No voltage at starter

I will continue my feeble attempt at diagnosing the problem, but thought I should ask the forum for some help in the mean time. I have a '99' 996 C2. Installed new IMS bearing and pulled the DME relay to circulate oil and not start car. Of couse this didn't allow me to start car so re-installed relay and started car for split second. Then re started for another short second. This was my way of circulating some oil before extended running of engine. Not the smartest thing to do as now my 911 won't run at all and the starter isn't getting any voltage to the solenoid. I don't have a scan tool, but I do have a voltage meter. So I thought I noticed a test procedure for the DME relay, but now can't locate. If anyone has an idea what might be the problem with my ignition system please respond to this thread. I'm alittle stumped. Don't know if imobilizer is the culprit or somethiig easier to identify. Thanks in advaance for any and all replies. Alan

First I would try to reset everything by removing the negative battery lead for 10 minutes. Then reconnect and see if it starts. Second, swap the DME relay for another one such as the spoiler relay and see if it works. Also, check the fuses, although that would affect the DME more than the main voltage to the starter solenoid.

Do you have 12V at the jumper terminal in the engine bay? Also try swapping out the start/lock relay with another one.

DBJoe, Thanks for the reply. I've tried all the options you posted, but nothing seems to work. The terminal 50 at the back of the starter dosen't see any voltage. I didn't see any other relay that resembles starter relay that sits behind the DME one. Don't know if a Durametric tool would diagnose the problem. Haven't got one of those anyway. Will probably have to push car onto car hauler and transport two hours up to Grand Rapids so dealership can plug thier scan tool into OBD socket. Thats the dealership that is the closest one to where I live. They are the ones that programmed my new key to the old car. Will keep you posted if anyone else comes up with a possible fix.

So the atarter does not turn at all when you crank? Have you tried another key? Jumped the clutch start lock microswitch?

Yes Starter does nothing when turning the key. All dash lights illuminate everything else seems to work just no noise from the starter. Yes I tried my old key that came with the car, but same result. I did jump the two wires that lead to the switch at the clutch pedal. No go. Strange that after four months of not running the car, the engine started, I shut it off, started again, then nothing. The only other outside force was that I removed then replaced the DME relay that resides behind the back seats. The car started initially, after I replaced the relay, but would not start with relay removed. I think LN engineering advocates removing this relay to circulate oil without engine firing. Sounded like a good idea at the time.Now I would not recommend this to anyone replaceing thier IMS bearing. If anyone has had this same or similar problem or has a possible fix, please post a comment or point me in the right direction for trouble shooting. Thanks as always

Look at post #2 by Joe. You can swap the engine comp fan relay with the DME relay amd see if that fixes your problem. The two relays should be identical.

Ahsai, Thanks for the response. I will have another look at the relays, but have swapped out the DME a couple of times. Didn't find one that matched the starter relay. Will look again for a match to that one as well. I may be looking in the wrong place. I have replaced a number of wear items on that car and might have pinched or pulled on a bundle of wires tha carry voltage to the solenoid. I removed the AC comp. and had to lift the bundle of wires that route around the positive jumper terminal to gain space to put comp. back. Also replaced oil fill tube and had to swap wire bundle locations so I could rotate and remove alternator. The starter wireing bundle was placed under the alternator bundle so it was taking up too much space. I've had some rodent damage to the AC comp. wiring when I first got the car as the clutch power lead had been chewed through. Will look at all that and see if anything looks suspicious. Will let you know what I find.

You didn't say whether you had 12V at the jumper terminal in the engine bay, or not. The main 12V from the battery is routed directly to the engine bay jumper terminal and then the Y-cable goes from there to the main terminal on the starter. The starter solenoid circuit goes through the power distribution box in the passenger footwell. Those are 50/80 amp fusible links in the power distribution box. The main 12V power distribution system is here You should have full 12V at each connection point

Yes your right. I forgot to mention that I do have voltage at the jumper terminal. Around 12.6 volts. Nothing shows up at the solenoid on the back of the starter though. I checked the fuses in the box at footwell. Nothing blown that I could see. I think that the solenoid circuit is bundled with the main power cable to the starter isn't it? I'm really not sure how that ignition wire is routed. Think I remember both wires routed to starter inside cloth wraped bundle laying on top of engine, behind throttle body. Please correct me if I'm wrong.

