Warning Battery/Generator-Help

I was putting a battery tender on my ' 06 Cayman S , I unplugged the trunk light, but inadvertently shorted the connection. I went into to fuse box and on the upper right hand side noticed a red circuit breaker looking plug . I pushed it , and the trunk light came back on. Now when I turned my car on it has a warning battery /generator light on. The battery is at 12 volts and with the car running it shows close to 14 volts. Any help is appreciated, since the nearest dealer is 80 miles. Regards Donnie

it seems to be charging...i would look over every fuse...if no joy its to the dealer

Re: Warning battery/generator light -Help Have you driven the car since then? If you can that may clear your warning light. Why disconnect the trunk light? If you are leaving the hood open there are a several threads explaining how that can be avoided while using a tender.

I have driven the car 120 miles since then. Funny thing is , when I turn the car off after I initially get the message and turn it on again, the message disappears. Regards Donnie

Sounds like a simple fault that needs to be cleared.

Thanks for your help. I'm going to find someone to plug in and try to clear it. Regards Donnie

In the process of installed brackets in the trunk to secure a 17" donut spare, I had to remove the plastic trim that makes up the storage bin in front of the battery , the master brake cylinder reserve and trunk light housing. In doing so, I blew the trunk light circuit and this also caused the drivers door window to stay slightly down when I closed the door. After checking every fuse (all good), I did a search on this website and found that I too had popped the red circuit breaker looking plug . But when I pushed it, in my CSs case, the trunk light did not work, the driver's door window stayed slightly down and the multifunctional PSM warning light activated as well as the warning message on the on-board computer. These faults were cleared by - turning on the ignition and lowering the driver's window all the way down by pushing to the first detent (not the second which activates the auto down function), then pushing the switch up to the first detent until it was all the way up and finally pushing the switch to the second detent. This resets the window's control module. - The multifunctional PSM warning was cleared by drivng the car around the block - As for the trunk light, it started working normally after I drove the car. After, having '70s and '80s Porsches, the complexity of the electronics on the CS is indeed a thing of wonder.

Great tip!

Hi, Donnie. Did you resolve this issue? I have same problem after engine replace and dealer cannot find why there this message is. They checked generator, wires between generator and DME , battery ... There is Porsche descriptions of this error code but this have not helped: -------------- P0621 Battery Warning Light Possible fault causes * Open circuit in line between generator and DME * Short circuit to ground in line between generator and DME * Short circuit to B+ in line between generator and DME * Generator faulty ------------------------ Thanks Andrey

Having the same issue after engine replacement. Anyone solved it?

CS'06 engine and engines that produced later have different electrical pinout of connectors that connect engine to control blocks of car. I don't remember now exactly where are located two wires that you need swap in connector to fix this issue after engine replacement. Ask your dealer to compare engine connectors pinouts in wires diagrams 2006 and 2008, for example.

Andrey, I appreciate the help and it does make me feel better about my issue. Were you the one who looked up the wiring diagrams or was there a shop I can contact to see if they remember which wires it was? My local Porsche dealership isn't the best, so I need to really do my homework before I say "fix this". They'd love nothing more than to spend thousands of my dollars while never fixing the issue.

I've contacted my dealer who fixed this issue. He have tried to restore history He recommend the following (This way was used for fixing my issue, my old engine was '06, new engine was '07. New engine had new wires to connect to DME ) 1. Take two wiring diagram, for CS 06 and CS 07. You need schemes 19A. 2. Take a look at DME connectors on both schemes (there are two connectors, B and C) You should see the pinout differences. Compare pins #19 of C-connector #12 of B-connector. 3. In my case dealer moved wire from #19 (C connector) to #12 (B connector) and it solved issue. Please, check and compare carefully wiring diagrams before work - there may be differences or mistakes. You understand I cannot guarantee any success. Moreover, it can be dangerous for you and your car equipment. I just recommend to give this info to dealer.

Need to bring this thread back to life briefly. Had the same problem after engine swap, as post suggested I looked at wiring harness. My 06 manual had the alternator wire in B12, new engine (told is was 06 Tip) was in C19. Swap is quick and simple, takes longer to get to connectors than change position. Just remember the risk of frying your computer before attempting. I've got a strange result after the swap and looking for some input First time you start the car the alternator light comes on. If you turn off the ignition and start the car again the light stays off. You can turn the car off and on again, remove the key, ect..... repeatedly and the light stays off. If you lock and unlock the doors, or let it sit long enough that the dash turns off then the alternator light will come back on with the next ignition cycle. Any ideas?

hello, my english is not good and i just register on your forum because of a permanent irritating error message! i have the same problem on my 997 carrera S (2005) with engine from 2008. The error message P0621 also indicate a part number: 997.618.622.00 Unfortunately, I can't find information on the internet by entering this part number. so my question is, does somebody have pictures from the connectors that have to be switched? Thanks in advance regards,

up!!! still looking for some help

I just had this problem and followed the steps and it is fixed. Here is some pics. First is where the Blue wire was in C 19 Second is where is needs to be B12 Third and Fourth are just how I did it. The pics loaded wrong but you can see what I mean.

i purchased a 2006 911S that had its original engine replaced with a 2008 Targa 911S engine. I have the message on the tachometer display "check battery or generator" when I turn the ignition key to ON. I can make it go away when I push the OBC lever. It comes back when driving sometimes and I push the lever to make it go away. I have checked the battery with a load tester and it is good, and monitored the system voltage when driving which is always 13.8 to 13.9 Volts DC. I think the system is operating fine and I have the same problem described here with the connector wiring change. I would like to know how difficult it is to get to these B and C connectors to make the wiring change and how hard it is to take out thee pin from one and move it to the other. It seems that it must be easy to damage the pin when doing this since I have done electronic technician work before. I would like to avoid having the Porsche dealer do this and have and independent shop that works on Porsches do this if possible. Anybody have an opinion about this. It seems hard to get to the connectors, but maybe it is not if a wheel is removed? Is there an adapter Porsche makes for this? Thanks in advance.

