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I'm having an intermittent electrical problem with my C5, I'm hoping someone can help me figure it out. This problem only came about a few weeks ago and seems to be getting worse quickly. The dash illuminates when I put the key in ACC and I can open the windows in ACC but the display where it says "CORVETTE" doesn't light up and then when I start the car, the dash goes dark, the gauges are dead, I can't open the window, the radio and AC don't work. Other than that the car runs fine with all power and no warning lights. Here is a list of stuff we've done so far:
Battery out and tested fine
All battery connections cleaned
Grounding below battery removed and cleaned
Both ground points and plugs near headlight buckets removed and cleaned
Starter solenoid connections tightened
Ignition switch replaced with new Delco switch
We are really stumped, any help would be greatly appreciated!
Please pull your dash DIC codes and let's see what shows up. Let us know if you don't know how.
Thanks so much for replying:
I would love to pull the codes but I can't because the display won't light.
I did pull them on 8/8 when this started and the next time I started the car everything worked. At that point I got some history codes B2285H and P1575HC.
Is there some other way of pulling them without the display?
I would love to pull the codes but I can't because the display won't light.
I did pull them on 8/8 when this started and the next time I started the car everything worked. At that point I got some history codes B2285H and P1575HC.
Is there some other way of pulling them without the display?
A plug-in OBD2 code reader will do the trick. Autozone/Oreilly will do it for free.
I would love to pull the codes but I can't because the display won't light.
I did pull them on 8/8 when this started and the next time I started the car everything worked. At that point I got some history codes B2285H and P1575HC.
Is there some other way of pulling them without the display?
If his problem was emissions related that would do the trick.
The readers that parts stores have can ONLY read standardized emissions codes. They cannot read the C5 (or any other car for that matter) vehicle specific codes. You need a specialized reader that has the capability to plug in modules that contain the diagnostics reading capability of specific cars. Those are far more expensive than parts store care to invest for free services.
OP's problem as described is not emissions related,,,,,,,,,,,,
Not to hijack the threat 'cause the OP has his codes...but I have an Actron 9180 ($69 on that auction site), and it speaks very well to the Vette as well as the Wife's Subaru. Pulls all the OBD2 data, tests O2 sensors and diagnostic codes. So what you are telling me is that it will only pull emission codes like the 0420 the Suby is currently throwing and none of the others?
It does NOT have the ability to pull vehicle specific codes. ONLY the standardized emissions codes that the EPA has established across all vehicles sold in the US. Standardized meaning those codes that could be tested for by the emissions testing sites in most states that require emissions testing.
Codes related to TCS or BCM and most PCM codes etc will NOT be seen/reported by the hand held tester. Those are not required to be standardized and do in fact vary from brand to brand of vehicle and even across models within a brand.
There are no codes that begin with V. They must be U1096 and U1160. But it is important to know which sensor the two Uxxxx codes were listed. Ie 10 - PCM or 28 - TCS or 40 - BCM etc.
B2527 is the horn relay circuit. B0361 and B0441 are HVAC actuator issues. NONE of those 3 relate to the symptoms you posted.
Unfortunately I didn't realize I had to write down the first part and since then the battery was disconnected and the codes are gone. Hooked the car directly up to the charger and thought the issue was fixed (i.e., the battery) but after the 4th turn of the key had the same problem again.
Checked most all of the grounds and they look good.
Do you have a digital multi meter? If so open the hood and measure the voltage across the battery posts with no key in the ignition. Needs to be above 12.5 volts for the electronics in the car to be happy. Car will start with 12.2 volts or less but most of the electronics will NOT be happy if the voltage is 12.55 or less. Most go through diagnostics when the key is turned to the ON position and many will fail diagnostics when the battery voltage is low. Having voltage from the alternator once the car starts is too late.
OK - Battery measures 12.56v
When it was load tested it measured 12.38v with 630CCA
But when we had the battery out and had the car hooked up directly to the battery charger itself, it worked maybe 6 out of 10 times. Wouldn't have worked every time then?
Since you have different results over several starts I would next suspect the ignition switch and whether or not the full battery voltage is reaching the devices to be powered.
