FFIN90

I typed that in the search box and surprise, no results.
In the 10 years I've owned my 98 I've never noticed this before, so maybe it's normal ( although I don't think so ).
When I parked the car in the garage this afternoon (without the lights turned on) I noticed the dash lights and window control switches lights on the doors were on, the car was off but the ignition was still on and my foot was still on the brake pedal. When I removed my foot from the brake pedal the lights went out, then I pressed the pedal again and the lights came back on, they would do this every time I pressed the pedal.
Next I turned the ignition off and tried it and they flashed once and the alarm system went off, I think I have maybe picked up a hitchhiking electrical gremlin.

Anyone ever experience this issue, or is it normal and I just have never noticed it before?

NOTE: Battery is fine and no other electrical issues at this time and no codes on the DIC.

Bill Curlee

Well,, thats the absolute weirdest thing that Ive ever seen on a C5

Lets try this.. How did you check the DTCs???? If you didnt use the DIC to read them, please recheck. See if you have any DTC. List them all. If you have a LOT of them, clear them all and see what comes back.

That sounds just like a BCM issue.
Look in the passengers foot well and see if the BCM, carpets, under the carpets, under the seat etc.... are wet or damp. Feel under the carpets and under the carpets under the seat area.

Post the results of the wet damp look!


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.

NOTE and a WARNING. You can read the DTCs while the engine is running. I pull mine up all the time while driving.
WARNING. Don’t become distracted while reading DTCs while your driving and cause an accident!!!!! Use common sense and drive safe.

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!!

chaase

Fault in the twilight sensors?

The dash lights come on when I release the e-brake when its dark so maybe it is linked some how?

P.S. Is there a prize for stumping Bill.

FFIN90

Thanks Bill, that's how I checked the codes, none present, H or C.
Unfortunately we'll have to wait until Sunday to check the footwell, it's dark and cold out here now and I work a 24hr shift tomorrow. I will post up on Sunday to update you.

Thanks for the hint, I have a by-pass put on the twilight function, it's been on there for about 4 years now with no issues so far.
I was hoping Bill would chime in, I figured if anyone could point me in the right direction it would be Bill.

FFIN90

Bill, I checked the footwell area and all was dry. I also noticed that when stepping on the brake pedal the foglights also come on with the dashlights.
I also tried stepping on the pedal after turning the ignition off, the lights will go on for about 2-3 times before it will no longer do it.

I think I will try to make a video of what it is doing in the garage, might be easier to understand what's going on.

il504il

having the same issue with mine and none of my rear lights are working either... getting frustrating!

Bill Curlee

Well,,, The BCM turns on/controls the FOG Lights,, infact,,,,,,, ALL the lights that you say come on can be turned on by the BCM.

Lets try this. Disconnect the battery NEG cable. Touch it to the POS terminal and then reconnect it. See if your issue or symptoms change.

BC

FFIN90

Thanks Bill, I just got home from an out of town overnight trip, I will go out Sunday afternoon and give this a try.
Question, will this not cause a short or arcing of the cable and terminal? or is this what's it supposed to do.
Ray

Bill Curlee

NO! Your shorting the cables from the car together... NOT the battery terminals. Once the NEG cable is removed,, the car is ISOLATED from the power source.

BC

FFIN90

OK Bill, here's some video of what went on today, the one showing codes was after I disconnected the battery.

Bill Curlee

Well,,, Applying the brakes is not suppose to do that..

I will have to mull over that for a while. VERY STRANGE!!

FFIN90

could it be the BCM is on it's way out Bill?

mighty mousd

Maybe a bad ground ? I don't know but that is a weird one.

Bill Curlee

That was my very first thought. Heres my recommendation.

Disconnect the Neg BATT terminal, remove the BCM. Open the BCM Box and carefully remove the circuit board and inspect the circuit board.

Look for corrosion on the circuit board. It will be white or green deposits on the traces or under the components. Also check the connectors for corrosion and damage.

NOTE! The board is ESD Sensitive. Make sure you don't ZAP it with static.

If you find corrosion clean it with alcohol and a nylon brush.

BC

FFIN90

Thanks Bill, it will be a couple of days before I will be able to do what you suggest. I will update as soon as I can.

Ray

FFIN90

I am unable to get the car into a shop until next week to have a look at the BCM, the weather has turned too cold to be working on the car outside and my garage is not big enough.
I had the car out today for a few minutes and a neighbor of mine just informed me that when I backed it into the garage that the brake lights were not working.
I checked them with the lighting system off and on and NO brake lights either way, and the car was running. Also the rear running lights and side markers were also not working but the signals are and so are the headlights and front running lights.
Just to add to the mystery

99MALLETT396

It might have something to do with your brake switch since you don't have brake lights. It's worth checking.

dadaroo

It looks like you have the "best of the forum" helping you. I am going to subscribe to this issue to learn what the cause(s) are. I know the forum will help you fix this.

FFIN90

Thanks for the tip, will do just not sure when

I certainly hope so.

FFIN90

I've also been pointed to the hazard switch as there are a few circuits that pass through that switch I've been told. I'm currently stuck at trying to get the switch out of it's housing without removing the whole dash to put a volt meter to it to check it out. I can see a little opening on the bottom of the switch to push in on to release it but can't get anything into the area to push on the top release spot.