Richard A. Snitzer

Sometimes my instrument panel gauges, radio, window switches and who knows what else are not working when I turn on the car. It has, on occasion came back on while shifting. Don't know if it related to the problem, but I wanted to throw that in there as a clue for you mechanical Sherlock Holmes'.

Any thoughts on where to start the troubleshooting?

bjones7131

Someone else posted a similar issue last week. As I remember he tried a lot of different stuff and still no resolution. Sorry I can't help hope U get it ironed out.

Richard A. Snitzer

I searched in this forum before posting. Anyone know the thread bjones is referring to?

bjones7131

I just looked at it is is called ELECTRICAL GREMLINS currently on page 3 I believe posted by casey jones

dadaroo

Sounds like a typical ignition switch (electrical portion) issue. Everything that operates from voltage in "HOT in Accessory and ON" is powered thru that switch and it can cause a lot of issues.

Do you know how to use a voltmeter? If so you can check the fuses that are powered via it and measure the voltage at the fuses versus what you read at the battery. That can tell us if some contacts are burned. Very typical.

I don't think your battery is the issue but let's start with what the reading is AT the battery when the engine is OFF.


Mr. Sam

dadaroo

I don't think Casey's issues are similar and I don't think that Thread will help the OP.

Richard A. Snitzer

Holy Crap! I don't have near the problems this guy is having. But I would like to see how fast I am going either in the cluster or HUD. And turn the radio on every now and then.

wcsinx

Richard A. Snitzer

You may be onto something because the prior owner replaced the ignition due to some sort of common problem with it. The battery reads 12.4 V and was changed just a few months ago.

dadaroo

Huh???????? Replaced ignition?

Richard A. Snitzer

Yes he claimed he replace the ignition switch

dadaroo

Can you measure the voltage AT the battery when the car is sitting before you start it?

Then give us a reading there once the car is running.

If the battery is at 12.4 before starting then it may be getting drown down too low to support some of the electronics.


A fully charged battery should be 12.6v or more.

It's not 12 volts it's 12.6 because each cell is 2.1 volts.

If the battery is

12.5 = 85% charged
12.4 = 65%
12.3 = 50%
12.2 = 35%
12.1 = drained


Mr. Sam

Richard A. Snitzer

Readings:

Car Off: 12.6
Car On: 14.26

Update on conditions: I drove the car about 100 miles yesterday. And finally somewhere around 80 miles everything started to work again as I was driving on the Interstate. Don't know if this helps, but it is more data.

dadaroo

Thanks for the info, yes that type of info does help.

Time to pull your dash DIC codes and see what may be there. If you don't know how here is the info.


READING YOUR C5 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!!

NOTE!!! Start the car and let it idle. Then take it for a drive and cause the problem to occur. When you return home pull the codes BEFORE you shut off the engine.


Do NOT discount the codes with the H following them. They can provide an audit trail for issues going on with the car. They ARE important in diagnosing problems.

Post ALL the codes that you pull with the engine running..........

Some codes go away WITHOUT setting an H code when you shut the engine off. I suspect you will have several codes that will show C or HC that do NOT show when the engine is turned off.


Mr. Sam

Richard A. Snitzer

Well...went to pull codes this morning and we are back to unresponsive gauges. So, whenever they decide to work again, I will pull the codes and publish.

update Information: It did rain last night and the car sat outside.

73Corvette

Check the passenger side carpet and see if it's wet/damp... pull the foot well cover where the BCM and the fuse box are and see if there is any evidence of WATER...

Richard A. Snitzer

There is NO evidence of water or even condensation.

Richard A. Snitzer

- Bought car from Penn. Dealer in the fall, no codes related to dash, no dash issues (stuff like outside temp sensor and
seats switch stuff I told you)
- Car mostly sat that winter (2010) with crap weather while I worked on it here and there in NY. When I started it mid winter
just to run it had the dash issues with the forward gages only, no other issues at all.
- I apparently had read a bunch of stuff on these forums and thought it might be the ignitions switch. A guy on line said if I was putting in the i-pod dock I might as well clean the switch contacts.
- Taking out the dash center and right panel for the i-pod dock I pulled the ignitions switch and played with the contacts as the threads on the internet said. FWIW , you have that old switch now which was sanded and filed to make better contact , it did not help at all.
- I got a new A/C Delco switch and put that in. It worked more times than not but still the dash lighting was out sometimes. Tested the battery like maybe 12 times and also charged it many times (I did not have the batt maintainer at this point)
- Even though the batt tested well at static conditions someone at the time said to swap a battery in. Since I had not bought the existing batt I just went out and got a new one.
- No problems after that for maybe 2 years give or take a couple months.
- Somewhere during 2013 the dash started to go dark again at times. No other issues that we could find same as before.
- 2013 I bought another batt and also added the batt maintainer. No problems after that at all.
- 2015 after I got the car inspected I figured I was keeping it this winter and saw it was again 2 years and just changed the batt even though I had no symptoms at the time.

So the switch in the box is the old switch which has been filed and cleaned but it did not make any difference. Also , the job I did on that old switch was not so great. The switch in the dash now is what came in that box and should have very little time and cycles on it at this point.

Bill Curlee

You "MOST LIKELY" have a corrupted Serial Data Bus. There are THREE things that commonly cause this issue.

They are (In NO order for cause) LDCM, RDCM and the Seat Module!

The NEXT time this happens, just for $hits-and-grins",,, OPEN both doors, Grab the rubber accordion tube between the door and door frame, and SHAKE THE HELL OUT OF IT. See if that changes the indications.

I can hear the thoughts in your head, (" What the hell is that guy trying to accomplish??? )

The SIX wire door power connector that is located in the hole inside the door A Pillar can have damaged (spread apart) female pins. The male and female pins make poor contact and cause the door control modules to TURN ON AND OFF RAPIDLY and that corrupts the serial data buss. Thus the VERY STRANGE INDICATIONS.

It can also happen to the Seat Module Connector but not as often as the door connectors.

So,,,, If I were to be a betting man, I would say that is your issue.

You can look to the lefty of the BCM in the passengers foot well and find the two Serial Data Bus STAR CONNECTORS. Find the one with FOUR wires. Pop the TOP of that connector off and that will remove the shorting bus bar. That isolates the LDCM, RDCM and the SCM from the rest of the modules. If the OFFENDING serial data bus corrupter was on either of those modules, the weird symptoms will go away.

If you read the DTC and see a bunch of NO COMMS, you know that you have a serial data buss issue.

Like previously stated, a WET/ DAMP BCM can also cause similar issues.

BC

Richard A. Snitzer

Bill, Mr. Sam:

I shook the accordian at the driver's door. Nothing happened. Went to the passenger floor board and "jiggled" the wires for 3-5 seconds and stopped. Paused, with the car running in neutral and emergency brake on, and a few seconds later the gauges came on. Coincidence? I don't know.

Here are the codes:

10 PCM
P1575 H

99 HVAC
U1096 H
U1160 H
B0361 HC