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I checked the connectors under the passenger side carpet and all of them are clean and tight. I also have, new today, the inability for the horn to honk upon lock (did not change this in the DIC) but now that both headlights are working, can drive at night.
These cars certainly do seem to find the “path of least resistance” when there are electrical issues, leading one to believe multiple systems are failing, but I do agree - the comments so far on checking grounds and connections have put me on the right path so far.
For those who are electrical experts, what does it mean when you go to lock the car from the FOB and it just flashes all door lights and clicks a relay back and forth multiple times? Is the RCDLR the next thing to check?
Also, my battery is again at 11.7V after being in the car overnight, but stays above 12 when you charge it with a tender and take the battery out of the car.
I’m willing to believe it’s the aftermarket stereo, just odd how it worked fine for 8 years and even after a head unit swap to another Nav head unit (also aftermarket) the same issues are there. I didn’t try a new RP5-GM11 harness or the factory (OEM) radio yet, work had me pretty swamped last week.
FWIW a damned defective OnStar module was reported source of power drain.
Apparently thing wasn't turning off as it was supposed to.
IF NOT using OnStar, pull the fuse.
Eliminates one possible issue.
Appreciate all the help fellow forum members. Been super busy with work and haven’t done much except clean some grounds, which seems to be helping (at least things are going in the right direction).
Since I regularly take the car on trips where services are limited, such as through rural Nebraska, would it be a good idea to carry some sort of basic tools (such as a voltmeter) in case these issues crop up again? Also thinking of getting a decent code reader.
With the number of issues cleaning the grounds have solved, I think this should be regular practice every 160-200k miles even on C6’s that aren’t experiencing issues. If anything, I will probably have to do this again at 340-360k miles anyways.
Speaking of, what are some things that should be done at or before 200k? I don’t have a 200k service in my manual (ends at 150k), and want to keep up on the maintenance so the car can go the distance. Rear end flush? I’m getting close to 200k and want to have a reliable, dependable car.
I have a 2009 C6/1LT/auto that has served me well for many years. I am the second owner and have driven the car daily since 2014 in which it had 68k miles. The car has around 170k miles now and has developed some strange electrical issues. The car has been to several shops and dealers who have thrown a boatload of parts at the vehicle, only to have the problems return. As of yesterday, the car has experienced:
Entire radio display is dark and will not even provide backlighting to the buttons when the headlights are on.
Navigation head unit is non-functional and even the CD stuck in the stereo refuses to be ejected.
One headlight (usually the driver side) goes out when the Left turn signal is activated.
Map lights and other lights stay on even after leaving the car, but lock/unlocking cures this (sometimes).
I recently took the car on a 800 mile road trip and found the interior lights staying on at rest areas, even after leaving the car and locking with the keyfob. This would stay on after the 20 minute "Retained Accessory Power" feature and remain on until I started the car. Within the past week, the car has experienced:
Alarm going off even after you've unlocked the car with the factory keyfob/remote.
Unable to pair a second keyfob/remote using the procedure in the owner's manual.
Random lights such as tail lights, reverse lamps, and other lights on when parked.
Interior bulbs burning out at random (driver side footrest, DIC buttons, HVAC defrost).
Dealers have been unsuccessful in repairing the car after throwing numerous parts at it. The car has received two alternator replacements (based on this I am assuming #3 is what's in the car), a new fuel pump and fuel pump sending unit (they were diagnosed as bad), multiple Optima Yellowtop batteries (three replacements), and it still drains the battery after sitting for several days. I have to keep the car on a battery tender daily even though it sees 250-450 miles of travel per week, as it's a daily driver.
The car does have an aftermarket stereo in it, installed with a PAC RP5-GM11 interface adapter, but that has been installed since 2014. Just to rule that out, I swapped in a different aftermarket stereo just to eliminate the existing Alpine head unit (in case it had an internal short). I can try putting the OE stereo back in, which would enable the factory XM and OnStar features, but am not sure if the radio is the culprit - if it is, why did it take 8 years to occur (and there are no shorts on the harness, connections were soldered and not crimped).
