IMPORTANT ELECTRICAL INFORMATION (Long!)
Burning Brakes
Joined: Apr 2004
Posts: 786
Likes: 46
From: Tucson, AZ
Bill, thanks for the response. For codes I cleared them, then started the car and read mostly U1xxxH, 1 U1160HC, and NO COMM for RDCM (below is the list). NO COMM may point to a SCM issue? I was pressing on the seat when pulling the accelerator pedal unit.
BCM: U1255H, U1096H, U1016H
SDM: U1064H
IPC: U1160HC, U1176H
HVAC: U1064H, U1096H, U1160H, U1255H, B0367H
RDCM:NO COMM
SCM: U1300H, U1255H, U1160H, U1016H, U1064H
Removing the buss bar will keep the modules operational… they just loose communication between themselves and the DIC?
EDIT: I disconnected the bus bar and the DIC freaky out did not occur, but no power windows. I connected it while car was running and it freaked out. After turning the car off and restarted it has been working fine since with comm restored to the RDCM. No comm codes either. Hmmmm
BCM: U1255H, U1096H, U1016H
SDM: U1064H
IPC: U1160HC, U1176H
HVAC: U1064H, U1096H, U1160H, U1255H, B0367H
RDCM:NO COMM
SCM: U1300H, U1255H, U1160H, U1016H, U1064H
Removing the buss bar will keep the modules operational… they just loose communication between themselves and the DIC?
EDIT: I disconnected the bus bar and the DIC freaky out did not occur, but no power windows. I connected it while car was running and it freaked out. After turning the car off and restarted it has been working fine since with comm restored to the RDCM. No comm codes either. Hmmmm
Last edited by Joshboody; Jun 29, 2014 at 09:03 PM.
Intermediate
Joined: Jan 2013
Posts: 35
Likes: 0
From: San Tan Arizona
Check Voltages
[QUOTE=Bill Curlee;1587241577]Jimmy
Here is an Alternator Schematic. Start bt checking voltages on the small connector on the alt. Where it goes to the starter or battery, you should see full battery voltage to ground. You also nee to see the GEN TURN ON signal from the PCM.
If you have all that, it should work.
Hello Bill,
Here is what i have for voltages.
With Car Off
Battery = 12.3v
Alt Nut to Gnd (Nut on back of Alternator) = 12.3v
Alt Red wire to Gnd (Black connector into top of alternator) =12.3v , also unplugged connector and have 12.3v.
Alt Other red wire I believe (c2) on schematic 0v
With Car on
Battery = 11.84v
Alt Red wire to Gnd (Black connector into top of alternator) =11.88v , also unplugged connector and have 11.8v.
Alt other red wire (c2) 9.88v when unplugged from alternator. Tried checking voltage with connector plugged in but could not get safety clip inside very good so I unplugged and checked.
Also tried clearing out codes. Just reset key and PCM - P0622 HC (Generator Field/F terminal circuit) appears. I also get HVAC-B0333 HC (Air temp circuit), but I believe that's from the new cold air intake installed.
Does this help, not sure where to go from here.
Jimmy
Here is an Alternator Schematic. Start bt checking voltages on the small connector on the alt. Where it goes to the starter or battery, you should see full battery voltage to ground. You also nee to see the GEN TURN ON signal from the PCM.
If you have all that, it should work.
Hello Bill,
Here is what i have for voltages.
With Car Off
Battery = 12.3v
Alt Nut to Gnd (Nut on back of Alternator) = 12.3v
Alt Red wire to Gnd (Black connector into top of alternator) =12.3v , also unplugged connector and have 12.3v.
Alt Other red wire I believe (c2) on schematic 0v
With Car on
Battery = 11.84v
Alt Red wire to Gnd (Black connector into top of alternator) =11.88v , also unplugged connector and have 11.8v.
Alt other red wire (c2) 9.88v when unplugged from alternator. Tried checking voltage with connector plugged in but could not get safety clip inside very good so I unplugged and checked.
Also tried clearing out codes. Just reset key and PCM - P0622 HC (Generator Field/F terminal circuit) appears. I also get HVAC-B0333 HC (Air temp circuit), but I believe that's from the new cold air intake installed.
Does this help, not sure where to go from here.
