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 3.4 - can't get the engine to crank at all. No clicks, nothing. Battery is good, dash lights light up normal, but I can't engage the accessories (power windows, locks, sunroof) nor will the starter fire up. I've checked all the usual - ignition switch appears smooth, bypassed clutch pedal micro switch - to no avail. Am I missing anything here? Any insight is appreciated.

Edited by GLIDE

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You may have multiple issues but at least you can try to jump the start lock relay to crank the car and do some troubleshooting using this thread

http://www.renntech.org/forums/topic/45047-2000-996-wont-turn-over/

If you get the starter to spin but engine still can't fire up, you will have to check if there's fuel injection and ignition. If not, it may be the immobilizer disabling those or there are other reasons such as bad/no crank position signal.

Edited by Ahsai

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Thanks Ahsai.

I'll be honest - I am not terribly strong at electrical troubleshooting. I'm wondering where you all are identifying the Pin #s? I've got the FSM and can't connect the dots! I'm looking at Sheet 12 of wiring diagrams. For example, how do I check pin 54 as suggested below (take from old thread where guy had similar problem- unfortunately no conclusion)?

Can I jump fuel pump and ignition relays to get the car to start?

Thanks in advance.

On March 8, 2010 at 3:01 PM, Paul 996 said:

Here's what the garage has said:

Diagnostics does not pick up DME (ECU not responding)

Check voltage at starter - 12V

Crank key - No voltage at trigger on starter

Checked wiring diagram - System has a starter lock and MFI relays

Change relays - No difference

Connected terminal 30 & 87 on starter lock relay - This allowed engine to crank, but not fire. This side of circuit ok.

Thoughts currently - Either relay trigger circuit faulty or ECU

Power to relays, but not trigger signals. Wiring seems ok.

Check continuity of wires - All ok

Check pin for trigger switch (Pin 54 of ECU = UB switched) - This controls Air mass, MFI and DI relay, Injection relay, Oxygen sensor, Secondary airpump relay, Fuel pump (through a connecting relay)

This item is not switching - Controlled directly by ECU

Check pin 26 (Referred to as terminal 30 on wiring diagram - feeds MFI and DI relay also) - Has the required 5V switching voltage

In conclusion the ECU control from Pin 54 is causing the problem. This is the direct control for the majority of engine fuelling systems. Therefore an internal ECU fault.

Still waiting to find out the results...

Edited by GLIDE

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Thanks Ahsai.

I jumped pin 3 to 5 on the start lock relay. Cranked very well but would not start. One thing I expected was to get a live oil pressure reading - the gauge simply went to max and stayed there throughout cranking session. Is this to be expected?

Doesn't appear the fuel pump or ignition are active. I'll be honest - I am not terribly strong at electrical troubleshooting. I'm wondering where you all are identifying the Pin #s? I've got the FSM and can't connect the dots! I'm looking at Sheet 12 of wiring diagrams. For example, how do I check pin 54 as suggested below (take from old thread where guy had similar problem- unfortunately no conclusion)?

Can I jump fuel pump and ignition relays to get the car to start? Anyone in Denver area with a Porsche diagnostics tool interested in coming by?

Peripheral q: the frunk and decklid release levers feel "locked". It's a 99- cable actuated. Is there some sort of locking mechanism for those?

Thanks in advance.

Here's what the garage has said:

Diagnostics does not pick up DME (ECU not responding)

Check voltage at starter - 12V

Crank key - No voltage at trigger on starter

Checked wiring diagram - System has a starter lock and MFI relays

Change relays - No difference

Connected terminal 30 & 87 on starter lock relay - This allowed engine to crank, but not fire. This side of circuit ok.

Thoughts currently - Either relay trigger circuit faulty or ECU

Power to relays, but not trigger signals. Wiring seems ok.

Check continuity of wires - All ok

Check pin for trigger switch (Pin 54 of ECU = UB switched) - This controls Air mass, MFI and DI relay, Injection relay, Oxygen sensor, Secondary airpump relay, Fuel pump (through a connecting relay)

This item is not switching - Controlled directly by ECU

Check pin 26 (Referred to as terminal 30 on wiring diagram - feeds MFI and DI relay also) - Has the required 5V switching voltage

In conclusion the ECU control from Pin 54 is causing the problem. This is the direct control for the majority of engine fuelling systems. Therefore an internal ECU fault.

