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Ok, so I just developed this issue where the car will not crank or turn over. I have read every single similar post I could find on the Internet so I wouldn't waste anyone's time:)

I previously replaced the ignition switch about 2 months ago just because the spring was a little weak.

I have bypassed the clutch switch. The battery is new. I have checked the relay, and even swapped it out with one nearby with the same value. I can start the car no problem by removing relay and jumping the wires across terminals to the output signal.

So, I know starter is good, clutch switch isn't the issue, not battery, not relay, and since I can start it jumping the relay terminals, I'm left thinking that the ignition switch is bad already?

Are there likely options I am missing?

Any thoughts, or suggestions would be greatly appreciated.

Thank you.

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Since you can start the car by jumping the start lock relay (I assume you jumped pin 3 and pin 5 then turn the key to crank), the ignition switch should be good. Then it should be one of the following?

- bad relay

- DME to relay open circuit

- DME detects that the clutch switch is not closed so it doesn't activate the relay

Next I think you should check pins 2 and 7 of the relay to see if you get power.

Edited by Ahsai

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Is the immobilizer be released? Try with the spare key, an error in the immobilizer system can sometimes occur, such errors are easy to figure out with a Porsche specific diagnostic device.

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Since you can start the car by jumping the start lock relay (I assume you jumped pin 3 and pin 5 then turn the key to crank), the ignition switch should be good. Then it should be one of the following?

- bad relay

- DME to relay open circuit

- DME detects that the clutch switch is not closed so it doesn't activate the relay

Next I think you should check pins 2 and 7 of the relay to see if you get power.

I don't recall which pins I jumped to start, but I didn't need to turn the key to crank, as long as ignition is on. So I don't think it eliminates the switch since it is essentially bypassed by the momentary jump by bridging.

The relay has been switched with another one currently in use on the car, and same thing.

The clutch switch is bypassed with jumper, I can start car from outside of vehicle by jumping the relay momentarily.

I will check pins 2 and 7 this a.m.

Do you have any idea where the relay gets the second signal from. I haven't seen a P&ID to see where each terminal gets signal.

Thank you very much for your input, we'll see what those pins put out.

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Is the immobilizer be released? Try with the spare key, an error in the immobilizer system can sometimes occur, such errors are easy to figure out with a Porsche specific diagnostic device.

I thought about that, my remote has never worked since I've owned it. I don't have a spare key unfortunately, both of these are on my short list to do.

I'm assuming that since I can easily bypass the relay and start the car in 10 seconds, that the immobilizer is not on, otherwise it would kind of be a joke.

I am going to buy a Durametric ASAP, I know it would/will help immensely.

I really thought it might be the immobilizer because it was narrowing down to not many other options. However, if I can jump the car from the relay terminal, and drive the car without any issue, I'm wondering if the immobilizer just immobilizes the ignition switch, and not the starter which would be a total joke.

I appreciate the feedback, these responses are what I need to figure this out. Thank you.

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I think that bridging the start lock relay will effectively bypass the immobiliser. I agree with RFM that a diagnostic check is the place to start.

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Is the immobilizer be released? Try with the spare key, an error in the immobilizer system can sometimes occur, such errors are easy to figure out with a Porsche specific diagnostic device.

I thought about that, my remote has never worked since I've owned it. I don't have a spare key unfortunately, both of these are on my short list to do.

I'm assuming that since I can easily bypass the relay and start the car in 10 seconds, that the immobilizer is not on, otherwise it would kind of be a joke.

I am going to buy a Durametric ASAP, I know it would/will help immensely.

I really thought it might be the immobilizer because it was narrowing down to not many other options. However, if I can jump the car from the relay terminal, and drive the car without any issue, I'm wondering if the immobilizer just immobilizes the ignition switch, and not the starter which would be a total joke.

I appreciate the feedback, these responses are what I need to figure this out. Thank you.

According to Bentley manual, the immobilizer disables the starter, fuel injection, and ignition if the key transponder is not recognized. Since your car starts when you bridged the start lock relay, I think your immobilizer is fine. Otherwise it will be a joke like you said.

I have the wiring diagram in front of me now. When you turn the key to crank the engine, the ignition switch supplies battery +ve power to pin 3 (term 30 of the relay), then the relay (should already be activated at this point) sends the power to pin 5 (term 87 of relay) which is connected directly to the starter solenoid.

Now the coil of the relay: +ve power appears at pin 7 (term 86 of relay) then the DME grounds pin 2 (term 85 of relay) ***IF*** everything checks out i.e., clutch switch closed and immobilizer cleared

So I think you must have bridged pin 7 to pin 5 before. If you turn the key to crank, you should see power at pin 3. If not, your ignition switch is not working or there's an open circuit between the switch and the relay.

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Is the immobilizer be released? Try with the spare key, an error in the immobilizer system can sometimes occur, such errors are easy to figure out with a Porsche specific diagnostic device.

I thought about that, my remote has never worked since I've owned it. I don't have a spare key unfortunately, both of these are on my short list to do.

