fixvet

That looks familiar, Don. Mine had 3 badly corroded which caused all my NO COMM issues. All's well that ends well!

Edward J. Osterman

Thanks Bill, Great review on ground issues. Curious as I've been without an under hood light for sometime now and suspect a blown fuse but the 2001 owners manual doesn't seem to list a fuse location for that specific application. Any ideas on what it's connected with and the location? Thanks, Ed



I had a chance to speak with some GM C5 Trouble Desk Engineers when I went to Bowling Green KY in April and they pointed out that MANY of the C5 electrical issues can be directly linked to chassis ground problems. The engineer even went as far as to recommending that I chop off the factory under hood chassis ground connectors and combine all of the wires into a single ground lug. Not wanting to just LOP off the factory connector, I took a chance and disassembled one of the ground plug connectors and to my surprise it was indeed full of corroded connections.
I strongly recommend that any C5 owner that has had or who are having electrical issues, examine and clean the chassis ground connectors. This may save you from needlessly replacing expensive electronics modules. Each ground connector can be disassembled and cleaned in about 20 min.

Just cleaning the metal ground connection between the chassis and the plug is only a band aid solution. Now that I look back, when I cleaned my chassis grounds and initially solved my issues, I believe that when the connector is being removed to clean the connection between chassis and the connector, just the wires being moved inside the plug is what changed the indications and made everything work better.
Disassembly of the chassis ground plug and cleaning the contacts inside the connector is the correct method of solving the issue!

I took some pictures of the under hood chassis ground connector and the corrosion that was in it. I cleaned the two connections on the frame rails and the left one was significantly corroded! Taking it apart and cleaning it is a very straight forward procedure and I believe that if you follow this recommendation, you will be on the way to solving the many of the electrical issues.

Here are some detailed pictures of the ground connector and the corrosion that was found inside it!

Picture of under hood Chassis Ground connector G-101



Corrosion inside connector! (You ain't seen nothing yet!)
[IMG][/IMG]

Next three photos are of the corrosion found on the connector terminals!
[IMG][/IMG] [IMG][/IMG] [IMG][/IMG]


Self tapping ground screw and star washer. This is what you will need if the ground stud breaks off during removal!
[IMG][/IMG] [IMG][IMG]

Here are where the chassis ground points are on a C5:









PLEASE let me know if you have any questions.

Bill Curlee

updated 02 March 06[/QUOTE]

portney

I started getting the "ABM triad" yesterday. DTC 1232 indicated, so I read thru the threads, inspected ground wires and harness connector conditions, found no issues with corrosion, etc. I then checked resistance at the wheel speed sensor and checked AC voltage as well, both within tolerance. So I began testing the wiring continuity from the LF WSS to the EBCM and found a discontinuity in one of the wires. Further testing isolated the problem to the 2 1/2 foot long wire which runs from the sensor wire connector mounted just inboard of the brake disc to another connector mounted on the chassis just inside the wheel well.

I called my local Chevy Parts and was informed that a) the part is no longer available thru GM, and b) the 2004 model year was the ONLY year that this short extension was used - all others, according to the parts guy, made a continuous run from the WSS connector to the EBCM harness connector.

I have checked Ebay and can't find one there. I guess I could go to a junk yard. Any other suggestions for locating one? any earlier C5ers out there who can confirm the story aboout this being the only model year with this short 'jumper'?

Bill Curlee

YOUR PARTS GUY MUST BE SMOKING DRUGS.

EVERY C5 from 97 to 04 have a jumper harness on the front sensors. Thats how you are able to turn the wheels left and right.

Call Gene Culley or Patrick @ CULRAG Performance

Here is his latest Forum Sale Post. The contact info is there:

https://www.corvetteforum.com/forums...rformance.html

SilverC54me

Just did the Ignition switch on my brothers 01 coupe. It was suffering from TCS no comm and HVAC no comm. After about a minute the modules would come on line. This occurred on every start up.

The half dozen starts so far have not shown an issue. We will see how it goes over the next couple of days.

There were 3 sets of contacts that were totally black. Cleaned with 000 steel wool and contact cleaner. Bent them a bit to make better contact.

This is the third ignition switch I have done with good results. Bill thanks for posting the info on cleaning the contacts.

Gary

portney

Thanks for the direction. Cultrag now bookmarked, and 'harness extension' is ordered.

chuck1992

My 03 vette was running good but then all the sudden the dash went crazy and started to throw all kinds of codes ex: inappropriate shock, reduce engine power and all the gauges went crazy and went high to max out. I was wondering if anyone has had this issue with there corvette before and was wondering how to fix it and or what to do. I would like to fix it myself and avoid a dealer because it can get expensive and fast any help on this is appreciated. I like to work on my car myself but i don't know where to start ATM please help if more pictures are needed just let me know.