If you have 12V at the jumper terminal then the high amperage leads to the starter motor are okay. Your problem is in the starting circuit - electrical part of the ignition switch, clutch interlock, power distribution box, starter relay in relay support, engine bay main electrical connectors, to starter solenoid. You are correct that the starter solenoid wire is bundled with the main leads to the starter motor, but it gets there via the above route.

Also understand that the following conditions must be met in order to crank - immobilzer reads the key and signals the DME that it is the correct key, then the DME enables the starting circuit. If the correct conditions are not met, no crank and the starting circuit is disabled. Once again, check fuses for the immobilizer and engine electrics as well.

Joe has already provided a lot of grreat info. Have you checked fuses C1 to C4 and E1?

Hey Ahsai and Joe, I appologize for not getting back to you sooner. Busy day I guess. Anyway I will check those fuses and get back to you as to what I have found. I have taken the drivers seat loose so as to gain access to the imobilizer and the 15 amp fuse is fine. I called the Porsche dealership where I got my old car coded to my new key. The service guy said he couldn't diagnose over the phone. So I asked if worse comes to worst can I jump between the 12 volt teminal on back of starter and energize solenoid without harming any circiutry, He said he didn't know. Do you guys think that wil work if all else fails? Thanks again for your responses and I will check those fuses.

DBJoe, Sorry about being gone all day and not getting back to you. I really appreciate the help. I am not sure where the main 12V distribution box is located. Your pictures would'nt come through. I noticed a relay panel next to clutch pedal under dash. Is that the location of the panel? I should know this,but don't. Will look through manual and try to find the panel. Thanks

DBJoe, Sorry about being gone all day and not getting back to you. I really appreciate the help. I am not sure where the main 12V distribution box is located. Your pictures would'nt come through. I noticed a relay panel next to clutch pedal under dash. Is that the location of the panel? I should know this,but don't. Will look through manual and try to find the panel. I re-read your post via my phone and was able to view your excellent electrical schematics. Also learned that the distribution box is located in the passenger footwell. Since it is getting late, I will check voltage tomorrow morning. Thanks again

Power distribution box is located behind the carpet on the firewall in the passenger footwell. Yes, you can apply 12V to the starter solenoid so it will kick in the starter, however, that is pretty difficult to do with all the stuff in the way. And working a live wire back in there doesn't sound like a very good idea. Also, it has to be just a momentary contact to engage the solenoid and immediately removed once the engine runs. I really would not recommend doing this just to get the engine running. I think it is better to determine where your problem lies and fix it.

DBJoe, Okay I will try to trouble shoot and repair before doing anything risky. Just thought that if I needed a shop to hook up a scan tool I would rather drive the car instead of putting on car hauler. Anyways....I accessed the distribution panel and found all fusible links to be intact and working. I checked the relay panel behind rear seat as well and when ignition is in start position, working on start relay, I have no power at any of the blade points on relay holder. I'm guessing that my ignition problem would be somewhere before the start relay and not after. I checked the fuse at the immobilizer and that was fine, don't know if there is another one feeding that part or not. Will check. I'm thinking the final piece of the puzzle is the ignition switch. Do you have any insight as to how to remove and test? Thanks for any reply

Quotes source post: 14992786

Check all of these fuses first, then move on to the electrical part of the ignition switch. You have to contort yourself under the dash to loosen two small screws on the ignition switch to remove the electrical part of the switch. Good work so far. Seems like you are getting close.

Okay, I will double check the fuses listed. Then get contorted.

Here is a thread about the same issues. Thanks to Ahsai for Post 46 and the picture! https://rennlist.com/forums/996-foru...olenoid-4.html Here is the starting circuit diagram:

DBjoe, Here is the latest from my side of this. I checked those five fuses and they are not blown. I removed the back off the ignition switch and jumped from 30/1 terminal to the 50 terminal. Pulled the starter relay and jumpered between 30 and 87 the starter turned the engine over like it used to do. The engine didn't fire up probably because the DME relay isn't pulling in. Also the starter relay had to be jumpered to work. The 30/2 red and white wire didn' carry any voltage not sure why as they seem to be paired together in the wireing diagram. Does anyone out there know what my next step should be? I'm not real astute at reading these wiring diagrams.

not sure if this will help ..............at the starter relay -pin 3 12 volts from ignition switch when start position engaged .Please note you have to turn key off on every test cycle .Pin2 is ground from dme -Pin7 is 12 volts from the mfi relay .If I had to guess you are not getting the dme ground which leads back to the immobilizer