Still waiting to find out the results...

Ok, at least your starter and ignition switch are working. No, oil pressure gauge should read very close to 0-1 when cranking. Most likely the oil pressure sensor is not connected or the sensor is bad (disconnect = infinite resistance = highest reading).

I'm reading the exact same wiring diagrams as you for the pins, focusing on sheets 12 and 16. You cannot just jump the fuel pump and ignition and expect the engine to fire up. There are many possibilities and unfortunately you will have to eliminate them one by one, starting with the easiest.

- Check fuse B8 and ALL the other fuses that are related to engine, DME, etc. http://forums.rennlist.com/rennforums/8516331-post7.html

- Check the fuse on the immobilizer unit.

To check the pins on the DME directly with the DME still connected, you need the DME breakout box. I would suggest checking other points to verify if the DME is even trying to fire the engine (e.g., sheet 12, M113 you see a small square merging point called "26"., which is directly connected to pin #54 of the DME. If the DME activates the fuel/ignition, this point will have 12v and so will all the lines that are connected to it. Therefore, you can check pin #7 of secondary air injection relay, which is a lot easier to access. Of course, this assumes you don't have a wiring problem so if you do see 12v with key on engine off, that means the DME is at least trying to activate the fuel/ignition.

Edited by Ahsai

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On May 29, 2014 at 10:26 AM, 987_RDC said:

Buy a paired ECU/Immobilizer/etc from eBay and swap it all in.

Thought about that. 

Edited by GLIDE

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Thanks Ahsai.

I jumped pin 3 to 5 on the start lock relay. Cranked very well but would not start. One thing I expected was to get a live oil pressure reading - the gauge simply went to max and stayed there throughout cranking session. Is this to be expected?

Doesn't appear the fuel pump or ignition are active. I'll be honest - I am not terribly strong at electrical troubleshooting. I'm wondering where you all are identifying the Pin #s? I've got the FSM and can't connect the dots! I'm looking at Sheet 12 of wiring diagrams. For example, how do I check pin 54 as suggested below (take from old thread where guy had similar problem- unfortunately no conclusion)?

Can I jump fuel pump and ignition relays to get the car to start? Anyone in Denver area with a Porsche diagnostics tool interested in coming by?

Peripheral q: the frunk and decklid release levers feel "locked". It's a 99- cable actuated. Is there some sort of locking mechanism for those?

Thanks in advance.

Here's what the garage has said:

Diagnostics does not pick up DME (ECU not responding)

Check voltage at starter - 12V

Crank key - No voltage at trigger on starter

Checked wiring diagram - System has a starter lock and MFI relays

Change relays - No difference

Connected terminal 30 & 87 on starter lock relay - This allowed engine to crank, but not fire. This side of circuit ok.

Thoughts currently - Either relay trigger circuit faulty or ECU

Power to relays, but not trigger signals. Wiring seems ok.

Check continuity of wires - All ok

Check pin for trigger switch (Pin 54 of ECU = UB switched) - This controls Air mass, MFI and DI relay, Injection relay, Oxygen sensor, Secondary airpump relay, Fuel pump (through a connecting relay)

This item is not switching - Controlled directly by ECU

Check pin 26 (Referred to as terminal 30 on wiring diagram - feeds MFI and DI relay also) - Has the required 5V switching voltage

In conclusion the ECU control from Pin 54 is causing the problem. This is the direct control for the majority of engine fuelling systems. Therefore an internal ECU fault.

Still waiting to find out the results...

Ok, at least your starter and ignition switch are working. No, oil pressure gauge should read very close to 0-1 when cranking. Most likely the oil pressure sensor is not connected or the sensor is bad (disconnect = infinite resistance = highest reading).

I'm reading the exact same wiring diagrams as you for the pins, focusing on sheets 12 and 16. You cannot just jump the fuel pump and ignition and expect the engine to fire up. There are many possibilities and unfortunately you will have to eliminate them one by one, starting with the easiest.