I have some images to go along as well



notice the coolant maxing a 260.








reduce engine power

Bill Curlee

Chuck

This issue (very common) has be covered 400 times. Probably 100 in this post alone.

You either have:

A WET BCM

OR

A damaged/ corrupted or shorted serial data buss. Ususlly caused by the LDCM, RDCM and or seat control module.
Check for a wet BCM first. Look UNDER the carpet

BC

chuck1992

thanks Bill !! how do I check the BCM? I am pretty new to the whole electrical game of the car and wanted to get some directions on how to check and fix the problem. I know how to do a lot of body type work on cars but electrical is new for me. Another question is should I clear the codes on the car to see which ones are happening at the moment and not historical codes from the car? just a little nervous about the whole thing and don't want to mess anything else up worse than it is. sorry if i have to many questions just new to this whole thing and don't want to be the guy who isn't informed properly before tearing apart his car.

Bill Curlee

WET or DAMP BCM ??????

YES or NO ???



YES,,, Clear your DTCs Trust me,,, If theres something wrong,, the DTC will be back

Bill Curlee

AFTER you determine if the BCM and or the carpet around the BCM is or has been wet,, and answer that question,,

Find the two thin connectors to the LEFT of the BCM. Pop the TOP off the one that has FOUR wires and see if the weird things stop happening.









BC

chuck1992

Thanks for the Help Bill! I was wondering if you know where I can get a manual on the car for all the technical kind of stuff I will be starting to look at it tomorrow for the BCM's and getting back to you about the condition.

Bill Curlee

Look in the C5 parts for sale, E-bay, Amazon and if you want NEW,, contact Gene Culley at CULTRAG Performance.

Bill

chuck1992

BIll sorry it took so long I looked up the codes on the dic and all have an H at the end which should mean history correct and that are not current codes or problems with the car? And the other thing I found going through all the codes is the LDCM has no comm. what does that mean? Thanks for your help..

Bill Curlee

Hmmmmmmmm,,,, "H" DTCs do really mean something and serve as a valuable troubleshooting aid (at least for me)

LDCM NO COMMS... Well,,,, Ide say you found part of your issue... remove the door rubber accordion tube,, dissconnect the connectors on the door harness and examine the femail pins.

BC

Ed Glomb

I have a 2003 vette and if the car is not driven the battery will lose its charge. Have had it to several mechanics and no one can figure out why it draws down so fast. Any ideas very frustrating charging the battery every 3 days.

Bill Curlee

ED

How much money have you spent on SEVERAL MECHANICS just so they can say,, "BEATS ME, I have NO idea what causing it!" ????

The VERY first thing that you need to do is actually MEASURE the sleep current draw with a DC AMP METER in series with the NEG battery terminal/cable. Report that number reading..

Bill

NewbieHunter

Hey Bill,

Today when I got into my car I noticed the front windshield was fogged up. This should have been a clear warning that the inside of the car had gotten wet and that the Texas heat had evaporated it. Anyways, the car started up fine and I drove it to the local car wash. After washing the car I got in to start it and it would only turn over. After pulling the codes I am receiving a No Comm on all functions. I realized there was some moisture in the passenger floor board. I spoke with Brett (BlownBlueZ06) and he advised me to check the BCM area. There was some moisture in the area so I removed the BCM and cleaned and dried the board. I cleaned up the remaining moisture in the area and tried to fire it up.... No Comms, reduced engine power, etc etc. Referring to this and other posts, I've tried disconnecting the battery and reconnecting it, verified a good battery, checked the grounds, disconnected the Star 1 terminal to isolate the SCM, RDCM, LDCM... Still No Comm on all functions. I disconnected the Star 2 as well and ran the jumper wire from the PCM to the BCM. Still No Comm on all modules. At this point do you have any suggestions on the next step? I've seen many people have success from doing the ignition switch replacement, but I just wasn't sure if this would be a fix for someone having No Comm on all modules. Any advice is greatly appreciated!

Gene Culley

Thank you for the referral Bill. Your referral points are racking up

Bill Curlee

The BCM is NOT PLAYING!!!!! Check ALL the BCM fuses. It has to have power and ground. There are MULTIPLE BCM FUSES!!!! Check the fuse and use a METER and make sure there is VOLTAGE to chassis ground on each one of the fuses. Some are powered when the ignition is ON.

The BCM MUST be completely DRY!!! NOT damp or wet.

The board inside could still have moisture on it. It will not work properly if it is not DRY!

Also check each BCM connector for moisture!

If he board got wet,, it could have corrosion on it and some of the circuit traces inside could be compromised.

Look for white deposits on the board that short circuits:\





BC