I made a previous posting about having this problem and thought I would help others by what I have learned. I have a 2006 911S with a 2008 911S engine. I read that "rxsevn89" had solved his problem by moving a wire from the DME ( ECU ) connector B-12 to C-19 and wondered if I had to do the same to fix my problem. I first tried removing the alternator and replacing the voltage regulator . My iCarsoft code reader for Porsches read a P0621 error code indicating a L terminal/circuit problem. After researching this with Porsche repair documentation, I found that it was either the alternator was bad or the lamp circuit wire was shorted to 12 volts, grounded, or broken/disconnected. These were the only possible causes for this problem. So after studying the Porsche electrical schematics for the engine wiring harness and the DME to engine wiring harness, I found that the engine wiring harness pins on both the TSX59_1 and TSX59_2 (the two 25 pin connectors on the end of the engine wiring harness) were no different between the 2005/6 model and the 2007/8 model. I did also discover that the alternator (generator) Lamp circuit signal wire did go to a different connector/pin at the DME on the different model years as rxsevn89 described. THis was true, but would not be a problem if the DME to engine wiring harness was not changed to the 2007/2008 version. So if only the engine and its wiring harness, and the DME wiring harness were all changed to the 2007/2008 versions, then the blue Lamp circuit wire will be ariving at the DME connector on C-19 instead of B-12. This would mean the wire from C-19 would need to be moved to B-12 for the DME to get the signal. If the 2006/7 DME to engine wiring harness was not changed to the 2007/2008 version, then that fix is not needed and there should not be any fix needed. I don't believe the DME needs to be changed to the 2007/2008 version, so don't know why anyone would change this DME harness. I determined this after studying the Porsche OEM schematics I obtained. I have an electronics technology background so I believe what I said to be correct. After I checked the connection from the alternator end of the blue wire with the engine harness end at TSX59_2 (there is a blue wire also on the other connector TSX59_1, but which connector is which is not clear in the Porsche information, I found a good connection. The connector on the right is _2 and the left is _1, as I discovered by comparing the colors of the wires to the schematics. I had removed both connectors plugs and replaced them, tightening the bayonet snuggly to insure good contacts. I then started my car, and I found that the DME check battery /generator message did not show anymore, and was not listed in the OBC / DME info page. I cleared the P0621 error code with my diagnostic tool. I restarted the car and still did not have this warning message display again. I think that the TSX59_2 engine wiring harness connector must have not been making a good contact and that was the source of my problem, not the alternator , and not the wiring. When I turn off the car and remove the key, then restart it, I see the message, and then see it in the info page, but if I turn off the car, restart it without removing the key, I don't see the message and it does not show in the info warnings. I am not sure why it shows at all, since the condition seems to be fixed, but at this time guess that it will take some time for the DME to not have it displayed at all, even after removing the key and restarting the engine. I know that when the engine trunk is left open, the DME displays the message for that, and when it is closed it does not, so expect that the check battery /generator message would go away for good, but maybe not the case. This was mentioned by Kermit so seems consistent with my experience. I hope that this information helps others that have this problem. I have spent a lot of time with this problem and have taken out the alternator twice, the first time to test the alternator and replace the voltage regulator , which was not bad, but at least it was not a factor anymore. Don't trust local auto stores' alternator testers with Porsche alternators because they test it as if it is their part model number, not Porsche 's, and I was told mine failed, when it was perfectly good. I had tested the diodes myself, and installed a new VR, and before I did this, it always put out about 13.9 volts at all RPMs, so it was not the problem. Please post any feedback or questions and I will try to answer them. I do recommend ALLDATAdiy.com Leading Source of Factory Automotive Repair Information for getting Porsche OEM repair information. From what I saw, the 2005 and 2006 were electrically the same and the 2007 and 2008 were also. Porsche used the 2005 schematics for the 2006 and the 2007 schematics for the 2008.

Hello, I speak English very well. I did the manipulation with the TXS59_1 connector and terminal 12 that I cleaned. I no longer have the alternator / battery fault msg when starting or while driving. I changed the battery , alternator / starter cable, alternator and I still had the fault message in an untimely way. When I bought the car I had no fault, the fault appeared after 2 to 3 years. The car is stored in the basement. Can be a little wet. My porsche 997 year 2005. It is possible that stored the car for a long time in a slightly damp environment, the contacts oxidize and the contact is no longer of good quality. Thank you for the info, I have the wiring diagram of the 997 and I was able to follow the very interesting process and I think I have solved my problem. Hello from France Regards