IMPORTANT ELECTRICAL INFORMATION (Long!)
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Joined: Sep 2013
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From: Cape Coral, Florida
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,412
Likes: 3,964
From: Cape Coral, Florida
1st Gear
Joined: May 2019
Posts: 1
Likes: 0
Corvette C5 1998 error
Hey
I have a Corvette C5 1998, that gives me alot of error codes i hope someone could help me with.
Everytime for 2 years when i start the engine i hear a annoying sound in the speaker.....oh yes grounds most clean i did that, and after that i hear just little sound....and the abs traction control fuel error message stop to come.
I got my Corvette a new paint work, and when i get it the sound came again quite loud. I go crazy...dont think its fun to drive anymore.
Now i was out for a ride, no ground sound at all fantastic.
But after a little time ABS traction control light come service needed. I know i can reset it, but then the computer get stucked...(never happen before).
I check the failure message now and its alot its
28-Tcs c1227 H
C1255h
40-bcm
B0502 h c
B0507 h c
B2482 h c
B2527 hc
B2592 h
B2723 h
A0-LDCM
B2282 h
B2284 h
U1064 h
A1-rdcm
B2283 h
B2285 h
U1064 h
B0-rfa
C2120 h
I read about fix the electric unit but then u should have fault message C1214 i that one i dont have, but i have all the rest haha so please tell me what to do now.
thanks for your time and help
best regards
Robin
I have a Corvette C5 1998, that gives me alot of error codes i hope someone could help me with.
Everytime for 2 years when i start the engine i hear a annoying sound in the speaker.....oh yes grounds most clean i did that, and after that i hear just little sound....and the abs traction control fuel error message stop to come.
I got my Corvette a new paint work, and when i get it the sound came again quite loud. I go crazy...dont think its fun to drive anymore.
Now i was out for a ride, no ground sound at all fantastic.
But after a little time ABS traction control light come service needed. I know i can reset it, but then the computer get stucked...(never happen before).
I check the failure message now and its alot its
28-Tcs c1227 H
C1255h
40-bcm
B0502 h c
B0507 h c
B2482 h c
B2527 hc
B2592 h
B2723 h
A0-LDCM
B2282 h
B2284 h
U1064 h
A1-rdcm
B2283 h
B2285 h
U1064 h
B0-rfa
C2120 h
I read about fix the electric unit but then u should have fault message C1214 i that one i dont have, but i have all the rest haha so please tell me what to do now.
thanks for your time and help
best regards
Robin
1st Gear
Joined: May 2019
Posts: 1
Likes: 0
Many of you have asked me for help on solving electrical problems and I thought this would be VERY interesting!
My 98 coupe would get the infamous "REDUCED ENGINE POWER", "TRACTION CONTROL FAILURE" and a host of random failure codes. After many, many hours of troubleshooting, replacing the BCM and TAC module, I solved most of the driveability issues. Still getting the random DTC failure codes, I thought that I may be having ground issues. Back in June I cleaned ALL of the chassis grounds and the car virtually stopped throwing the "RANDOM" DTC failure codes. Just moving the wires in the chassis ground connector was enough to change the indications and make the issues stop happening.
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:
Attachment 48174127
Attachment 48174128
PLEASE let me know if you have any questions. NOTE! All of the pictures that I have of C5 Grounds have been posted on or in this post.
Bill Curlee
updated 02 March 06
My 98 coupe would get the infamous "REDUCED ENGINE POWER", "TRACTION CONTROL FAILURE" and a host of random failure codes. After many, many hours of troubleshooting, replacing the BCM and TAC module, I solved most of the driveability issues. Still getting the random DTC failure codes, I thought that I may be having ground issues. Back in June I cleaned ALL of the chassis grounds and the car virtually stopped throwing the "RANDOM" DTC failure codes. Just moving the wires in the chassis ground connector was enough to change the indications and make the issues stop happening.
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:
Attachment 48174127
Attachment 48174128
PLEASE let me know if you have any questions. NOTE! All of the pictures that I have of C5 Grounds have been posted on or in this post.
Bill Curlee
updated 02 March 06
We have C5 in Ireland and when driving, windows fail and dash lights fail and traction control light comes and then
in a half hour/ hour it all returns to normal...