Thanks for the input......A couple of questions: Not having a ground is not good. Does that mean immobilizer is faulty? Or is the immobilizer not getting the signal from my key? Also while checking pin three while turning key I had no voltage. I had to jumper between back of ignition switch to pin 50 to carry voltage to start relay. What is the MFI relay? Thanks for any reply

The dme ground activates the relay which completes the circuit for the ignition switch yellow wire to connect to the yellow starter motor solenoid wire .The mfi relay is adjacent to the start relay -please refer to a earlier post for diagram .If you do not have 12 volts pin 7 check all the other fuses .If the dme ground is open with the ignition key in the run position -likely in the immobilizer circuit .The easiest way to test this stuff is to put temporary leads ( wire ) in the relay socket and reinsert the relay .Pin 3 will not have voltage if the dme ground is open or there is not 12 volts at pin 7 .

forget last pin 3 comment

Thanks again for getting back to me on this. I will use small wires then plug relays back into sockets to gain insight as to what is going on at relay bases. I'll take a continuity reading at pin 2. Will probably take a little bit of time to check . Will report back tomorrow as to what I find. I can check all other fuses as well.

Quotes source post: 14995330

Sounds like the ignition switch. If you turn the key to the crank position while simutaneously apply power to the starter solenoid via the start lock relay (unplugged) pin 87, the engine should fire up. ​​​The key needs to be inserted and stay at the crank position for the immobilizer to detect the RFID pill inside the key fob.

When you checked the fuses did you use the ohm meter or just a visual ?

Ahsai, Thanks for your input...Sounds like I need to reattach the wiring plug back onto the ignition switch. Then find a way to energize blade point 87. The reason I think that I have to reattach wires is that the orange wire from the ignition switch looks to activate something in the signal transponder. At least that is what the wiring diagram looks like. Will let you know if this works.

Yes I just did a visual. Except at number E1 fuse. I remember in the air compressor industry that a bad fuse could show continuity but didn't necessarily conduct electricity, but if you think I should ohm out these fuses I will do that.

Yes I just did a visual. Except at number E1 fuse. I remember in the air compressor industry that a bad fuse could show continuity but didn't necessarily conduct electricity, but if you think I should ohm out these fuses I will do that. Those fuses, in compreessors, were of a different variety as I remember them. Kinda like small buss fuses. I think they contained a powder inside them which would explain the ohm reading when faulty. These fuses are entirely diffrent and I will ohm them out.

Here is the ignition switch circuits and contacts. So what you are saying is when you jump 30 to 50 on the ignition switch, and 30 to 87 on the starter relay, the starter works (spins), and the reason the engine did not run is because you still have the DME relay out. So you need to do one or the other, i.e., jump the 30 to 87 and try the ignition switch. If it doesn't work...ignition switch. Or do not jump 30 and 87 and jump 30 to 50 on the ignition switch. If it doesn't work, starter relay. Make sure you have the key in the ignition switch so the immobilizer can read it. And I would put the DME relay back in to eliminate one more thing. I know all this was an attempt to run the engine with the starter and not actually start it. But everything works in concert, ignition key, immobilizer, DME, ignition switch, starter relay, etc.

I know earlier it was suggested to remove the start relay and move one of the other relays in that spot. But I thought I would check the part numbers on that, and I see that the starter relay has it's own unique part number unlike the other relays. S1 141951253B Relay - DME S2 141951253B Relay ignition S3 99661510200 Relay Spoiler S4 99965701890 Relay Air Conditioner S5 99661511200 Relay Rear Window Heating S7 99661511000 Relay Starter S8 141951253B Relay Blower Engine Compartment S9 99661510200 Relay Spoiler S10 99361511501 Relay Secondary Pump

I think you are chasing two problems -starter won't engage and engine died .Without 12 volts on pin7 of the start relay I don't believe engine will run .As far as starter if there isn't 12 volts on yellow wire from ignition switch in start mode that points to the switch . If it were me I would check continuity on all related fuses .Tedious but there is a reason pin 7 isn't getting voltage

Quotes source post: 14996040

Wait.....30/1 has 12V but 30/2 does not? See ignition switch wiring. That doesn't make sense. They both should have 12V on them. Those are the main 12V feeds for the ignition switch ACC position 1, engine running position 2 and starting position 3. Both should have 12V unless something is broken inside the electrical switch. What does happen when you are in Position 1? Do all the accessories power up..radio, gauges, etc.? You should have 12V at all points on the back of the switch in Position 2, except for 50, the start position.