Jimmy
Advanced
Joined: Apr 2014
Posts: 52
Likes: 3
From: Newnan GA
turn signal issues
I have a 2000 vert , 6 speed manual. I started getting a hyper flash on the right turn signal. I repaced the rear bulbs ( front worked). When I use the turn signal frequently it works periodically, but not for very long. Since I was still getting the hyper flash I purchased the hyper flash bypass cable. Hyper flash has gone away, but the rear turn signal works sporadically. Sometimes when it works it blinks a few times and then stops. The flashers work. I even switched the left and right bulbs, no change.
Any thoughts?
I appreciate all of rhe information on the forum!
Any thoughts?
I appreciate all of rhe information on the forum!
Intermediate
Joined: Jan 2013
Posts: 35
Likes: 0
From: San Tan Arizona
Still having issues with Charging voltage
Hello Bill,
I just replace my starter with a new starter still have same issue where if I rev the car up to about 4500 rpm the alternator will charge and it goes to 14.2V it starts with 11.88V. Also gives system charge error on display at first.So far I replace battery, alternator twice, and starter. I also added extra ground to alternatorand cleaned all the grounds. I have all the data on the thread earlier. Do you know anything else that it could be, also whats weird is if I drive the car a while it gets hotter and then when I restart the car it goes right to 14.2 volts, I do not have to rev the car.
Thanks,
Jimmy
I just replace my starter with a new starter still have same issue where if I rev the car up to about 4500 rpm the alternator will charge and it goes to 14.2V it starts with 11.88V. Also gives system charge error on display at first.So far I replace battery, alternator twice, and starter. I also added extra ground to alternatorand cleaned all the grounds. I have all the data on the thread earlier. Do you know anything else that it could be, also whats weird is if I drive the car a while it gets hotter and then when I restart the car it goes right to 14.2 volts, I do not have to rev the car.
Thanks,
Jimmy
Team Owner
Joined: May 2006
Posts: 21,472
Likes: 356
From: Palmdale, Ca----- 2009 Cyber Gray 4LT A6 F55 452 RWHP 422 RWTQ- RIP 1998 C5 734 RWHP & 585 RWTQ-----
Hello Bill,
I just replace my starter with a new starter still have same issue where if I rev the car up to about 4500 rpm the alternator will charge and it goes to 14.2V it starts with 11.88V. Also gives system charge error on display at first.So far I replace battery, alternator twice, and starter. I also added extra ground to alternatorand cleaned all the grounds. I have all the data on the thread earlier. Do you know anything else that it could be, also whats weird is if I drive the car a while it gets hotter and then when I restart the car it goes right to 14.2 volts, I do not have to rev the car.
Thanks,
Jimmy
I just replace my starter with a new starter still have same issue where if I rev the car up to about 4500 rpm the alternator will charge and it goes to 14.2V it starts with 11.88V. Also gives system charge error on display at first.So far I replace battery, alternator twice, and starter. I also added extra ground to alternatorand cleaned all the grounds. I have all the data on the thread earlier. Do you know anything else that it could be, also whats weird is if I drive the car a while it gets hotter and then when I restart the car it goes right to 14.2 volts, I do not have to rev the car.
Thanks,
Jimmy
Maybe something like this will help!
Perhaps there is an issue with the actual wiring from the Alt/Batt/Strtr etc.
Thanks,Matt
Intermediate
Joined: Jan 2013
Posts: 35
Likes: 0
From: San Tan Arizona
Thanks for info Matt
I have the wiring exactly like the schematic that Bill attached to the thread. I have not changed any of the wiring from when it was working. Maybe alternator is not getting the correct signal from the computer. Not sure how to check the wiring that goes into the Alternator (the two with fuse-able links from the Starter I am getting the battery voltage). Also I seen on forum it could be ignition switch, but the car starts fine. I checked the both fuse-able links from starter to alternator and they both are good .2ohms.
Thanks,
Jimmy
Thanks,
Jimmy
Heel & Toe
Joined: Jun 2013
Posts: 24
Likes: 1
From: Phila PA
Ground Connection Chart
Anyone have list or chart that shows which "ground" connections (101,102,103, etc) that corresponds to a specific issue or code displayed on the DIC? It would save time knowing which connection to look at first rather than all of them. Thanks
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,396
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
THERE SURE IS! Its in the service manual and it details every ground connection and exactly what connects to it. There are like 3-4 pages of ground & splice packs and 3-4 pages of power / fuse schematics.
