I am the proud owner of a Silver Metallic 2002 C5 Coupe, my first Vette but I've run into a real 'head-scratcher' problem, which apparently even the Chevy dealer here can't diagnose (at least to this point). Approx 2 weeks ago, I started noticing that when I would press the "AC" button to turn on A/C, after 2-3 seconds the LED would go back "off" and the A/C Compressor would shut off. I've now had the car in the dealer 4 times and they can't find the problem. To date they've replaced/reprogrammed the main ECM, and the A/C Elec. Module. Diagnostic checks have been run and the codes indicate to the dealer that there's no problem. They are talking with Detroit at the Tech Assist Center who are trying to help find/diagnose the problem. Today they hooked up an electronic "black box" and instructed me push the red button on the activating switch and any aberrant data would be collected to be relayed to Detroit. While the A/C light going off/blinking twice, going off
issue has ceased, I've now encountered a new problem. While driving the car, without warning, the whole dash lights up (all the warning symbols displayed) for about 1-2 seconds and the speedo, gas gauge, and other needles return to the 'engine off' position and then return to original position. This occured 4 times over a 6-8 minute period. The lit LED on the activator switch for the diagnostic box hooked to the car would go out, I had to re-activate and then press again to, hopefully, capture any relevant data. Has anyone ever run into this electrical issue? If so, was it solved, and how. Any help/direction/advice would be appreciated.

 

I can't remember if it is the BCM or PCM, that sits underneath the battery, and can cause the car to act strangely if the battery leaks acid on it.

Seem to remember, from reading previous threads on the acid leak topic, that the symptoms were different though. My '02 has the AGM battery which isn't supposed to leak. But it may be worth a look.

Good luck.

 

Will have them check battery type, thanks.

 

I think Roscoe's on the right track..... I also remember something
about the acid disturbing a ground connection, causing the
symptoms you describe.

 

Thanks a lot for the helpful advice, you're the 2nd person to suggest
that it could be a battery leakage issue. I'm having a sit-down meeting w/the dealer Tuesday (7/6) so I'll bring that up.

 

Another area to check is the BCM!!! It is in the passengers foot well area and prone to being subject to moisture! My BCM had corrossion on the back of the circuit board as a result of moistuire in the passengers foot well and it gave me some VERY erratic and strange problems!!

I replace the BCM (had to have the dealer program it @ $73) in my 98 Coupe and my problems were resolved!

My moisture problems were the result of a CLOGGED AC/ Heater box drain and the hose that connects to the AC fan motor to the air box will condensate and drip water on/near the BCM. I insulated the hose for the motor and removed the fitting for the AC/heater box drain to fix the underlying cause of all my problems!!

You can remove the BCM from the vehicle and take the circuit board out of the metal shield box (WARNING-- Observe ALL ESD grounding precautions), and examine the circuit board for white corossion deposits. If there are any the BCM needs to be replaced!

Hope this gives you another path for resolving the problem!

I do not know how you will be able to get the dealer to understand how you came to the conclusion that the BCM is bad because removing the circuit board from the shield box will get you into trouble with GM for warrenty claims!

BC

 

Thanks a lot!! This has really got the dealer here in Houston, Tx stumped. They've been on the phone w/Detroit and Bowling Green. I had to have a "black box" of sorts connected to the car to try and determine cause. I'll query them about the BCM as well as a battery-related issue another member suggested. Thanks for your help, much appreciated!!

 

Per the dealer, they've replaced the BCM, so I no longer see that as an issue.
Also, they checked the battery (acid leak issue), and there's no problem there. Apparently what the problem/solution is basically, when you activate the A/C, just elevate/lower the temp for needed changes and refrain from pushing the A/C button "on/off" repeatedly. Also rapid temperature changes are supposed to be avoided. GM's Tech Assistance Center put out a bulletin regarding this matter. It appears that if a 97-03 C5 owner either pushes A/C button on/off several times or adjusts temp up/down too quickly, it sends a false 'feedback' signal confusing the A/C Control Module, causing it to have to be re-programmed. I want to THANK ALL MEMBERS of Corvette Forum who rendered helpful assistance. Thanks guys!


[Modified by 02Slvrvettecpe, 2:30 AM 7/7/2004]


[Modified by 02Slvrvettecpe, 2:31 AM 7/7/2004]

 

Roscoe, don't bank on that AGM battery. I also have a 02. Over the holiday, my wife took a road trip in the vette. After a rest break, she tried to start the car, and it was dead. AAA got her jumped and she made it to her friend's house. Saturday, Chevy sent a flatbed and took it to the local dealer (thank god I'm still in the 36 mo roadside assistance.) 5 hours later, after a new battery, and an acid cleanup, (under warranty) she was on her way. Unfortunately, since she was 500 mi away, I couldn't inspect the bad battery (and obviously didn't want her transporting it back.) She did mention that the gages started acting funny prior to the failure. So keep an eye on that AGM.

BTW- It's the PCM under the battery. BCM is in the pass footwell, and subject to AC leaks.

 

Nothing to add about the BCM,PCM, etc., but I did have an issue with a leaking heater box. The dealer thought it was cracked box because it dumped about a quart of water on the passenger side floor. A quick towel mopped it it up and none ran onto vitals below foot board. After seeing the dash torn out and intake manifold off to get the heater box out they/dealer found out that the factory some how left a wad of silicon grease about the size of a 50 cent piece. It took 12,000 miles to make it's way to the drain hole which is about 1/2" dia. infront of the fan motor. The dealer could not "snake" it open because of a 90 degree bend in the drain line. GM reimbursed me even though car was out of warrantee. The tearout was $1700!
R Mackow