So all of those quick starts/shut offs may have broken the switch? Sure would make sense to replace the frequently troublesome switch before spending too many more hours folded up under the dash.

Jim, Thaks for looking out for my well being. Yoy may be right I may just have a faulty ignition switch. I took readings at all the pin points at the start relay and am about to sort and post to the community. Hopefully someone can tell me where me and my car stand. Alan

First off thanks to evereyone who has guided me through this ignition trouble of mine. Here is what I have found of late: I started out employing Ahsai's advice and energizing Blade point 87, pin #5 with 12 volts. What happened was the engine turned over, but did not start as hoped. I had reattached wire terminal to back of ignition swicth to make sure all systems were being energized as much as possible. Then used key with pill inside to hopefully signal immobliizer into action. Again no-go. I next ohmed all the fuses in panel and found none to be open. Then opted to go with DCDreschsel's idea of inserting small wires along pins in both the Start relay and also the MFI relay. Here are the findings.. Starter Relay: Pin 5, location 87 0 volts, Pin7 location 86 12.49 volts, Pin2 location 85 12.06 volts and Pin3 location 30 12.52 volts MFI relay: location 87 12.48 volts, location 86 12.48 volts, location 85 1.04 volts, location 30 12.47 volts. These readings weere taken with clutch pedal depressed and key in start position. I know DBJoe was wondering about voltage or the lack of at the ignition terminal location30/1 and30/2. I can't explain why therewas no voltage at one wire and 12 at the other without replacing wire terminal tl back of switch and turnign key to run position while takeing a reading via insereted pins into said conductors, but I can do that tomorrow if needs be. Pease let me know what you guys think of these findings....Thanks

ok-pin 2 with key on should be the dme ground signal - with meter probes on pins 2 and 3 you should get 12 volts .You can also test pin 2 to ground using the ohm function .If there is no dme ground signal it gets complicated .The bothersome part is that it abruptly stopped -either a short or bad connection .You mentioned that a mouse had been in there ,are there any signs that a previous owner had tuned/hacked the wiring ?The question is based on the 30/1 and 30/2 inconsistencies .There is a firm in Florida that specializes in Porsche dme's and related stuff .I would call them -someone on this forum will have their contact info -and ask them what they suggest.

Is there any chance you are not pushing the clutch pedal all the way in, or the clutch switch is broken? I think that would give you the same symptoms.

Quotes source post: 14998858

Eliminated at post #6.

OP, can you revert everything back to how they were before except with the start lock relay unplugged? Then check pin 30 of the start lock relay socket. It should get 12v as soon as you turn the key to the crank postion. If not, it's likely the ignition switch.

Ahsai- in his last test he had 12 volts at pin 30

One more idea .........put a test lead on the dme relay pin 87 and verify it is powering the dme

bad post above you already did that

dcdrechsel et al, Again I appreciate all the responses. In regards to pins two and three of the starter relay, I unfortunately get 12 volts at each location. I ohmed pin two to see if it gets a ground signal, but there is residual voltage when I turn off ignition then an ohm reading of 34.7 resistance. Later when I checked the meter would go blank when checking for ohms as there was probably too much voltage stored at that pin or that pins source. Not sure what all that means except I don't think pin2 should have a voltage reading. That may mean the tiny holding coil inside relay is defective and bleeding electricity over to the ground side, but not sure. I don't have another relay to check this out. There are signs of some mischief going on under drivers seat. There are two ground studs under there with brown wires running to them. They look to be spliced then taped up by someone other than the factory. There is also a replacement radio and some sort of microphone hanging by mirror and a usb plug coming out from under the console. Thats about all I can tell you. If anyone has that Florida firms name and number that would be great. I also don't have a wiring diagram of that MFI relay and circuit. Thanks as always..