Any idea's what to look for?
Thanks in advance
Eddie
Racer
Joined: Jul 2012
Posts: 266
Likes: 6
From: winnipeg manitoba
no fuel pressure
well i think i fixed it
so just a quick update after winter storage (live in winnipeg Canada Brrrrrr) went to start for first time check all fluids primed for oil pressure and then went to start
and it did but just for a short burst spit and sputter and then nothing so started process of tracking down cause first step go to corvette forum for help and to see if
anybody having same problem tons of info cleaned all grounds checked for shorts and so on i must also mention that the car has a sts twin turbo kit installed I purchased the car
like this
ok so after doing all the checks for electrical checked for fuel pressure at the rail and there was nothing so I thought fuel pump (ohhhh noooooo) was not looking forward to that
my garage is so tight i have to step outside to change my mind so dreading this job but before committing to the task just went over everything again and just for giggles started
tracking down electrical there was power at the fuse box relay was good went to driver rear wheel well and no power to the pump so traced back lines to BAP dissembled
the boost a pump looking for bad wires or short and low and behold hiding underneath completely out of view a 30amp fuse that had popped so replaced it and viola (its ALIVE)
remounted BAP and rearranged fuse holder for better access
back up and running just cleaning it up and will be driving by weekend
thank you to c5 Diag for help and recommendations and to Bill Curlee for all the info thats on the forum
thank you
so just a quick update after winter storage (live in winnipeg Canada Brrrrrr) went to start for first time check all fluids primed for oil pressure and then went to start
and it did but just for a short burst spit and sputter and then nothing so started process of tracking down cause first step go to corvette forum for help and to see if
anybody having same problem tons of info cleaned all grounds checked for shorts and so on i must also mention that the car has a sts twin turbo kit installed I purchased the car
like this
ok so after doing all the checks for electrical checked for fuel pressure at the rail and there was nothing so I thought fuel pump (ohhhh noooooo) was not looking forward to that
my garage is so tight i have to step outside to change my mind so dreading this job but before committing to the task just went over everything again and just for giggles started
tracking down electrical there was power at the fuse box relay was good went to driver rear wheel well and no power to the pump so traced back lines to BAP dissembled
the boost a pump looking for bad wires or short and low and behold hiding underneath completely out of view a 30amp fuse that had popped so replaced it and viola (its ALIVE)
remounted BAP and rearranged fuse holder for better access
back up and running just cleaning it up and will be driving by weekend
thank you to c5 Diag for help and recommendations and to Bill Curlee for all the info thats on the forum
thank you
Le Mans Master
Joined: Dec 2006
Posts: 7,251
Likes: 16
From: Phoenix Arizona
well i think i fixed it
so just a quick update after winter storage (live in winnipeg Canada Brrrrrr) went to start for first time check all fluids primed for oil pressure and then went to start
and it did but just for a short burst spit and sputter and then nothing so started process of tracking down cause first step go to corvette forum for help and to see if
anybody having same problem tons of info cleaned all grounds checked for shorts and so on i must also mention that the car has a sts twin turbo kit installed I purchased the car
like this
ok so after doing all the checks for electrical checked for fuel pressure at the rail and there was nothing so I thought fuel pump (ohhhh noooooo) was not looking forward to that
my garage is so tight i have to step outside to change my mind so dreading this job but before committing to the task just went over everything again and just for giggles started
tracking down electrical there was power at the fuse box relay was good went to driver rear wheel well and no power to the pump so traced back lines to BAP dissembled
the boost a pump looking for bad wires or short and low and behold hiding underneath completely out of view a 30amp fuse that had popped so replaced it and viola (its ALIVE)
remounted BAP and rearranged fuse holder for better access
back up and running just cleaning it up and will be driving by weekend
thank you to c5 Diag for help and recommendations and to Bill Curlee for all the info thats on the forum
thank you
so just a quick update after winter storage (live in winnipeg Canada Brrrrrr) went to start for first time check all fluids primed for oil pressure and then went to start
and it did but just for a short burst spit and sputter and then nothing so started process of tracking down cause first step go to corvette forum for help and to see if
anybody having same problem tons of info cleaned all grounds checked for shorts and so on i must also mention that the car has a sts twin turbo kit installed I purchased the car
like this
ok so after doing all the checks for electrical checked for fuel pressure at the rail and there was nothing so I thought fuel pump (ohhhh noooooo) was not looking forward to that
my garage is so tight i have to step outside to change my mind so dreading this job but before committing to the task just went over everything again and just for giggles started
tracking down electrical there was power at the fuse box relay was good went to driver rear wheel well and no power to the pump so traced back lines to BAP dissembled
the boost a pump looking for bad wires or short and low and behold hiding underneath completely out of view a 30amp fuse that had popped so replaced it and viola (its ALIVE)
remounted BAP and rearranged fuse holder for better access
back up and running just cleaning it up and will be driving by weekend
thank you to c5 Diag for help and recommendations and to Bill Curlee for all the info thats on the forum
thank you
Where exactly was that 30 amp fuse hiding? what was it underneath? Thanks! 
