bal

Thought I'd see if anyone has any ideas about this...

Car: 2002 C2 cab. Driver side latch and exterior microswitch were replaced last year as was the front hood latch.

Symptoms:
1. Double beep when I try to lock with the key fob, and locks to do not lock.
2. Central locking switch LED always on.
3. Unlock possible with key fob.

Using Durametric, I get the following codes:
47 - Control locking synchronization
60 - Central locking limit position Lock not reached
61 - Central locking limit position Unlock not reached

Here's what I've done so far:
1. Assumed it was the passenger side latch causing an issue and replaced it. No change, so put the old one back.
2. Removed driver's seat and removed and inspected alarm control module (exterior and interior). No water incursion found. Circuit board looks OK: no burns or visible defects.
3. Followed the Bentley and Porsche workshop manual troubleshooting for these error codes (Workshop Manual is far more useful). No issues found.
4. Reviewed the schematics and tested continuity to ground and continuity between driver side and alarm module and passenger side and alarm module. No issues found.

Put it all back together and initially it seemed fine. Then it started to repeat the double beep.

Based on the above, I *think*:
* Both latches are good.
* Central locking switch is good.
* Alarm module is good.
* Wiring is good.

I see conflicting information about whether the exterior and interior door handle microswitches will cause a double beep or a single beep. Can anyone advise? I'd rather troubleshoot these than sending off the alarm module, DME and keys for diagnosis, which seems to be the next step according to the Workshop Manual.

bal

Took the alarm module apart to check for water damage, shorts, general unhappiness, but it looks good to me. I cleaned the exterior plugs with electrical contract cleaner too. I also checked the fuse and cleaned its contacts too.

cwilt

I just tested mine and both interior and exterior door handles cause a single beep.

I will think on this a while. Sounds like it could be an intermittent problem since you got it to go away briefly. How long did it work properly until you started having problems again? Did you do anything to the car before this started happening?

bal

Thanks.

The only other thing that I did was to lock and unlock with a new key fob that had been programmed for me. I've since tried the original key fob and also get the double beep with that, so I think that it was just a coincidence the new key fob gave me a double beep. When my mechanic plugged his PST2 into the car, he was not able to get any communication with the alarm module to read the status of the inputs. I have Durametric and when I run the module test, I get clicking of the relays in the control unit as well as in the door latches and then the double beep. However, I'm not able to perform any of the actuations in the Durametric actuations page. It may just be that the system thinks that it is in an unknown state. I am able to clear the codes, but they either go away and then come back or do not go away.

cwilt

Do you have a schematic for your car? I have the TT version and I wouldn't think it's any different but I'd be open to look at one for you. Sometimes it's something further back in the system that you wouldn't suspect.

Sounds like it could be a bad connection somewhere.

bal

Yes I have the schematic in the Bentley manual. I ran continuity tests between the door latch pins on each side and the appropriate pins on the alarm control module header plugs. This was in addition to following the specific troubleshooting steps in both Bentley and the WSM for the error codes. The only thing I've not done is to verify the functioning of the inner and outer handle door microswitches and continuity between their pins and the alarm control module. That's my next step I think.

cwilt

That's a good thought to check too. Post back when you have info. If you want me to look at the schematic, PM me your email and I will look at it.

sammaw

I have the same issue, which has started in the last two weeks. it is intermitted as last sunday back to normal and Monday back to double beeps. But if I try to relock on the key normally the second time it will lock. The interior locking switch is constantly light up, and will double beep if I try to click it with the car running. I am about to change the ignition switch as that seems to be the go to all for electrical faults. Will check back here to see what you have found.

bal

Thanks. I'll scan it in tomorrow.

bal

To my knowledge, my ignition switch has not been changed. I'll be interested to know what you find...

cwilt

They do cause issues and can be purchased fairly cheaply through Pelican for around $10 using non-oem. I replace them every couple of years for PM.

ECU Doctors

I don't see how an Ignition Switch problem can cause Central Locking issues when locking up your car.

OP, did this problem start after you got that 2nd Key Fob programmed to your car? If yes, I'm wondering if someone played around with the PST2 and changed any settings in your Alarm / Immobilizer System Module.

bal

Thanks ECU Doctors - you are of course the people that I would be sending my alarm module, DME and keys to if I end up going that route...

No, the problem existed before I had the new key fob, so my expectation that it was just coincidental that after working OK for a few minutes with the first key fob that it started doing the double beep when I used the second (new) key fob for the first time. It now continues to do the double beep with either key fob.

ditto

Looks like you tested the two door latches. What about the frunk and engine lid latches? If my frunk is not latched properly I get the double beep everytime. Try pushing down at the latch area while working the clicker.

bal

cwilt - Here's the schematic.









I also followed the troubleshooting steps in the Workshop Manual Section 90 Test Point 45 (Fault code 46, 47), Test Point 55 (Fault code 60) and Test Point 56 (Fault code 61). I found that the WSM has more detailed troubleshooting steps than the Bentley manual, and is a superset of what Bentley suggests testing.