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LHD, Tiptronic, 1998 Carrera Coupe Hi all, new to the forum but I was consulting some existing threads in the public forums regarding similar and related issues before I started an attempt at this job. I have access to the full wiring diagrams for the vehicle, the pdf is "996 Wiring 1999-2000.pdf" and can be found on google. I had them printed out on large sheet paper so I could trace the wires and go through all the possible issues without having access to factory scanning tools. I'm an electronics and industrial instrumentation technician hoping to build more work experience and reputation in order to get access to more of these repair gigs in the future on higher model cars. I am working on a 1998 Carerra (Japan market) that was installed with a 'fancy' alarm system that sat on top of the existing setup and most of it was removed prior or at delivery, and I spent yesterday inspecting and repairing the wiring harness from the hack job that was previously in there. Today I went through the troubleshooting steps in order to eliminate probable causes of a no-crank. The current owner had ordered a new ACM (alarm control module) and had it re-programmed and had told me the porsche dealer said to him the reason it won't start is a 'wiring problem' which I believe I had repaired all the wiring so far in the vehicle. I still have the old ACM with the car, it's just un plugged in the front storage. After doing my troubleshooting today, I believe it to be the DME but my lack of understanding how the modules interact I'm not sure if it defective or just needing to have some re-programming of some sort which may require a porsche scan tool. Here's a take-away from my notes today; Check for B+ signal from ignition start to pin 30 on START LOCK RELAY SUPPORT REAR when ignition key set to START. B+ present Jumper pins 30 and 87 to test the relay is working. Turn ignition to START and check for engine cranking. Engine cranks. Check for B+ from pin 86 to the relay coil. B+ present Ground pin 85, and turn ignition to START. Engine cranks. Relay is working. Check for current path from pin 85 on the START LOCK RELAY SUPPORT REAR to the DME connector pin 66 ACTUATION START LOCK. YEL/VI/BR wire. There is a path. PIN 66 on the DME is not switching to ground, and this won't let the car crank and start. Check for path of ground from DME pin 68 START LOCK to the shifter PARK and NEUTRAL. It grounds in each position, open in any other. Check for B+ on pin 88 on the DME which is the DIAGNOSIS W LEAD, and the only wire from the alarm leading into the DME. From my understanding of the alarm system from reading the description of operation from my ALLDATA catalogue, there must be some sort of handshaking going on between the RFID in the key fob, the correct serial and cypher in the ACM and the DME in order for this pin 66 to ground to let the car start. Checks at 7.37V with the DME dis-connected, and 8.34V with the DME plug end connected. I also ohmed out this wire 0.2ohm to check for any unusual resistance because seeing that voltage struck me as unusual. Again, I'm not sure of how this system interacts but I can only assume it's correct as I also tried to measure this voltage with the spare ACM installed with the same reading. What I wanted to ask for; Is this a wiring problem, problem in the ACM or DME and what would have to be done to rectify it. Warm regards, Aurelius Attached are three helpful photos of the DME ACM and a sheet that I believe came with the new ACM