- Check fuse B8 and ALL the other fuses that are related to engine, DME, etc. http://forums.rennlist.com/rennforums/8516331-post7.html

- Check the fuse on the immobilizer unit.

To check the pins on the DME directly with the DME still connected, you need the DME breakout box. I would suggest checking other points to verify if the DME is even trying to fire the engine (e.g., sheet 12, M113 you see a small square merging point called "26"., which is directly connected to pin #54 of the DME. If the DME activates the fuel/ignition, this point will have 12v and so will all the lines that are connected to it. Therefore, you can check pin #7 of secondary air injection relay, which is a lot easier to access. Of course, this assumes you don't have a wiring problem so if you do see 12v with key on engine off, that means the DME is at least trying to activate the fuel/ignition.

Great, thank you for the insight. I want to learn!

I glanced at the oil pressure sensor last night -- appeared to be hooked up but I will double check.

I checked all fuses in the fuse box a couple nights ago -- all systems go. Will double check

Did not check immobilizer fuse -- will tonight.

Pin 54 check -- thank you for the explanation. That makes sense. (I obviously don't have the breakout box) Will check for voltage on the SAI relay tonight.

Stay tuned!

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I think it's still too early to conclude it's a DME-immobilizer pairing problem although it could very well be. The reason is you wrote "2. Someone had recently fiddled with DME/relay panel behind rear seats as well as the immobilizer unit under drivers seat. " That doesn't sound good.

Note the rear relay panel houses the relays to fuel injection, start lock relay, etc. All engine related http://forums.rennlist.com/rennforums/8747328-post2.html

Think about it more, forget about the SAI relay. You can just test the start lock relay again

- pin 7/86 should have 12v with key on engine off. This connects directly to DME pin 54 you wanted to test (via the "26" merge point)

- pin 2/85 should have ~0v with key on engine off. DME provides ground to this pin when it allows the starter to crank

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BTW, is the metal key blade and the key fob one piece like normal or you just put the key fob close to the ignition switch when you crank using the key blade only?

Edited by Ahsai

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Also check pin 7 of "MFI + DI" relay, which is connected to pin 26 of DME. It should have 12v always hot.

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On May 29, 2014 at 4:00 PM, Ahsai said:

BTW, is the metal key blade and the key fob one piece like normal or you just put the key fob close to the ignition switch when you crank using the key blade only?

Regular old one piece key/fob. PCB/battery is missing, but I don't believe that has any effect.

On May 29, 2014 at 5:03 PM, Ahsai said:

start lock relay

- pin 7/86 should have 12v with key on engine off. This connects directly to DME pin 54 you wanted to test (via the "26" merge point)

- pin 2/85 should have ~0v with key on engine off. DME provides ground to this pin when it allows the starter to crank

Pin 7 start lock - 11.9 V

Pin 2 start lock - 0V

On May 29, 2014 at 5:03 PM, Ahsai said:

Also check pin 7 of "MFI + DI" relay, which is connected to pin 26 of DME. It should have 12v always hot.

Pin 7 MFI + DI - 11.9V

Immobilizer fuse is fine.

I really think the ECU is the problem. 

Edited by GLIDE

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I think the pin 2 0v may not be the true ground because if it was, the start lock relay should click and you should be able to at least start the starter. Can you swap in another relay for the start lock relay? Also, can you measure the voltage between pin 7 and pin 2 (instead of measuring the pins with respect to the chassis ground) and see if you get 12v?

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I think the pin 2 0v may not be the true ground because if it was, the start lock relay should click and you should be able to at least start the starter. Can you swap in another relay for the start lock relay? Also, can you measure the voltage between pin 7 and pin 2 (instead of measuring the pins with respect to the chassis ground) and see if you get 12v?

Swapped n another relay- nothing.

Measured between 7 & 2 pins ..... 0V.

Ground issue? Just double checked + cleaned up engine ground - no change.

Car had remnants of aftermarket stereo - additional hot coming off battery to amp I'm assuming. Maybe issues arising from that?

Edited by GLIDE

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It does sound like you have issues between between the DME and the immobilizer. With that history and aftermarket add-ons, I guess anything is possible. Maybe time to visit a good indy for help.

