New clutch, New immobilizer, still no start, ideas?

[99boxster986]

So here's the story guys, I need any and all ideas as to what could be causing my 99 boxster 986 to still not want to turn over. Things I've replaced include the ignition switch in 2020 or 2021, and it worked fine after that. All the way up until the clutch burnt out and left it sitting for close to a year and a half. Now mind you I had been starting the car every so often to get the oil moving and coolant flowing with no problem. All the way until the beginning of may. I sent the car to get the clutch installed because I finally had enough cash to have the operation done by a reliable mechanic who has experience with porsche clutch jobs. Even he started it once before doing the job. Although he told me he had to try three times, which I figured was weird. Granted, it had been wet this year where I live and the back window is non existent. But I tried to cover it as best I could when I could. But it was inevitable that water got into my cabin and under my seat and corroded out my immobilizer unit. So clutch gets put in, mechanic tries to trouble shoot it but tells me he does deal with electrical issues, which is understandable. So I have the car towed home. I take out the seat and check immobilizer and it's toast. Which made sense as to what was happening and even the fact that I have no power window control. Everything pointed to that damn immobilizer. So I shelled out the $1224 to Specialized ECU Repair who have videos all over YouTube touting plug and play results. Sent them my key fob, my DCM/ECU, and the toasted immobilizer. I just got the new unit in today. So very excitedly, I went through the steps of reinstalling my DCM/ECU, my new and already programmed immobilizer unit, and the driver seat before plugging in the battery and trying to start the car. No luck. The mechanic told me he was messing with the relays in the back, he told me which ones he switched and so I switched them and instead of getting not even a click like before, I got a bunch of rapid clicks coming from the back trunk. Mind you, the clutch pedal is fully depressed and yes that dang carpet is out of the way to make sure. I'm so upset right now because I've spent close to 3k to make this car work and drive again and it has all the components but it just won't start. Also I still don't have power window control. And also my radio won't turn on, which it did before with my toasted immobilizer installed. Could it be something simple? (I also did drain all the water underneath the driver seat and squeezed that carpet out many times over the course of a month.) I currently have the battery on a charger and am hoping it's a case of the battery not being charged. But I'm not so sure. Because when it's a dead battery the dash and the climate control screen will dim and it won't turn over. This time everything stays lit with no dimming but I'm not getting any attempt for the car to turn over. Thanks in advance guys. Will update my troubleshooting on here for anyone experiencing the same issue. And yes, I have played with the steering wheel, it's not locked. I've tried putting the key in, leaving it on for a few minutes, taking it out, and then trying to crank it. But please, it feels like I'm missing something very obvious. 💀

[blue62]

First make sure your battery is good.
Take it in and have it load tested if there is any doubt.
Then make sure all your fuses are ok.
Then make sure all your relays are ok.
Test them to be sure just because a fuse looks good doesn't mean it is.
You can test all of the above with a Digital Volt Meter

[99boxster986]

Update: I've found a very helpful video on YouTube about diagnosing the no start and whittling down the possible causes. I've eliminated the clutch safety switch (bypassed it with a jumper wire) and tried the jumping the starter relay through pins 87 and 30. Now the car will crank no problem while the pins are jumped. I tested the relay but connecting the battery to it with some lead wires and I heard a click, but subsequent testing with a volt meter showed no continuity. So I have ordered a new starter relay and that should hopefully be my problem. But the question remains, why won't it run? I did see my gas was pretty much on empty. So I will add some more gas in the tank. Hopefully with this, the car will start. Will update as I find things out. Ideas and feedback greatly appreciated.

[78F350]

I suspect corrosion on the wire harness to the immobilizer box. Even with the car shut off with no key, power runs through at least one of the wires. Leave it wet for a while and it may completely corrode the connection.

[blue62]

Originally Posted by 99boxster986

Update: I've found a very helpful video on YouTube about diagnosing the no start and whittling down the possible causes. I've eliminated the clutch safety switch (bypassed it with a jumper wire) and tried the jumping the starter relay through pins 87 and 30. Now the car will crank no problem while the pins are jumped. I tested the relay but connecting the battery to it with some lead wires and I heard a click, but subsequent testing with a volt meter showed no continuity. So I have ordered a new starter relay and that should hopefully be my problem. But the question remains, why won't it run? I did see my gas was pretty much on empty. So I will add some more gas in the tank. Hopefully with this, the car will start. Will update as I find things out. Ideas and feedback greatly appreciated.

Again make sure ALL relays and fuses are good first.
If you don't know how to properly test a fuse or relay go to youtube.
Once you know for certain that all relays and fuses are good and you can get it to turn over with the key. If it will still not fire up then it is either not getting fuel or not getting spark.

[99boxster986]

Corrosion on the wiring harness to the immobilizer is a possibility, are there any cleaners or methods that you recommend for getting that cleaned out? And I hear you about checking all the fuses and relays. As for the starter relay that just came in today. Weirdest thing. I installed it, and it doesn't even want to turn over. But when I jump the pins for the relay, turns over but doesn't start. Shouldn't it turn over with my new relay since it works when it's jumped? I'm so confused on that part....

[Bush Pilot]

It’s clear at this point that the signal that drives the relay isnt getting there. There’s a signal that “throws the switch” (relay) and it’s not getting there.

[99boxster986]

Update: I've solved the problem! Actually 78F350 called it. Corrosion on the wiring harness to the immobilizer has been causing my no start. I used some electrical contact cleaner and it started up, I drove it to get some gas and after filling up, gave me some trouble turning back over but I suspect I just need to clean it a bit more. Took it for a good 20 mile drive to see how the new clutch feels and it feels great. Got some weird smells though, like clutch smells, so I'm going to need to double check with my mechanic to see if that's normal. I knew it was something simple. I just over looked the harness for whatever reason. I'm ecstatic I have this boxster back on the road and can now move on to the other pieces it needs like to replace the convertible top, new brakes, and cosmetic enhancements. Thanks for the help guys!

[tmanalio@yahoo.com]

Where is this immobilizer anyway ? I’m having the same issue. Battery voltage at 12.8 static.
Wold you mind telling me it’s location. 99 Boxster

[JFP in PA]

Under the driver's seat.

[tmanalio@yahoo.com]

Thanks, I had a similar problem with a Z4.