Electric gremlins in my 02 996TT - ignition switch?

[laalves]

Hi all,

 

I currently have a few electric gremlins in my car that have been sneaking in in the last few months:

 

1. The headlight washers stopped working. Fuses all ok. Took the water pump off the reservoir and it was swollen and cracked open so I replaced it, thinking I nailed it. It didn't. The pump is working fine in the bench but still no joy... Got a relay to exchange and test. Nope. So I'm guessing headlight switch (going to check next if the headlight signal arrives at the relay) but...

 

2. A while back, I started getting occasional PSM fault followed by ABS fault. Durametric said Hot Film MAF and DME loss of comms (the usual ones). Got a new Bosch MAF (figured a 14 year old MAF was due for replacement anyway), still the problem persisted but much less. Replaced air filter, cleaned the air box, disappeared the issue BUT now I get it if I leave the car idling for a while, I will occasionally get the codes. Shutdown and restart clears the dash lights. The lights will not show up while driving, just when idling, which appears to rule out air leaks...

 

3. Occasionally, after starting the car, the windows would open by themselves, interior lights stay on for a while and it won't let me lock it with the inside button. Now, this happening 90% of the times I start, immediately after the start. All the rest of the lock/unlock system is working per spec, i.e., windows go down slightly pulling the handle, locks/unlocks with the remote, seat memory, detects correctly open bonnet/glove/arm rest lid, lights flash per spec, unlocks/locks with the key everything perfect, except this weird thing upon turning the key.

 

Question 1: could all this be a sign of a failing ignition switch (4A0 905 849 B)? Is it worth it buying a more expensive branded one (Magnetti-Marelli, Valeo, 20-40€, etc) or a 5€ unbranded?

 

Question 2: would I be better off replacing with the newer spec 996 347 017 07 full lock housing (I checked and have the older original one installed)? I can get a new one for 130€ versus the switch only for 5-40€, which is not a concern but still would like to know if it is worthwhile.

[JFP in PA]

Hi all,

 

I currently have a few electric gremlins in my car that have been sneaking in in the last few months:

 

1. The headlight washers stopped working. Fuses all ok. Took the water pump off the reservoir and it was swollen and cracked open so I replaced it, thinking I nailed it. It didn't. The pump is working fine in the bench but still no joy... Got a relay to exchange and test. Nope. So I'm guessing headlight switch (going to check next if the headlight signal arrives at the relay) but...

 

2. A while back, I started getting occasional PSM fault followed by ABS fault. Durametric said Hot Film MAF and DME loss of comms (the usual ones). Got a new Bosch MAF (figured a 14 year old MAF was due for replacement anyway), still the problem persisted but much less. Replaced air filter, cleaned the air box, disappeared the issue BUT now I get it if I leave the car idling for a while, I will occasionally get the codes. Shutdown and restart clears the dash lights. The lights will not show up while driving, just when idling, which appears to rule out air leaks...

 

3. Occasionally, after starting the car, the windows would open by themselves, interior lights stay on for a while and it won't let me lock it with the inside button. Now, this happening 90% of the times I start, immediately after the start. All the rest of the lock/unlock system is working per spec, i.e., windows go down slightly pulling the handle, locks/unlocks with the remote, seat memory, detects correctly open bonnet/glove/arm rest lid, lights flash per spec, unlocks/locks with the key everything perfect, except this weird thing upon turning the key.

 

Question 1: could all this be a sign of a failing ignition switch (4A0 905 849 B)? Is it worth it buying a more expensive branded one (Magnetti-Marelli, Valeo, 20-40€, etc) or a 5€ unbranded?

 

Question 2: would I be better off replacing with the newer spec 996 347 017 07 full lock housing (I checked and have the older original one installed)? I can get a new one for 130€ versus the switch only for 5-40€, which is not a concern but still would like to know if it is worthwhile.

 

The electrical section of the ignition switch is well know to cause problems in these cars, to the point that most shops carry replacement's in stock.  The electrical section of the switch is common to VW and Audi, and should be available at a low cost.

[jpflip]

I got mine at a Audi dealer and it is part# 4A0905849B. I've paid I think $40.00 (26 euro) here in Montreal (normally more expensive than anywhere...) Also a DIY can be found here (it is a boxer but almost the same) http://industryfigure.com/berkeley/Porsche/ignitionswitch.htm and also here: http://www.gagme.com/greg/996/ignition

Edited January 13, 2016 by jpflip

[laalves]

Thx both, but I know about prices and P/N of the switch, the questions I asked were a bit more specific. Ideas anyone?

[JFP in PA]

Thx both, but I know about prices and P/N of the switch, the questions I asked were a bit more specific. Ideas anyone?

 

We normally just replace the electrical section of the switch; they are cheap and easy to do.

[fpb111]

Sometimes a low/failing battery can cause the problems that you have. Check your battery and charging system.

[laalves]

Funny you mention that, it just died this morning with no pre-warning. 2-years old Porsche Moll. Ordered a Bosch S5 013, 100Ah 830A for half the OEM 80Ah 800A that's in place. My car originally had the M197 option, so has a huge battery tray ready for larger batteries, hence my ordering the biggest Bosch that fits.

[laalves]

Huge battery installed, fits just fine. Hope it lasts for more than a couple of years... As to the gremlins, I'll see in the upcoming days whether they'll go away. The new ignition switch has not arrived yet but I'll put it in anyway AFTER I determine whether the gremlins were battery related.

[laalves]

And here's the new battery in place - 353mm width.

[fpb111]

That wouldn't be a monster amp in the frunk would it? One that could suck the battery inside out in a 1/2 hour? If so that could contribute to the short battery life.

[laalves]

Nope, just a JBL Class D digital signal processor. I do have two Alpine Class D amps connected to the outputs of the JBL, however I installed all these in 2008 when I bought the car and the Porsche/Moll battery that came installed only died in 2012 or 2013. I dont' know how old it was before that but 4/5 years is very good already.

 

The Class D system I have in place is very good and power efficient. I remember doing the load calculations in 2008 and reaching the conclusion that I had ample reserve to spare, considering the battery and alternator specs. 

[laalves]

Meanwhile, the central lock issues went away after replacing the battery BUT the two other gremlins are still in the car.

 

- ABS, PSM off under the following circumstances: when idling, warm car, in neutral or park, after a couple of minutes, the warnings light up in the OBC display, while there is audible variation in the sound of the engine (rpm dropping 200 or 300, then up again). If I keep it in gear (Tip) while stopped, it doesn't happen. Durametric says:

P0103 Porsche fault code 115 - Hot film MAF sensor

5525 Incorrect data transfer with DME master control unit

This was happening a while back and replaced the MAF sensor with a new Bosch one. The issue remains, maybe less frequently but same deal. Turning the engine off and on resets the warnings.

 

- Headlight cleaning system does not work. Took the headlights off, and the water sprays out of both LH and RH tubes, so electrically the system is workisng. I did replace the pump also, thinking it could have been a dead or weak pump, it was cracked open although it did run in the bench. Replaced it with a new one (made by Topran, not by VDO as the original in the car) but no joy. How come the sprinklers are not popping?

 

Any ideas on my gremlins?