Here are 3 links on the C5 ignition switch. If you have a digital multi meter, I would definitely go through the diagnostis steps below:
Yes, we were just thinking it leads back to the ignition switch, but we just put a new one in, I'm not sure if he checked the wiring to the switch though. My husband, who is ready to kill himself, just went to get a new battery anyway but I will tell him about your thoughts on the switch. Any possibility of it being a relay?
I'm on page 71 of Bill Curlee's post about Important Electrical Info, but I haven't found anything that specifically has my issue.
Im having the same intermittent no start condition. I have replaced the ignition switch, ignition lock, the battery and got 2 new keys. Today I accessed the BCM through the passenger footwell and there seems to be a bad connection somewhere. As I was checking the connections the interior light in the passenger footwell was going on and off while I wiggled the harness. I also started getting the charging system fault message on the DIC when it does start. Searching for answers I found lots of people having random electrical issues that was caused by a bad BCM or bad ground. Im going to check all the grounds next then possible buy a used BCM. What sux is my Z is stranded in a parking garage 20 minutes away since last night so troubleshooting it there is not working out so well Getting frustrated but I feel Im getting closer to finding the problem. I mean how many parts are left to replace at this point lol
I just reread the entire thread here and I had forgotten that the ignition switch had been replaced as you stated in post #1.
I would STILL do the voltage measurements from the DIAGNOSIS thread on the above post for the ignition switch assuming you have a digital multi meter and can use it.
The symptoms seem to be pointing to a voltage related issue. Either the switch is causing a voltage drop or the battery is actually not as good as the testing indicated it is. That is where I would be focusing. Battery and voltage related issues can cause some very strange issues for the C5.
One quick test that you can perform is to set the information that is displayed in the DIC to something like oil pressure. Do this with the key on and engine off. The turn the key off. Then start the car and see what is displayed in the DIC. If it is NOT the oil pressure (or what ever you chose to set it to) or specifically it is the vehicle mileage, then the voltage on the battery is dropping below threshold level during engine crank that is causing computers to be reset. If the display is what you originally selected it to be then the battery is probably NOT the issue....
Checked the fuses in the diagnosis, all good.
Turned the key and it worked so I was able to pull these codes:
I wonder if one of the modules that is only powered-up with the key in the run position is corrupting the serial bus. You can isolate the modules at the star connectors by the BCM and then jumper them into the circuit one by one to see if one of them is causing the issue. The start connectors are a flat single row connector where a bunch of wires go in one side and a jumper bar plugs in the other side. I'd disconnect the small one first then the longer one if the small one doesn't fix it. If you pull the longer one, you need the BCM and PCM connected as a minimum to make the car start. Then, I'd jumper in the cluster 3rd and the others in whatever order you feel like one by one after that. Here is the schematic showing the star connectors.
Originally Posted by 8VETTE7
Needs to be above 12.5 volts for the electronics in the car to be happy. Car will start with 12.2 volts or less but most of the electronics will NOT be happy if the voltage is 12.55 or less.
I constantly see this posted but find this hard to believe. Many of the electronic modules throw a low voltage code when the voltage drops down to around 8-9V so they're still working at that voltage. It seems to me the car tends to burn-out relays first due to the low voltage.
12.5V vs 12.2V tells you the battery is discharged. Without knowing the quality of the meter, At 12.56V I wouldn't be very concerned about the battery being discharged.
I wonder if one of the modules that is only powered-up with the key in the run position is corrupting the serial bus. You can isolate the modules at the star connectors by the BCM and then jumper them into the circuit one by one to see if one of them is causing the issue. The start connectors are a flat single row connector where a bunch of wires go in one side and a jumper bar plugs in the other side. I'd disconnect the small one first then the longer one if the small one doesn't fix it. If you pull the longer one, you need the BCM and PCM connected as a minimum to make the car start. Then, I'd jumper in the cluster 3rd and the others in whatever order you feel like one by one after that. Here is the schematic showing the star connectors.