Today the car showed all of the same electrical issues with the driver side headlight turning off regularly when the turn signals were enabled. Multiple times I would hear relay noises that shouldn't be happening, even after I opened the hood. The fuel pump relay (#55) is very hot to the touch, and the battery isn't charging after a 20 minute drive - when put on a battery tender it showed the battery was depleted. Voltage when sitting is around 12.1-12.3V right after shutting off the engine.
I'm afraid to take this thing back into a shop again and receive thousands of dollars of parts thrown at it and no resolution. The only thing I can think of is try cleaning connectors/grounds, put the factory stereo back in, and then hope I find a decent repair facility that isn't going to play the "keep replacing things until it fixes the problem" game because that's all most shops have done so far.
If you had an excellent condition C6, with only this minor problem, what would you do?
Well the first thing I’d do is scan for codes and see which modules you can and can’t talk too…I’d be looking for some “U” or communication DTC’s…I’d throw a labscope (99.99% of dealerships or repair shops don’t use one) on those comm lines and see what’s happening when all this weirdness starts…with the battery drain do you know how to do a parasitic drain test ??…that may help with a diagnosis..I’ll look at wiring tomorrow and see what I can find with what you have going on…I think you are the 4th person I told not to take their car to a dealership for diagnostics…an auto electric shop in your area may be of better help…where are you located ??
Well the first thing I’d do is scan for codes and see which modules you can and can’t talk too…I’d be looking for some “U” or communication DTC’s…I’d throw a labscope (99.99% of dealerships or repair shops don’t use one) on those comm lines and see what’s happening when all this weirdness starts…with the battery drain do you know how to do a parasitic drain test ??…that may help with a diagnosis..I’ll look at wiring tomorrow and see what I can find with what you have going on…I think you are the 4th person I told not to take their car to a dealership for diagnostics…an auto electric shop in your area may be of better help…where are you located ??
I’m located in Central IL (near Bloomington) but work all over the country. My office is in Minneapolis and I have clients mostly in Michigan so that means regular 800-1000 mile trips when I travel. I don’t have any DTCs, at least ones that OnStar or a cheap Actron code reader can find. But, since the problems are intermittent, I wouldn’t think it would set codes unless a problem came up while driving, which is what originally set the fuel system codes, but those have since gone away along with other electrical issues after cleaning grounds.
Edit: I may have had “Lost Communication with BCM” at one point but the dealer cleared and it has not come back, go figure.
Well here are few diagnosticians in the Chicagoland area and John Thornton is probably one of the top two in the country and is the top instructor in the U.S. as well….check out these guys…Eric Ziegler I’ve heard of…if these 4 guys can’t find it nobody will…I just can’t believe the dealership just erased the “No Comm” with the BCM…if it were me I’d be going down that path with that module !!
There are a total of 12 major ground locations on the C6 Chassis. They are all subject to causing electrical problems when they either loosen or become corroded and create a high resistance.
I have the location of all 12 in a PDF. I'll attach it here. I remember dealing with an electrical problem that came from a loose ground on one of the REAR chassis grounds. So I encourage that all of them be checked.
Last edited by BlindSpot; Sep 24, 2022 at 08:29 AM.
Also, my battery is again at 11.7V after being in the car overnight, but stays above 12 when you charge it with a tender and take the battery out of the car.
.
That's a big drain, something is not right. I'll take another WAG that if you fix the cause of that parasitic drain, you'll fix your other electrical issues.
The good news is: As big as the drain is, it should be fairly easy to find for someone who knows what they're doing. Great idea to take the car to one of the recommended diagnostic guys and give your dealership some time off. Sounds like they have done all they can do at their pay grade.
That's a big drain, something is not right. I'll take another WAG that if you fix the cause of that parasitic drain, you'll fix your other electrical issues.
The good news is: As big as the drain is, it should be fairly easy to find for someone who knows what they're doing. Great idea to take the car to one of the recommended diagnostic guys and give your dealership some time off. Sounds like they have done all they can do at their pay grade.
