRD is energized,,, You MOST likely have one of two things wrong.

1. The connections at the starter solenoid are "loose, dirty, corroded, damaged or the solenoid terminals are broken.

OR

2. The Starter Solenoid had an internal issue causing it to fail intermittently! THIS MY FRIEND is a EXTERMELY COMMON and WELL DOCUMENTED C5 & C6 PROBLEM! If it were ME, I would just change out the solenoid if that is determined to be the issue. But that’s ME.

When this issue happens,,,,, If you can RAP the solenoid with a mallet, I bet you a cold one that the starter would magically crank!

So,,,,,,,,,,,,,,,,,,,,,,, My bet is you have a defective starter solenoid.

YES YOU CAN just change the solenoid. If you can find one in the parts store, it about $40-$50 BUT,,,,,, ,,,, you must completely remove the starter to change out the solenoid. I found mine in a starter / alternator repair shop and changed it out which solved the issue 100%

 

Bill,
Thanks for the excellent reply. I forgot to add my C5 is an automatic. However I believe you nailed it, the solenoid is the issue and I plan to replace it this week. Thanks again for your help.