Racer
Joined: Jul 2012
Posts: 266
Likes: 6
From: winnipeg manitoba
the way the bap was mounted in the battery bay jts was underneath the bap (boost a pump) and as we know theirs not a lot of room in there
in the future i will relocating it to the rear everything iv read indicates they are happier there also out of the engine bay heat
in the future i will relocating it to the rear everything iv read indicates they are happier there also out of the engine bay heat
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Burning Brakes
Joined: Nov 2011
Posts: 1,037
Likes: 120
Another electrical problem tip, which the manual does NOT address...
The manual says (in two places) to adjust the dash lights from low to bright by turning the dash light control **** all the way to the right/clockwise to have the brightest dash lights. It says nothing about a click/indent at the end of that full turn on the ****. Turning full clockwise turns on your floor lights and map lights and since they are on, the BCM thinks the DCMs (door control modules) also need power because the BCM thinks the doors are open which also turns those lights on.
So when adjusting the dash lights, never turn and leave your dash light control **** turned past the click/indent, or all the way clockwise - to the right.
Go full right and stop turning before hitting the click/indent so that the map and floor lights are not left on when you park the car.
That will drain a battery pretty quick.
Don't ask me why I know!
The manual says (in two places) to adjust the dash lights from low to bright by turning the dash light control **** all the way to the right/clockwise to have the brightest dash lights. It says nothing about a click/indent at the end of that full turn on the ****. Turning full clockwise turns on your floor lights and map lights and since they are on, the BCM thinks the DCMs (door control modules) also need power because the BCM thinks the doors are open which also turns those lights on.
So when adjusting the dash lights, never turn and leave your dash light control **** turned past the click/indent, or all the way clockwise - to the right.
Go full right and stop turning before hitting the click/indent so that the map and floor lights are not left on when you park the car.
That will drain a battery pretty quick.
Don't ask me why I know!
I am incredibly grateful to this thread with all the Bill Curlee tips and your words of wisdom.
To solve today's problem was like getting control of my day again.
Thank you
8th Gear
Joined: Jul 2011
Posts: 8
Likes: 0
Solved two problems!! Thanks!
First I had the ground plug problems. Had dealer and other shop check it out, No success. Saw your posts on the ground plugs and fixed those. No problems for about six months. Then started getting the random no start with dimming dash lights. Your suggestion of the ignition switch was right on.Just got that installed and it has started about a dozen times with no problems. Thanks for the info. Terry Cole
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
BC
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Have someone watch the tail lights and you rapidly rotate the multifunction switch and see if the tail lights and or the headlights have any life. That switch has been known to fail. Also rapidly engage and turn off the emergency light flasher and see if that makes any difference in the tail lights,
Instructor
Joined: Aug 2015
Posts: 178
Likes: 15
Bill,
Is it possible (highly likely) that a bad ground is what is causing my problem starting on my C5 convertible? Intermittently when turning on key to start nothing happens. No start, no solenoid click, nothing. In fact the dash goes blank. The dash does its thing when the key is inserted and even works in the run position, but the start mode is where the failure occurs. When it was first occurred it was towed in and the GM dealership said it was bad ignition switch. They replaced switch but the problem came back in less than 6 months. Past their warranty of course. Then I discovered that if I turned the key multiple times (6-12 or more), eventually it would catch and start. I've been keeping a log of when and where and what time of day and whether on incline or level, in sun or not, etc to help with the diagnosis and unfortunately no consensus. So its not repeatable on demand. My non-dealership shop wants to start replacing fuse boxes and circuit boards because they haven't a clue. That's just throwing money away!