Thornton is hands down the best out there !!…I attended one of his misfire classes a few years ago and I learned a lot !!
Thornton is hands down the best out there !!…I attended one of his misfire classes a few years ago and I learned a lot !!
Thanks, looking to give him a call. Currently on a 950 mile (round trip) drive and am noticing that the handling is not what it used to be. Car seems difficult to keep straight even after a recent alignment.
Does GM not have service recommendations for 200,000 mile service, 300,000 mile service, etc. for this car? Not sure if I need tie rods, wheels are out of round, or if I need other front end components such as control arms. Wish there were some “replace at XYZ miles” guides which seem to be missing from the manual.
My ‘09 manual just covers stuff like spark plugs and fluid changes, but not much about regular mechanical maintenance (tires and alignment are in the manual, but those seem to be the obvious things to replace).
Since I regularly take the car on trips where services are limited, such as through rural Nebraska, would it be a good idea to carry some sort of basic tools (such as a voltmeter) in case these issues crop up again? Also thinking of getting a decent code reader.
That's always a "must do", second in importance only to a fire extinguisher. WHAT those tools are varies with year of the car - A code reader won't be much help on a C-1, a BFH probably would get less use on a C-6. (altho OP has probably been tempted a few times! ) You can set up a small kit with whatever you want, but absolutely don't lave home without it.
Does GM not have service recommendations for 200,000 mile service, 300,000 mile service, etc. for this car? Not sure if I need tie rods, wheels are out of round, or if I need other front end components such as control arms. Wish there were some “replace at XYZ miles” guides which seem to be missing from the manual.
./QUOTE]
I would seriously consider replacing all of the rubber suspension components, namely the upper and lower control arms and the shock bushings. I would also look at the motor mounts to see if they are leaking. From there, wheel bearings and possibly the shocks themselves and tie-rod ends and ball joints. It would probably be a good idea to have the drive shaft joints looked and the sway bar mount bushings - also rubber. Basically any rubber in the suspension and drive line you can find.
Does GM not have service recommendations for 200,000 mile service, 300,000 mile service, etc. for this car? Not sure if I need tie rods, wheels are out of round, or if I need other front end components such as control arms. Wish there were some “replace at XYZ miles” guides which seem to be missing from the manual.
./QUOTE]
I would seriously consider replacing all of the rubber suspension components, namely the upper and lower control arms and the shock bushings. I would also look at the motor mounts to see if they are leaking. From there, wheel bearings and possibly the shocks themselves and tie-rod ends and ball joints. It would probably be a good idea to have the drive shaft joints looked and the sway bar mount bushings - also rubber. Basically any rubber in the suspension and drive line you can find.
Thank you. I want the car to be reliable for the next 170,000 miles and this is exactly what I was looking for. The dealer didn't have any issues aligning it the last time, but the alignment drifted REALLY quickly this last time (less than a year of driving) so something seems to be off.
Appreciate those who have 200k+ and knowledge of how to keep these cars running. I'm hoping to have this car for 350,000 miles and want to keep up on all the necessary maintenance to get it there.
Appreciate those who have 200k+ and knowledge of how to keep these cars running. I'm hoping to have this car for 350,000 miles and want to keep up on all the necessary maintenance to get it there.
There's a guy on C1-C2 (Steve Stone) who is the original owner of a '63 convertible. He drives the wheels off the thing, I think he's over 610,000 miles with it. Keep driving yours!
I have a 2009 C6/1LT/auto that has served me well for many years. I am the second owner and have driven the car daily since 2014 in which it had 68k miles. The car has around 170k miles now and has developed some strange electrical issues. The car has been to several shops and dealers who have thrown a boatload of parts at the vehicle, only to have the problems return. As of yesterday, the car has experienced:
Entire radio display is dark and will not even provide backlighting to the buttons when the headlights are on.
Navigation head unit is non-functional and even the CD stuck in the stereo refuses to be ejected.