I constantly see this posted but find this hard to believe. Many of the electronic modules throw a low voltage code when the voltage drops down to around 8-9V so they're still working at that voltage. It seems to me the car tends to burn-out relays first due to the low voltage.
12.5V vs 12.2V tells you the battery is discharged. Without knowing the quality of the meter, At 12.56V I wouldn't be very concerned about the battery being discharged.
Thanks for this idea, I appreciate all the help...We are done working on the car for tonight because we're tired and disgusted but welcome all ideas! We don't know that much about the electrical system. On the scale of things we're good at, I would put that on the bottom.
That being said, I'm going to try this tomorrow since I get home before my husband does. So just to be sure. I think what you're saying is to disconnect Star Connector 2 .(small one) first and then turn on the key to see if I still get the problem. If the problem is corrected I then need to jump each module to see which one it is?
I'm assuming I leave the key off until I disconnect it?
Where am I making the jump connection? I saw a picture of it opened but it is not clear from the photo?
Do I leave the key in ON position while I'm doing this or shut it off and only turn it back on when the jump is made each time?
So how charged is 12.56V, once you consider that the 100% charged voltage does vary with temperature and that the meter could easily be off 50mV? It's never as simple as a fixed number being the answer.
The top of each of the two connectors, as seen in the last picture, is a set of shorting bars. Referring to the wiring diagram for connector 2, the shorting bars serve to connect points C, D and K to point A. In other words it adds the LH door control module, RH door control module and the Seat control module to the Serial Data Buss.
Removing the shorting bar from connector 2 removes those devices from the serial data buss. If any of those 3 modules is the source of the problem, the problem will be gone once you remove the shorting bar.
If the problem is gone then you need to determine which of the 3 is the cause. To do that you need to provide a jumper wire between point A (purple wire) and the device you want to add back to the serial data buss.
I would remove the shorting bars from connector 2 with the key OFF. Then check to see if the problem is corrected. If corrected, then pick one device to add back and provide a wire between the purple wire (point A) and the selected device. I would add that wire with the key OFF. Then once the connection is securely made check to see if the problem has reocurred. If it has not reocurred then turn the key OFF and move the jumper wire to the next device to be tested. At some point the problem will hopefully reoccur. When it does then you know what device to focus on.
All 3 devices are common causes of issues on the serial data buss.
While the 3 devices are disconnected you will NOT have control of the door locks, windows, mirrors, seat movement etc. Once you reconnect a device the functions controlled by that device will return.
There are write ups for working with each of the 3 devices that can be provided once you identify the problem device.
I have another question, it may be stupid. If I do have to go to the bigger connector, what am I connecting the jumper line to? Am I still connecting it to the purple wire in the small connector or to the Lt Grn in the large connector?
I'm sorry for all these stupid questions, I just don't want to cause damage to anything.
There should be an appearance of the purple wire in BOTH connectors. You can connect to either appearance of the purple wire. If you look at the first picture below the wiring diagram you can see that wire in both connectors. Right most connector in the picture is the small one.
If you have to go to the large connector you will need both the BCM and the PCM connected to the purple wire at all times be able to start the car.
In the diagram that is point M (dark blue and white wire) and point B (dark green wire).
Without the BCM and PCM being able to talk to one another across the serial data buss, the car is just a bunch of parts that will not start/run.
Thanks! I'll let you know what happens. I'm keeping my fingers crossed!
Thanks! I'll let you know what happens. I'm keeping my fingers crossed!
OMG. So I didn't get home from work as early as I had planned but I had all the instructions and pictures printed out, thanks so much for all the info, made a couple jumper wires, etc. ready to go.
Turned the key and ON it went, and it went, and again. I have now spent the last 3 hours trying to get this stupid thing to fail and it goes on every time. Tugged on the wires, tried every combination of things, moved the seat, opened the door, shut the door, sat in the seat, didn't sit in the seat, blah, blah, blah.
So now it works every time and I have no idea what so ever why.
The only thing that was new was that we put in a new battery yesterday. But yesterday after the new battery was put in, I was still getting the failure occasionally. So I did not expect anything to change today.
Electrical Problems - Please Help