I'm assuming that since I can easily bypass the relay and start the car in 10 seconds, that the immobilizer is not on, otherwise it would kind of be a joke.

I am going to buy a Durametric ASAP, I know it would/will help immensely.

I really thought it might be the immobilizer because it was narrowing down to not many other options. However, if I can jump the car from the relay terminal, and drive the car without any issue, I'm wondering if the immobilizer just immobilizes the ignition switch, and not the starter which would be a total joke.

I appreciate the feedback, these responses are what I need to figure this out. Thank you.

According to Bentley manual, the immobilizer disables the starter, fuel injection, and ignition if the key transponder is not recognized. Since your car starts when you bridged the start lock relay, I think your immobilizer is fine. Otherwise it will be a joke like you said.

I have the wiring diagram in front of me now. When you turn the key to crank the engine, the ignition switch supplies battery +ve power to pin 3 (term 30 of the relay), then the relay (should already be activated at this point) sends the power to pin 5 (term 87 of relay) which is connected directly to the starter solenoid.

Now the coil of the relay: +ve power appears at pin 7 (term 86 of relay) then the DME grounds pin 2 (term 85 of relay) ***IF*** everything checks out i.e., clutch switch closed and immobilizer cleared

So I think you must have bridged pin 7 to pin 5 before. If you turn the key to crank, you should see power at pin 3. If not, your ignition switch is not working or there's an open circuit between the switch and the relay.

Thank you for the pin out designations, very helpful and appreciated. I guess all I need to do at this point is to check pin 3.

This is the deduction I came to above as well, is that it has to be the ignition switch. With the conditions I have described above, is there any possibility that could be taking place? Each component either tested as functioning, or bypassed to eliminate it.

I am always a skeptic to believe that a part that is only a few months old would suddenly fail so quickly, although I do know it happens.

It's not like it was difficult to replace, and by far one of the cheapest Porsche repairs imaginable, so I guess I should be grateful, right?

Thanks again for taking the time to look that up for me. I will report back with results unless you think of another possibility missed.

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I think that bridging the start lock relay will effectively bypass the immobiliser. I agree with RFM that a diagnostic check is the place to start.

I hope for every Porsche owners sake that this is not the case. I am getting a Durametric soon, was kind of torn between hoping to find a used pro version on ebay vs buying a new enthusiast from durametric. Thanks for your input.

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You're welcome, Bluesteel. I can't think of other scenarios yet. If you do get power at pin 3 when you turn the key to crank, you can just bridge pin 3 and pin 5 to bypass the relay. Based on what you have tested I don't expect this to happen though.

I agree that it makes sense for the immobilizer to disable fuel injection and ignition all together, the last line of defense. Anyone can hotwire the starter on almost any car...

Edited by Ahsai

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I think that bridging the start lock relay will effectively bypass the immobiliser. I agree with RFM that a diagnostic check is the place to start.

I hope for every Porsche owners sake that this is not the case. I am getting a Durametric soon, was kind of torn between hoping to find a used pro version on ebay vs buying a new enthusiast from durametric. Thanks for your input.

Sorry, I didn't make myself clear. I think that bypassing the Start-lock relay will stop the DME immobiliser release terminal from inhibiting the starter motor. (I think that is what RFM was suggesting). Therefore, I think it sounds like a bad relay, or the DME is not giving the startlock relay a signal. A diagnostic check should show any faults in the DME

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I think that bridging the start lock relay will effectively bypass the immobiliser. I agree with RFM that a diagnostic check is the place to start.

I hope for every Porsche owners sake that this is not the case. I am getting a Durametric soon, was kind of torn between hoping to find a used pro version on ebay vs buying a new enthusiast from durametric. Thanks for your input.

Sorry, I didn't make myself clear. I think that bypassing the Start-lock relay will stop the DME immobiliser release terminal from inhibiting the starter motor. (I think that is what RFM was suggesting). Therefore, I think it sounds like a bad relay, or the DME is not giving the startlock relay a signal. A diagnostic check should show any faults in the DME

Oh right, he still needs to check pins 2&7 for power to the relay coil like I suggesed in post #2. For some reason I thought he has already done that. I think we are zooming in...

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Ok, after trying to think too hard about this, thinking I was missing something, I went with my thought from my first post. I went out and bought another ignition switch. The last one was only a couple months old and probably only had a couple dozen starts on it. I bought the first from Napa, and the new one from Autozone. I put the new one in and it worked right away, tried it a dozen times. The one at Autozone costs 3 times as much but is hopefully worth it. Thanks for reading my post, and any input, now to sort through the cab top...

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Ok, after trying to think too hard about this, thinking I was missing something, I went with my thought from my first post. I went out and bought another ignition switch. The last one was only a couple months old and probably only had a couple dozen starts on it. I bought the first from Napa, and the new one from Autozone. I put the new one in and it worked right away, tried it a dozen times. The one at Autozone costs 3 times as much but is hopefully worth it. Thanks for reading my post, and any input, now to sort through the cab top...

Well done!

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