One headlight (usually the driver side) goes out when the Left turn signal is activated.
Map lights and other lights stay on even after leaving the car, but lock/unlocking cures this (sometimes).
I recently took the car on a 800 mile road trip and found the interior lights staying on at rest areas, even after leaving the car and locking with the keyfob. This would stay on after the 20 minute "Retained Accessory Power" feature and remain on until I started the car. Within the past week, the car has experienced:
Alarm going off even after you've unlocked the car with the factory keyfob/remote.
Unable to pair a second keyfob/remote using the procedure in the owner's manual.
Random lights such as tail lights, reverse lamps, and other lights on when parked.
Interior bulbs burning out at random (driver side footrest, DIC buttons, HVAC defrost).
Dealers have been unsuccessful in repairing the car after throwing numerous parts at it. The car has received two alternator replacements (based on this I am assuming #3 is what's in the car), a new fuel pump and fuel pump sending unit (they were diagnosed as bad), multiple Optima Yellowtop batteries (three replacements), and it still drains the battery after sitting for several days. I have to keep the car on a battery tender daily even though it sees 250-450 miles of travel per week, as it's a daily driver.
The car does have an aftermarket stereo in it, installed with a PAC RP5-GM11 interface adapter, but that has been installed since 2014. Just to rule that out, I swapped in a different aftermarket stereo just to eliminate the existing Alpine head unit (in case it had an internal short). I can try putting the OE stereo back in, which would enable the factory XM and OnStar features, but am not sure if the radio is the culprit - if it is, why did it take 8 years to occur (and there are no shorts on the harness, connections were soldered and not crimped).
Today the car showed all of the same electrical issues with the driver side headlight turning off regularly when the turn signals were enabled. Multiple times I would hear relay noises that shouldn't be happening, even after I opened the hood. The fuel pump relay (#55) is very hot to the touch, and the battery isn't charging after a 20 minute drive - when put on a battery tender it showed the battery was depleted. Voltage when sitting is around 12.1-12.3V right after shutting off the engine.
I'm afraid to take this thing back into a shop again and receive thousands of dollars of parts thrown at it and no resolution. The only thing I can think of is try cleaning connectors/grounds, put the factory stereo back in, and then hope I find a decent repair facility that isn't going to play the "keep replacing things until it fixes the problem" game because that's all most shops have done so far.
If you had an excellent condition C6, with only this minor problem, what would you do?
long shot and probably not the issue but, I'll throw it out there, as you are the second owner, is their any chance that the original owner experienced and water / flood damage? with the many types of issues affecting several different systems,
just thinking of what else would have such a far reaching effect. but i also agree with what some others have mentioned. checking your grounds would be the minimum thing to check.
don't you just love computer based vehicles? the old suck, bang, blow doesn't carry as much weight as it used to.
good luck though!
Is it worth disabling OnStar now that the 2G cell modems in our cars are no longer supported?
I have cleaned several grounds, removed the aftermarket radio (ran the car with no radio except PAC RP5-GM11 harness to prevent the car from throwing faults), and think I’m down to one or two things for parasitic draw.
I could use a clamp on ammeter and check each circuit, but want to know if it’s even worth my time to do that for the OnStar module as it’s no longer capable of being used.
My thought is might as well disable it as a troubleshooting step.
Logically if the car had no issues for 8 years you have a corrosion problem. Start with a new battery because yours even if brand new is beat up from the constant discharge. Before reconnecting it. Start by going through the car’s electrical system in order. Start with the alternator clean the connection point and connector and add a dab of dielectric grease. Dano has a good thread on rebuilding the stock alternator I recommend looking it up. Ideally, a 6 phase mechman is worth coin and adding the big 3 helps dramatically.
Next, move to the fuse box Start by pushing the engine compartment upper fuse block from the lower block, clean the upper fuse block and lower blocks connectors, touch of dielectric grease, and reinstall the upper fuse block and make sure that the fuse bolt positive terminal nut is tight when you reconnect the battery cable to it. To add here, it helps to pull all the fuses and relays to give their U connectors shot of electrical contact cleaner as well.
