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Alarm? DME? No start stumper

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Just got a '98 tipper (my first 986). Natch, no records, but the story is that a coolant line had come off and the dealer recommended engine replacement. That's why the original owner decided to sell - long story, but can't get records from original owner. Car sat totally dead for about a year. My first priority is to validate that the engine is "bad" and check compression, leak down, etc. However, it won't crank. Everything lights up - it just won't crank the starter (yes, I have voltage at term 30 on the starter and a good ground), along with a new battery.


1. Verified all fuses are good and seated properly.

2. Checked ignition switch (proper function and continuity in all positions verified on switch and at load locations)

3. Checked P/N shifter start interlock - sends correct signal to the DME.

4. Jumped starter and it spins properly and engine turns well with no odd grinding or noise :) .

5. Checked all related relays (start lock, fuel pump, MFI-DI).


1. Have proper ground at pin 6 and 12V at pin 26 with ign 'off' which is correct.

2. Measured source voltage at engine sensors from pin 54 in DME which is correct (DME plugged to connector).


1. Both keys function correctly (except for start) and will remotely lock/unlock.

2. If alarm has been set, then unlock command sent, after about a minute, everything locks again automatically. Second unlock command works and does not repeat the automatic lock event.

3. Central lock switch functions and actuates locks, but LED indicator on switch (?) does not come on.

4. Checked and changed alarm unit fuse.

5. Measured 7.5V at pin 88 on the DME no matter if ign is on or off and can't verify if that is good or bad.


1. OBD II reader will show connection to car, but displays "erpr" which is not in the error code directory, nor found anywhere I've looked, but believe it means "error - no power".

2. Just for fun, tried the OBD II fault code erase function, but it returned an odd undecipherable error message.

3. Entering radio security code (as written in original owner's manual) does not unlock the radio.


Either the alarm has immobilized the car or the DME is faulty. I'm leaning toward immobilizing.

Based on the great info in here, I'm guessing I'm going to have to have the car flatbedded to the dealer to get a diagnosis of the computers, then get the alarm reset then re-flatbed back home assuming the engine is toast but eliminating the electrics as a problem. I did consider Durametric, but if the problem is the alarm, that won't get me where I need to be and I figure to put that cost into the flatbedding/diagnosis.

Any thoughts, recommendations, suggestions would be greatly appreciated!

Edited by JP Rodkey
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Have you tried locking the car manually with the key and then unlocking it the same way (to reset the alarm system)?

Is this a US/Canada car or RoW?

Where are you located?

Yes, tried several different combinations of lock/unlock (with key and with remote) to no avail. When alarm is set, LED flashes twice with long pause between next set of flashes. Disarm causes five or six rapid flashes of LED. WSM is a bit hard to decipher, at least for me. I'm located in the Milwaukee area.

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  • Admin

Things to look at:

1. Check the ground wire from the engine to chassis (near the spark plugs it is on the right side of the car on a Carrera but I don't remember which side on a Boxster).

2. If the car was outside there is a chance the alarm box (under the drivers seat) got wet. To check, disconnect the battery; remove the drivers seat and remove and open the box looking for water damage.

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I've been in the same predicament many times, unfortunately, I don't recall all the solutions (do a serch of my posts, here and elsware).

Several times it was the security (?) box under the drivers seat. If flooded, it can get really weird. Might take it out (easy) and have a look inside, if its moldy looking, or shows other signs corrosion...bingo . They can easily be flooded and corroded if your drains are plugged.

Another little stumper; disconnected engine ground straps. Figured this one out by running a jumper cable from the battery to the block near the starter.

Finally, to measure the health of your engine as you describe, you can jump the starter without to much fuss. It won't start but and you can't warm it up (or...). But it will spin and from that you can learn a few things.

Regards, PK

P.S. While Loren was posting, I was typing...I'm really not a parrot.

Edited by pk2
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Good stuff.

I did run a jumper directly from battery ground to engine, but that didn't change things.

There are no signs of water damage or accumulation of any kind - carpet, seat, wiring, ground connection in floor pan all look as new - but it's still possible and will check. As mentioned in the OP, the engine does spin. The first thing I did was rule out a faulty starter

I know enough about the alarm system to know the keys are programmed to the box and it's supposed to be programmed in the car. However, the box is THE brain, so I'm wondering if just the alarm box and the DME can go to the dealer without the car?

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Your one step ahead of me on every count,

I would defiantly look inside the box under the seat, Nothing to lose. It can look just ducky on the outside, no “ring around the toilet”. But, inside, a few signs of rust and corrosion, residue in the plastic box... adios....

Skip the dealer option, you might do well to find a kindly sole with a Durametric or PS2. Any decent indie will have the goods to. Me, a volt meter and wiring diagrams seems to get me through. With that said, EVERYTHING has a tentacle into that security box.....one splurch is all it takes.

Your quandary is is interesting. My car was all thrashed up, totaled and unloved when I bought it. Everything that could go wrong did. It's now happily buzzing (for now) around at 270hp. The funnest p-car I ever ownded

Regards, PK

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Thanks, pk2. This afternoon, I did remove the alarm computer. It looked absolutely new inside and out. However, it was obvious the driver seat had been removed in the past, and the alarm box was not locked into the tabs on the floorpan. No way to know the full story. I would go ahead and buy the Durametric, but unless I misunderstand, it's useless to reset alarm codes which means if the alarm computer is responsible for immobilization, there isn't anything I can do? I'm comfortable with a VM and fairly comfortable with the diagrams, but we can only go so far inside the DME and alarm. Keep up the suggestions!

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Ode to Joy! Amazing. After most of yesterday working through the electrics many times over, I decided to sleep on it and ponder investing in the Durametric or simply hauling off to the dealer (after a rush online order for some K-Y). Spent a half hour reading threads in here and rethinking the whole process. I have a couple of later 928s and therefore somewhat familiar with Porsche's DME approach. So...........what the heck.......disconnected the neg battery terminal for 30 seconds and refit. Turn of ignition worked!

Now the real work starts because the engine is supposed to be "bad" and I can now focus on that. Thanks to all who looked at the thread and especially those who posted. Hopefully, this might help someone else.

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