Here is what we should have: 12V from power distribution box to 30/1 and 30/2 on the ignition switch (these should be hot all the time), then when ignition switch is moved to start, 12V at Pin 50. In the start position, all pins on the back of the ignition switch should have 12V at this point. That 12V from Pin 50 is passed to Pin 3/Blade 30 on the starter relay. That kicks the starter relay to pass 12V to Pin 5/Blade 87. In the start position, all pins/blades on the starter relay should have 12V at this point. From your testing, what we don't have is 12V on 30/2 at the ignition switch at all, and no voltage at Pin 5/Blade 87 from the starter relay when in the start position. Bad starter relay, since the Pin 3/Blade 30 is getting 12V from the ignition switch but not passing it to Pin 5/Blade 87. You said when you jumper Pin 3/Blade 87 to Pin 5/Blade 87 the starter motor engages. I would start by replacing the starter relay. Knowing you have a good one in there eliminates that problem. Then go about trying to figure out why 30/2 on the ignition switch does not have power. It should be hot all the time. Starter Relay: Pin 5, location 87 0 volts, Pin7 location 86 12.49 volts, Pin2 location 85 12.06 volts and Pin3 location 30 12.52 volts MFI relay: location 87 12.48 volts, location 86 12.48 volts, location 85 1.04 volts, location 30 12.47 volts. These readings were taken with clutch pedal depressed and key in start position.

Okay, I will check to see the reason I have no power at 30/2 location. Does anyone know where the junction no. 119 is located in the car? That may be a good place to start when diagnosing that problem. I will probably order a start relay as that does not seem to transfer any power to tereminal 87. I do here an audible click back there when turning key to start position. Will employ some help to turn ignition key while I sit in back and sort out which relay is clicking. Will let you know what I find....

Here are the other relays...they pretty much work the same way...Power supplied to Pin 3 and activates relay to Pin 5. However, keep in mind these other relays stay powered, unlike the starter relay that once the engine is running, no more power is supplied to Pin 3 when the ignition switch is moved from start to run.

119 - see the ignition switch diagram. You might have to trace back the 30/1 and 30/2 red/white wires in the wiring loom. Also, the 119 junction...well...see the one red/white wire going to the right? That goes to the Turn Signal/Dimmer switch. One other stupid thought I have is...why have 2 main power wires leading to the ignition switch..30/1 and 30/2 that power everything from the ignition switch? Amperage. It takes a lot of amperage to throw the starter relay and power everything up, and by not having any 12V on 30/2...maybe, just maybe not enough amperage is being passed by the ignition switch to the starter relay after power is supplied every where else. Hmmmm...

Ignition circuit and wires a little zoomed out. You can see what I am referring to above. The main wire from the power distribution box is 6 gauge, and then drops to two 4 gauge wires to the ignition switch. When the ignition switch is in the start position, it sends 12V through a 4 gauge wire (Pin 50) to the starter relay. The wire to the turn signal/dimmer is a 2.5 gauge red/white wire.

to test start relay ground pin 2 and the key start will probably work -you might also make sure voltage is going from ignition switch to the signal transformer

Quotes source post: 14999480

Sorry if I missed it but I thought that's AFTER he jumped the ignition switch?

Quotes source post: 15000010

Good point to remember! Most of the switches/relays and so on do NOT provide +12V, but do provide a path to ground to complete the circuit. So the +12V is already there and then a switch provides a path to ground. It is interesting. In this case, the ignition switch is not providing a ground, but sending 12V to everything to power up.

To everyone who helped me in trying to sort out my starting problems, First off I'm sorry for taking so long to get back to all of those that took an interest in my no start situation. I had really no new news to add as I thought I would take a brake from trouble shooting. I think DBJoe and everyone else were on the right track when trying to run down the cause of either no voltage or no ground at certain terminals. Instead of trying to test all the different teminals, I instead finally took DBJoe's advice and went ahead and bought an ignition switch and a start/lock relay. After taking car to an Indy, I decided to tackle the job of installing new switch on my own as the shop didn't have time to do so when I asked. First I reconnected the ECU that the shop had disconnected. I then replaced the ignition switch and tried to start the car. Nothing happened. As a last resort I installed a new start relay. I was pleasantly suprised when the engine turned over. Took a few long seconds for the engine to fire, but it finally did. I let the engine idle as I fastened drivers seat back to floor and relaced relay and ECU shelf to thier location. Then happily drove away. Thanks for all the help...Jumpy

Glad to hear you got it sorted. I remember some of your tests pointed to the ignition switch and some to the relay. At least now you don't have to worry aboit those two for a long time to come.

Thanks..for the help. Looking forward to some warm weather driving. As a side note I used your instructions on replacing the coolant, water pump and thermostat while the car was stored over the long winter months here in Michigan.

Quotes source post: 15030712

Glad to hear those instructions were useful

Happy Motoring and thanks for the feedback

Hi, sorry, I'm Italian, what is "start lock relay"? Relay starter 996 615 110 00 or ignition relay 141 951 253 B? Thanks in advance. BR. Pat