In my '01 Coupe the headlights pop open when the car is started. Then after a few seconds they close. However, this typically only occurs when first starting the car. Any recommendations on how to get this taken care off? Thanks.

 

Have the headlight motors been making any funny noises or sticking?

 

Hmmmmm,, Another Connecticut Corvette owner! Hope you came thru the storm OK!

There are several things to look at but lets concentrate on this theory first:

Are you losing any other stuff. Example: Trip mileage, MEMORY stuff, HVAC goes to default settings, ect.

If so, that would indicate that you battery is not able to handle the job of supplying the proper voltage at start up. When your battery is very low on charge OR it's getting OLD, it is able to supply the CURRENT necessary to crank the engine but,, the voltage output of the battery will be insufficient to support all the modules in the car.
As the engine starts to spin up, the voltage gradually rises to the point where the modules function again leaving a History DTC in the effected modules.

Simple to test. Get a AC/DC Digital Voltmeter. Attach the meter to the battery terminals and have someone COLD START the engine. Record the LOWEST voltage that you see during cranking. If your dropping down below 10.0 VDC, (I have see it drop down as low as 9 VDC and the engine still cranks just fine) your loosing voltage to critical modules throughout the car and they are shutting down. One of those modules is the head light control module.

Examine your DTCs and see if you have any DTCs related to loss of voltage. Especially in the Door Control Modules. They are the most sensitive to voltage loss. You will also see a lot of U series history DTCs if the module is loosing comms and voltage.


If you don’t know, Heres how to read the DTCs:



READING YOUR Engine Diagnostic Trouble Codes (DTC)

This procedure should be carried out any time you experience a problem with your C5. Most inexpensive store bought aftermarket code readers will ONLY read power train DTC’s. Reading the DTC’s with the C5 built in code reader will allow you to read ALL the modules in the vehicle.

The Diagnostic Display Mode is entered with the following procedure:
1) Turn on the ignition but don't start the engine.
2) Press the RESET button to turn off any warning messages. (i.e. door open, trunk open ect)
3) Press and hold the OPTIONS button
4) While holding OPTIONS, press FUEL button four times within a 10 -second period.

Initially, the on-board diagnostics go into an Automatic Mode which will cycle through each module and shows diagnostic codes in a pre-set sequence: PCM - TCS - RTD - BCM - IPC - RADIO - HVAC - LDCM - RDCM - SCM - RFA. All codes will be displayed for each module. ( i.e. PCM = 4 codes) If none are present in a given module, you will see No More Codes on the display.

There are two types of diagnostic codes, Current and History designated with a letter suffix, “C” or “H”. A current code indicates a malfunction is present in the module displaying data. A history code indicates a problem existed sometime in the last 40 or 50 ignition cycles. When not accompanied by a current code of the same number, it's potential evidence of a previous problem, now resolved, that was not removed by clearing the codes. More likely it's an indication of an intermittent malfunction.

Intermittent codes are the most challenging of the diagnostics. An intermittent code may have happened once, may have happened more than once but is inconsistent or may be happening on a regular basis but not at the time the codes are displayed. History codes can also be caused by a current malfunction in a system that is not operating at the time codes are displayed. An example is the rear window defogger which doesn't operate until the Body Control Module detects engine rpm. For history codes set by a module that does not operate with the key on and engine off, a special diagnostic tool called a Scan Tester is necessary to properly diagnose the malfunction.

Once the system has displayed all modules, it goes into the manual mode which allows selection of each module using combinations of Driver Information Center buttons. Manual mode can also be entered during the automatic sequence by pressing any button except E/M. Once the display shows Manual Diagnostics, select a module by pressing the OPTIONS button to go forward or the TRIP button to go back. Once a module is selected, a code is displayed, and if more than one are present; press GAGES to go forward or FUEL to go back.
To exit the diagnostic mode at any time, press E/M. If you want to erase codes in a given module, press RESET To reset the codes once in manual mode, press and hold RESET until it displays NO CODES Press OPTIONS to go to the next module. Repeat the steps until you have reset the codes in all the computer modules.
NOTE!! Only reset the codes IF you want to - it is NOT necessary to do this. Clearing a code does not repair a problem. You are simply erasing the evidence of it in the module's memory. If you clear the code/s, and extinguish the Check Engine Light, your emissions status ready will NOT allow you to pass an emissions test until you have completed the required driving cycles. There are a few body module DTC’s that if set will prevent the module from operating properly. Once the DTC is cleared, the module will return to full function. This is not true for power train DTCs.

If you have never read and cleared your codes, there will probably be a lot of old history DTCs. It is recommended that you clear your codes and see if any come back during a driving cycle. Those are the ones that you need to concentrate on diagnosing.

Once you have the codes, the next question is: What to do with the information?
First, consult the factory service manual. Any serious C5 Do-It-Yourself owner should invest in the Corvette Service Manual of the appropriate model year. The Service Manual is really a requirement if you want to understand and work on your C5.

You can read the DTCs while the engine is running. If you turn the engine OFF and then back ON, that can clear some DTCs that may be important with identifying a problem. One example is a Misfire DTC (p-0300) If the engine is shut down, the DTC will clear.

These are some very good C5 Diagnostic Trouble Code (DTC) explanation web sites!!! They also explain how to read the DTCs

Here is a very good PDF on DTCs and what they relate to:

http://forums.corvetteforum.com/c5-t...odes-dtcs.html


Here are some very good sites that explain what DTC mean:

http://www.gearchatter.com/index10.php

http://www.obd-codes.com/


*** Make sure to include the H or C suffix when you post your DTCs!! They are important!!!

Updated 13 September 2012 :-D

Post the results of your test and if that is not the issue, I have some headlight specific areas that you can examine.

Bill

 

Yeah,,, Thats another area to check out. I keep forgetting about that STUPID thing. Never had it so it never effects me. Good recommendation.

Bill

 

Thanks for all the input. I will do some diagnostics tomorrow. I will begin with the twilight sentinel feature, which I never have used in the past. Battery is an Optima, about 5 years old, but when the car is not in use, it is on a battery tender. No funny noises or sticking problems with the headlight motors.

 

Okay, it seems I inadvertently had the twilight option on. I always had kept it on off. The battery is at 11.9 volts. Let's hope that the inconvenience is solved. Thanks again guys.

 

No, not so far. Although that is a good point. I had been thinking about a new battery, so maybe it is time for it. Thanks.
Question: Anything I need to be aware of to change the battery? Or just unplug and plug?