Now on too the battery cables. Make sure you clean them with a wire brush and put dielectric grease on both cables. Underneath the battery tray there are two main grounds I recommend cleaning.
After that move down to the starter. The main issue is the starter solenoid. The plastic melts overtime and causes a weak connection. If all looks ok disconnect the the nuts and clean them and add a dab of dielectric grease. Also check the ground on the engine block is tight and not corroded. This is a super important ground to keep clean and connection tight.
Now let’s move inside to the passenger footwell. Unplug the onstar since it causes parasitic draw. Next, the blue connectors on the bcm. Unplug them and clean with cleaner and add a dab of dielectric grease. Plug them back in.
On to the ecm in the fender. You’ll need to remove the tire. Unplug all the wires and give them all a shot of cleaner and dab of dielectric grease. Plug back in. Clean the grounds there as well.
*You can also do this to all the connections behind the center console. RCDLR, Radio, HVAC. In fact everything through the entire car. Since Gm didn’t add any dielectric grease from
factory to any connection or ground.
Logically if the car had no issues for 8 years you have a corrosion problem. Start with a new battery because yours even if brand new is beat up from the constant discharge. Before reconnecting it. Start by going through the car’s electrical system in order. Start with the alternator clean the connection point and connector and add a dab of dielectric grease. Dano has a good thread on rebuilding the stock alternator I recommend looking it up. Ideally, a 6 phase mechman is worth coin and adding the big 3 helps dramatically.
Next, move to the fuse box Start by pushing the engine compartment upper fuse block from the lower block, clean the upper fuse block and lower blocks connectors, touch of dielectric grease, and reinstall the upper fuse block and make sure that the fuse bolt positive terminal nut is tight when you reconnect the battery cable to it. To add here, it helps to pull all the fuses and relays to give their U connectors shot of electrical contact cleaner as well.
Now on too the battery cables. Make sure you clean them with a wire brush and put dielectric grease on both cables. Underneath the battery tray there are two main grounds I recommend cleaning.
After that move down to the starter. The main issue is the starter solenoid. The plastic melts overtime and causes a weak connection. If all looks ok disconnect the the nuts and clean them and add a dab of dielectric grease. Also check the ground on the engine block is tight and not corroded. This is a super important ground to keep clean and connection tight.
Now let’s move inside to the passenger footwell. Unplug the onstar since it causes parasitic draw. Next, the blue connectors on the bcm. Unplug them and clean with cleaner and add a dab of dielectric grease. Plug them back in.
On to the ecm in the fender. You’ll need to remove the tire. Unplug all the wires and give them all a shot of cleaner and dab of dielectric grease. Plug back in. Clean the grounds there as well.
*You can also do this to all the connections behind the center console. RCDLR, Radio, HVAC. In fact everything through the entire car. Since Gm didn’t add any dielectric grease from
factory to any connection or ground.
Now you can put a new battery back in lol
***use crc red can for the cleaner.
GM didn’t use dielectric grease because it’s an insulator !!…you especially don’t want to use it on any low current circuits in the ECM and airbag module connections…they do make “conductive” grease and what I like to use is Stabilant 122…actually improves the conductivity of a connection.
GM didn’t use dielectric grease because it’s an insulator !!…you especially don’t want to use it on any low current circuits in the ECM and airbag module connections…they do make “conductive” grease and what I like to use is Stabilant 122…actually improves the conductivity of a connection.
Dielectric grease is for plugs tightness and mechanical functionning (good locking and easy to unlock further). You have to put grease on plastic rubbing surfaces all around the plug and on lever fulcrum. Never on cooper or where it can sip on it !
I have fixed an odd issue on break rear lamps which never lighted off by only cleaning BCM plugs like said above by Petera90.
Last edited by Blackship; Jan 12, 2023 at 10:17 AM.
) You can set up a small kit with whatever you want, but absolutely don't lave home without it.