Recommend spending the cash for such an invaluable treasure of C5 knowledge:
My ESI is not working or I would post the schematics
Bill
Recommend spending the cash for such an invaluable treasure of C5 knowledge:
My ESI is not working or I would post the schematics
Bill
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Cruising
Joined: Mar 2014
Posts: 11
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:
PLEASE let me know if you have any questions.
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:
PLEASE let me know if you have any questions.
Bill Curlee
updated 02 March 06
Bill,
I have a 2002 Convertible and would like to check and clean all of my ground points since they may be giving me warning light messages. Are all ground points accessed from outside the car from underneath or inside the engine bay and none are accessed from inside the cars interior or which do I need to remove interior panels to get at? How much is a service manual worth, where can I get it and will it show exactly how to safely remove items such as steering columns, seats etc so not to disturb air bag systems and other important vehicle safety systems?
My real issue here is that I get regular 1287 codes and sometimes 1288 codes which leads me to believe I need to replace the SWPS. I have the interior apart to do this since I had several other issues I have already repaired but at this point I am a bit concerned that during steering column removal I will set off the air bag unless I know exactly how to turn off the air bag system with simple instructions such as:
1.Remove negative battery cable.
2.Remove fuse # ? and identify location.
3.Remove steering column from the car and replace the SWPS.
4.Replace fuse # ?.
5.Connect negative battery terminal.
Hope this is not too much to ask to get some technical help with this.
Intermediate
Joined: Jan 2013
Posts: 35
Likes: 0
From: San Tan Arizona
Still having issues with Charging voltage
Hello All,
Almost giving up, just not sure what to do next. So far from previous messages, I changed with new alternator twice,starter, put extra ground on alternator, check fusible links (2 wires from starter to alt), made the front grounds into a single outlet, much better contact thanks guys for info, I still get 11.8v until I rev car to 4500 rpm's. When car is hot it will just goto 14.2 volts or rev it up a little then it will start charging. normally only with a cold start its at 11.8v. I ohm all the grounds they seem great (.02 OHMS). I check the main alternator wire and it is good. I even put new battery cables on. If anyone knows of anything else it would help me.
Thanks,
Jimmy
Almost giving up, just not sure what to do next. So far from previous messages, I changed with new alternator twice,starter, put extra ground on alternator, check fusible links (2 wires from starter to alt), made the front grounds into a single outlet, much better contact thanks guys for info, I still get 11.8v until I rev car to 4500 rpm's. When car is hot it will just goto 14.2 volts or rev it up a little then it will start charging. normally only with a cold start its at 11.8v. I ohm all the grounds they seem great (.02 OHMS). I check the main alternator wire and it is good. I even put new battery cables on. If anyone knows of anything else it would help me.
Thanks,
Jimmy
Intermediate
Joined: Jan 2013
Posts: 35
Likes: 0
From: San Tan Arizona
Pro
Joined: Aug 2010
Posts: 737
Likes: 23
From: NJ
St. Jude Donor '11-'12
Wow, incredible thread!
My oil temp only shows "low" at all times, including after a heavy track session.
I pulled the plug off the sensor near the oil filter while it was disconnected the gauge still read "low". I jumped it to ground and it still said "low".
This all started after having the clutch, and clutch master cylinder replaced. Car shows no other symptoms. I traced the wire back as far as I could see and it is covered in a plastic wire cover and does not seem to be cut. Any thoughts on where to start?
Should jumping to ground make the gauge red something other than "low" or is that old school stuff?
My oil temp only shows "low" at all times, including after a heavy track session.
I pulled the plug off the sensor near the oil filter while it was disconnected the gauge still read "low". I jumped it to ground and it still said "low".
This all started after having the clutch, and clutch master cylinder replaced. Car shows no other symptoms. I traced the wire back as far as I could see and it is covered in a plastic wire cover and does not seem to be cut. Any thoughts on where to start?
Should jumping to ground make the gauge red something other than "low" or is that old school stuff?