Any idea on what to look for and where?
Your feedback would be appreciated.
professor jim B
Is it possible (highly likely) that a bad ground is what is causing my problem starting on my C5 convertible? Intermittently when turning on key to start nothing happens. No start, no solenoid click, nothing. In fact the dash goes blank. The dash does its thing when the key is inserted and even works in the run position, but the start mode is where the failure occurs. When it was first occurred it was towed in and the GM dealership said it was bad ignition switch. They replaced switch but the problem came back in less than 6 months. Past their warranty of course. Then I discovered that if I turned the key multiple times (6-12 or more), eventually it would catch and start. I've been keeping a log of when and where and what time of day and whether on incline or level, in sun or not, etc to help with the diagnosis and unfortunately no consensus. So its not repeatable on demand. My non-dealership shop wants to start replacing fuse boxes and circuit boards because they haven't a clue. That's just throwing money away!
Any idea on what to look for and where?
Your feedback would be appreciated.
professor jim B
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,412
Likes: 3,964
From: Cape Coral, Florida
That’s what I had to do when my ignition switch started to fail...had to turn the key multiple times to get it to start...do this...on your DIC select voltage and see what it reads when you turn the key to try to start the car...when I selected that I saw 8 volts or so on the DIC...I knew in one second it was the switch !!...don’t know your mechanical aptitude but I can have you do a check with a multimeter !!
Instructor
Joined: Aug 2015
Posts: 178
Likes: 15
That’s what I had to do when my ignition switch started to fail...had to turn the key multiple times to get it to start...do this...on your DIC select voltage and see what it reads when you turn the key to try to start the car...when I selected that I saw 8 volts or so on the DIC...I knew in one second it was the switch !!...don’t know your mechanical aptitude but I can have you do a check with a multimeter !!
If the voltage is 12 V, what do they look for next?
Mahalo (Hawaiian for many thanks) for the quick response.
professor jim B
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
Jim
Before you spend any more money, the next time that it wont crank, you need to WHACK the starter, See if that changes the failure mode. It sounds like you have a starter solenoid failure. They stick and do what yours is doing. If you have someone HOLD the key in the crank position and whack the starter,,,, if the solenoid is the issue, it will crank. You could also have a loose and dirty connection on the solenoid. That will do the same thing.
If you have a MN6/MN12,,, If you HOLD the key in the crank position and pump the clutch on and off the firewall safety switch, you should hear the Theft Deterrent Relay in the passengers foot well CLICK each time you make and break the switch.
If you have an A4, do the same but shift the car out of park and back in to get the relay to click
That will tell you that the ignition switch is working at least for that function.
Before you spend any more money, the next time that it wont crank, you need to WHACK the starter, See if that changes the failure mode. It sounds like you have a starter solenoid failure. They stick and do what yours is doing. If you have someone HOLD the key in the crank position and whack the starter,,,, if the solenoid is the issue, it will crank. You could also have a loose and dirty connection on the solenoid. That will do the same thing.
If you have a MN6/MN12,,, If you HOLD the key in the crank position and pump the clutch on and off the firewall safety switch, you should hear the Theft Deterrent Relay in the passengers foot well CLICK each time you make and break the switch.
If you have an A4, do the same but shift the car out of park and back in to get the relay to click
That will tell you that the ignition switch is working at least for that function.
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,412
Likes: 3,964
From: Cape Coral, Florida
Just have them check the positive battery connection at the starter solenoid and also the negative ground connection that goes to the engine block !!...I understand Mahalo and started to learn to speak Hawaiian years ago...been there too many times to count and was on the Big Island in May 2018 staying at Volcanoes National Park and left to go up to Kona the day before the S$$T hit the fan there...LOL !!...also a big fan of slack key !!
i lā maikaʻi,
Rob
i lā maikaʻi,
Rob