alarm problems

[valleyfred]

we got a 2001 boxster in our shop that came from another shop with non start situation after checking with pst2 found 14 codes we deleted all codes and got back to trying to start it again it would crank but no start check codes again and found code 39 and many others we went to see how many codes were in the immobilizer and found no communication so got new unit from dealer and program it

and car started ok for two days but after 20 starts or so code 1571 is in dme side no codes in the alarm side has anybody run into this problem is there anything we are doing wrong

[Loren]

:welcome:

P1571 (Porsche code 39) Immobilizer – Open Circuit / No Signal

– Open circuit in wiring between DME control module and alarm system

– Short circuit to ground or short circuit to B+

– Alarm system control module faulty

Check to see if it is wet under the left hand seat.

When water gets into the car the first place it runs to is the alarm/central locking/immobilizer box under that seat.

[valleyfred]

loren we have isolated the problem to terminal 86s when this terminal has 12.5 volts car will start sometimes it gets 5volts that is when it fail to crank and start we will track it until we find problem by the way no water under seat thanks for your reply

[Loren]

1. Check the power supply for the signal converter:Disconnect the connector on the signal converter. Voltmeter at plug housing pin 4 (negative) and pin 5 (positive).Ignition key inserted. Display: Battery voltage.2. Check the control line for the signal converter (pin 6) to the alarm control unit plug I pin 4 for continuity, positive short and ground short.3. Check the status line for the signal converter (pin 7) to the alarm control unit plug I pin 12 for continuity, positive short and ground short.4. Check the data line for the signal converter (pin 8) to the alarm control unit plug I pin 3 for continuity, positive short and ground short.