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Would crank position signal issue shut me down like this?

 

Edited by GLIDE

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This might sound strange but are all air bags in and connected ? Another poster encountered similar issues -his steering wheel and airbag were were removed .Car thought it had been in an accident and shut itself down .

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This might sound strange but are all air bags in and connected ? Another poster encountered similar issues -his steering wheel and airbag were were removed .Car thought it had been in an accident and shut itself down .

Good point. Btw, are both DMEs non-gas? I don't think e-gas and non-egas are interchangeable.

Edited by Ahsai

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On June 1, 2014 at 3:27 PM, dcdrechsel said:

This might sound strange but are all air bags in and connected ? Another poster encountered similar issues -his steering wheel and airbag were were removed .Car thought it had been in an accident and shut itself down .

You know- I was wondering about that. 

Edited by GLIDE

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I think the durametric software could help isolate problem areas .This assumes that trouble codes are being set .Another option is to send the dme to an expert and have them go thru the unit (not sure how they handle the immobilizer -one option is to program it out ).You are dealing with a lot of unknowns and that is tough to navigate ,it would be a lot easier with a known good dme and correct maps .

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On 6/1/2014 at 3:27 PM, dcdrechsel said:

This might sound strange but are all air bags in and connected ? Another poster encountered similar issues -his steering wheel and airbag were were removed .Car thought it had been in an accident and shut itself down .

Confirmed air bag looks fine.

On 6/1/2014 at 3:27 PM, Ahsai said:

Good point. Btw, are both DMEs non-gas? I don't think e-gas and non-egas are interchangeable.

DME from 01 is egas, not sure about other one. Car is set up for egas.

On 6/1/2014 at 5:51 PM, dcdrechsel said:

I think the durametric software could help isolate problem areas .This assumes that trouble codes are being set .Another option is to send the dme to an expert and have them go thru the unit (not sure how they handle the immobilizer -one option is to program it out ).You are dealing with a lot of unknowns and that is tough to navigate ,it would be a lot easier with a known good dme and correct maps .

I don't have a durametric (yet). I think I'll have to get my hands on one - I think I've eliminated most of the low hanging fruit. Anyone have one they'd loan or any Boulder/Denver guys interested in coming by?

 

Edited by GLIDE

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You still have passenger side airbag and two door airbags to check. Your DMEs are 5 plugs, right? Can you check continuity between socket IV pin 40 and pin 2 of start lock relay? If you have continuity there, that means neither DME enables the start lock relay. One potential suspect is the connection between the RFID pick up ring on the ignition switch and the immobilizer as that's common for both DMEs, similar to missing airbags.

The crank sensor will not prohibit the starter from spinning and it's clear the start lock relay doesn't get the ground signal from the DMEs.

Agree that you need at least Durametric to narrow down the issues.

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Ok. Finally back on this project - now armed with a durametric enthusiast. I hooked up the durametric last night to see what's going on - probably biggest red flag is reporting the DME as not connected. 

Edited by GLIDE

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Ok. Finally back on this project - now armed with a durametric enthusiast. I hooked up the durametric last night to see what's going on - probably biggest red flag is reporting the DME as not connected. There had been some alarm and airbag codes as well which I cleared, but still not able to see the DME. (Also litronic are messed up but I don't think that should playma factor)

One q- this is a 99 c4. Correct me if I'm wrong but this is a 7.2 DME?

Thoughts on where to go? I have an 01 C2 which runs great. I could swap DME, alarm unit, RFID, over again- last time it appeared not to make a difference.

 

A 99 C2 would be a 5.2.2, a 99 C4 would be a 7.2 DME.  An 01 C2 would also be a 7.2 DME.

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The msg you quoted in post #3 was not for your car, right? That was for 5.2 (single plug) and both your 99 and 01 have 5-plug.

I think you can swap the 01 DME in and scan it with Durametric to see if it can connect to the DME. If not, you may want to check for continuity of the "w-lead" between the DME and the immobilizer - Plug 1/pin 3 on the DME and plug I/pin 23 of the immobilizer. If this wire is open, Durametric will be able to talk to the immobilizer but not the DME.

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