2002 XL won't start; bizarre electrical problems after dealer throttle body cleaning

[mamalaren]

'02 Denali XL, 8th VIN#U, miles - 70,250.

This is a weird one. Last week, a/c was blowing hot; PEP boys said problem was electrical. Dealer found no a/c problems; performed throttle body cleaning and PCM update to address low idle causing intermittent a/c compressor operation. (Compressor was replaced under warranty in '04). $350, and kept car overnight, so had to get a rental.

3 days later, after bb gun shattered side window (sheesh!!), had doors open 1+ hour for police to inspect, car would not start. Turned key, nothing. Some lights and power. Then removed key while sitting inside vehicle, doors closed--warning chime sounded (as if key left in ignition with door open, or lights left on). Also, clicking sound -- fuel and temp needles cycling up to 1/2, then back down.

Called dealer, attempted keyless remote reset, nothing.

Tow truck successfully jumped, but then could not accelerate over 10 mph. Towed to dealer (evening).

Next morning, dealer called, it started right up--could not replicate failure. Car fine for 2 days. THEN . . .

Today, kids washed car--doors open about 1 hour. Again car will not start.
Waited several hours, still won't start. Tried someone else's fix of turning key backward (into accessory mode), leave for 10 minutes, then try to start. Unsuccessful, but now constant chiming--even after 30 minutes!

Finally got chiming to stop by leaving key in ignition, turned slightly forward (not all the way to start). Locked car manually with another set of keys.

Bizarre! any insight appreciated. Thanks.

[maxwedge]

Welcome to AF. Look for bad grounds, if ok I may suspect the ign switch itself. Realistically checks must be made when this occurs.

[mamalaren]

Hi,

thanks for your response. Actually the ignition switch had already been replaced last week when it was in for the a/c (I just noticed that on the receipt today).

Still did not start this morning--battery tested dead and poor cable connection, alternator ok. No more chiming. Jumped it and drove to Pep Boys for new battery. We are checking for the grounds too. We'll see . . .

[WEF]

Bad battery?

[mamalaren]

Yes,

It does appear to have been a bad battery! Thanks for your replies.