Navigator
Joined: Aug 2014
Posts: 9
Likes: 1
Ok, any ideas?
First, let me say thanks for all of the great information on this thread.
A bit of background. This is my first Vette (well my wife's first).
It is a 2004 with ~40k miles. Everything has been fine with it until very recently.
The first thing that went was the TPM system wouldn't show the air pressure. I reset it several times, but it will just drop out and report an error again after some time frame ranging from a few days to few weeks. This went on for several months until within the past couple of months when it just wouldn't reset.
Then within the space of a week the system started giving me messages on the DIC regarding the ABC, traction control, and stability control. On rare occasion it will flash up message to service the engine soon, but that just goes away.
During this time, there have been 0 impacts to drive-ability of car. It runs fine all the time with no impact.
I found this thread and cleaned the three grounds under the hood. None of them looked very bad, but I cleaned them all up anyway in the hopes it would address it.
Two other items that might or might not be related are the AC suddenly quit, and the external temp reading on console always shows 69 degrees.
The codes I'm showing in the system now after doing the cleaning, getting the tire pressure sensors replaced, and test driving it are as follows. With the engine off if it matters.
And it still reports the same three items every time you start it up, until I clear them from the display.
C1265 H
C1284 HC
C1285 HC
And for the HVAC
B0333HC
B0361H
B0441H
If anyone could give me any thoughts on what to try next short of giving a dealership a blank check it would be greatly appreciated.
Joe
A bit of background. This is my first Vette (well my wife's first).
It is a 2004 with ~40k miles. Everything has been fine with it until very recently.
The first thing that went was the TPM system wouldn't show the air pressure. I reset it several times, but it will just drop out and report an error again after some time frame ranging from a few days to few weeks. This went on for several months until within the past couple of months when it just wouldn't reset.
Then within the space of a week the system started giving me messages on the DIC regarding the ABC, traction control, and stability control. On rare occasion it will flash up message to service the engine soon, but that just goes away.
During this time, there have been 0 impacts to drive-ability of car. It runs fine all the time with no impact.
I found this thread and cleaned the three grounds under the hood. None of them looked very bad, but I cleaned them all up anyway in the hopes it would address it.
Two other items that might or might not be related are the AC suddenly quit, and the external temp reading on console always shows 69 degrees.
The codes I'm showing in the system now after doing the cleaning, getting the tire pressure sensors replaced, and test driving it are as follows. With the engine off if it matters.
And it still reports the same three items every time you start it up, until I clear them from the display.
C1265 H
C1284 HC
C1285 HC
And for the HVAC
B0333HC
B0361H
B0441H
If anyone could give me any thoughts on what to try next short of giving a dealership a blank check it would be greatly appreciated.
Joe
Advanced
Joined: May 2012
Posts: 75
Likes: 2
Thanks folks, this is my second Vette, and I thought the C4 had problems. I've been having alot of these same codes, so I started cleaning the grounds.
I found that G-104 had a weld splatter ball at the frame, and the ground lugs weren't flat to the stud. Someone also changed out 2 of the 3 lugs at that location. Ground the ball off with a dremel and it seems to be working now.
I just started looking for the rest of the grounds now. 103 on the drivers side was slightly bad. Once the heat slows down in Phoenix, I will start cutting off the factory connectors and go with lugs instead.
I found that G-104 had a weld splatter ball at the frame, and the ground lugs weren't flat to the stud. Someone also changed out 2 of the 3 lugs at that location. Ground the ball off with a dremel and it seems to be working now.
I just started looking for the rest of the grounds now. 103 on the drivers side was slightly bad. Once the heat slows down in Phoenix, I will start cutting off the factory connectors and go with lugs instead.
Thread Starter
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,396
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
If it were me, I would service (CLEAN ) the contact inside the ignition switch.
C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
BC
C5 ignition Switch repair - http://forums.corvetteforum.com/c5-t...ch-repair.html
BC
Advanced
Joined: May 2012
Posts: 75
Likes: 2
Thanks Bill, for fuse #16, the PCM fuse, I am only getting 7.3 volts when it doesn't start. When that fuse is above 12V, it starts every time. And is really intermittent. My mechanic is starting to say the ignition switch as well.
