Sapper1recon

I have a weird problem.Out of nowhere my clock and other inside lights seem to dim when I apply the brake without the headlights on.Then my blinkers hyperflashed when turned on either left or right.Flashers seem to come on but make the other lights go dim also.Wife says no brake lights or flashers in back.Checked all fuses and they are good.Also headlights seem to be nowhere near as bright as they should be.Voltage reads 14.5 running,12v on not running.And on top of that now my alarm goes off when I lock my doors using the key fob.I'm dumbfounded!Help!

Jnape

How old is your battery? If you measured 12v with a dmm, that is low. Start there.....

yelovette

It sounds like a ground issue, the light are providing part of the needed ground, thats whats makes the light illuminate. Just like a c4 w/ the dash groung problem it lights the turn indicators but no dash light. Check the grounds I replaced the GM ground block w/ crimped eyelet connection on my c5 no more crazy issues. good luck

Sapper1recon

Thanks guys for the help.So far battery terminals are clean and I'm going to all my grounds to check them.Does anyone think it might be in the flasher switch?I heard brake lights runs thru it also,just a guess?

Bill Curlee

If you have no brake lights and flukey dash lights,, you could very well have a defective steering column MULTIFUNCTION SWITCH. There KNOWN to go south and will cause a lot of those issues:

-C5 Multifunction Switch repair - http://forums.corvetteforum.com/c5-t...f-replace.html

Something else to consider as a point of electrical issue. Its easy enough to take some voltage readingas and do a few checks:

-C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html

See if your displaying any 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 are some very good sites that explain what DTC mean:

http://www.gearchatter.com/viewtopic11755.php

http://www.obd-codes.com/trouble_cod...d-ii-codes.php

Make sure to include the H or C suffix when you post your DTCs!!

Sapper1recon

Thanks Bill!No codes to report.I'm taking battery to get checked tomorrow then will start working my way down the list.