Alarm cause no-start?
 

I have a Spec Boxster with an odd no-start issue. (cranks but no fire)

I have DME power, but as best I can tell I do not have fuel or spark.

If the immobilizer/dme thinks the car has had an alarm tripped, could it trigger a no start?

If it has -- is there anyway to query the alarm status via the DME?

I have a durametric.

I do not have an alarm module (I think).

I have replaced the DME/IMMOB/KEY with a non-alarm IMMOB version (531? I think),
but thats more by happenstance of the replacement set I acquired.

It didn't change the behavior.


If it matters -- I can start the car if I jump it from another vehicle, as long as I remove the battery from the system (and yes I've gone through 3 batteries).


I'm about at wits end -- and wanted to inquire about how the alarm might come into play -- and/or how it can be observed to rule that out.

thanks,

Mike

Where are you making the connections when jump starting? The neg post of the battery or to ground on the car? You could be making a circuit to ground that is open by the DME when bypassing the battery.

I ask because a lot of electronics make connection to ground to complete the circuit. Maybe a ground wire from battery to jump point?

I connect to the lead which would be connected to the battery ground when
jumping. I.e. I pull the lead off the battery and jump from there (although I have also clamped onto the body ground post with the same results).

I replaced the ground lead with no difference in behavior.

The positive jumper cable connects to the positive battery post.

Mike

I can understand your frustration. So to be clear.

Your car does not ever run (does crank) with battery in system.

Remove battery from system by removing neg clamp from batt post and jump using either the negative clamp or cable connection point on car, using what? a running car or another battery? (13.8 volts vs 12v.)? Either way the alarm module is still in circuit. But car runs every time?

This is a weird one.

Yes you understand it correctly --

If I use a jump pack, another battery, basically anything but a running car -- it will crank all day -- but not start. NOTE: this was not the case prior to my last track weekend. I did have a similar behavior once before last year, but I charged the battery and I didn't have the problem again. I subsequently replaced the battery and ran an entire race weekend last spring. Fired up many times over the summer, and ran two sessions this past DE weekend. I left the marker lights on and thought I had just run the battery down for my last session of the day, but that's when this mystery mode took over. Charged the battery, no dice. I've run across a case where you kill a battery so badly it creates a dead cell and won't allow you to jump it -- so thats when I did the jump without the battery and determined
it would run. I subsequently have tried 3 different batteries -- including a 1000CA AGM monster -- just to rule out any dumb battery issues.

So summary,
If I hook it up through jumper cables, it will turn ever so slowly, and on the 3rd or 4th revolution -- it fires right up and will run all day long. With or without the battery.
Note the SPB alternator drives ~14.2v.
Anything else, crank but no fire.

I have swapped out the DME/Immob/Key/Signal Transformer/Transponder Coil for a good set -- and no dice.
I've bypassed the kill switch, ignition toggle switch relay.

I have a new ignition switch in hand -- will test it this weekend -- but it ohms out fine, I also have a ignition toggle switch relay on order.

Yes it is a weird one.

I have crawled through the schematics and created this summary page for the main relays of interest.

I have access to the back of the trunk relays -- so I will be probing them this weekend. This will at least let me know if the DME is creating the proper ground paths for the MFI and Start Lock.

I will also be verifying as best I can to see how my SPB is wired relative to this diagram.

I know the DME is getting voltage as the MAF 12v and 5v references are correct.

http://986forum.com/forums/uploads02...1538673106.jpg


Whenever I figure this out -- I will have way more intimate knowledge of the wiring and workings of my SPB than I ever really cared to know.

Mike, Since your car is cranking slowly but can run, I would think you have a power delivery issue either due to too small cables or weak ground. Does the car always crank slowly? This can be an issue since the starter is consuming all the electrical power the resulting voltage drop is insufficient to supply the DME to fire users like the fuel injectors, fuel pump and plug coils.

My suggestion would be to temporarily run direct cables from ground post to the engine block and one to the body near the DME. If still no go then a positive jumper directly to the starter then test.

If the alarm system is activated the car won't start.

What MY is your car (or car setup, because it seems to be no stock) and what DME version and immo system does you car have?

Regards, Markus

It is a 1999, all spec boxster run the 5.2.2 (97-99) DME (I think thats the number)
I have used a M535 (which is stock to my SPB) and a M531 immobilizer (with the appropriate key/dme that pairs with it)


Clarification:

Via battery or jumped -- she cranks fine -- to the point of 40psi of oil pressure -- cranking is not the issue.

It's only when Amps are limited by the jumper cables does the cranking become very slow -- but it seems as if the higher voltage is sufficient to make the difference because it fires -- at least thats the only way I can make sense of things.

I have checked both positive and negative cables. Even while cranking, I only see a 400mv drop from battery to starter (in battery mode) and a total drop of about 1.5V total (due to load on battery). This seems to be fairly typical.

Note when it does start -- it drops through the jumper cables to about 8.5v! But somehow it seems as if the initial voltage is the key -- but I don't know.

thanks for the suggestions tho -- I might have missed something... (ok clearly I have or I would have figured it out by now)


Mike

I think the key transponder isn't recognized by the immo system and the alarm system is active.

If you have a second key or more keys for the car i would try to use them. Also it would be interesting if the key fob works.

Can be the transponder itself, the antenna that receives the keys transponder signal or the wiring from the antenna to the alarm control module.

That would mean ignition and starter are blocked by the immo system. In that case in general if you start the car via hot wiring the car will start by engine will die shortely after it was started or it won't start – depends on the circumstances. And if you don't hot wire the starter, there will be ignition but you can't start the engine / engine won't turn over when you turn the ignition key one step further.

Problem is you would need a PST to check the alarm ecu and check what is wrong. Durametric doesn't give you access to this module.

Regards, Markus

Sorry if I'm confused, but you're saying that the car WILL start but only if jumped...and that you've tried 3 different batteries in the car, but car will not start if battery is directly connected? If that's the case, what happens if you install the battery from the jump in the car? I know this seems overly obvious, but I'd assume it would start...then you could go about trying to find the point of issue.

If car does start via jump (connected at battery), I'd rule out immobilizer issues (as well as other components in your schematic) and start thinking about wiring and connections. My fist thought is a braided wire that a few strands have broken free...thinking that an x-gauge wire can handle x-amps, but if at the point of connection the "strands" are not all making contact, the x-gauge wire is effectively 1/10th x-gauge and thus not sufficient.

I know you have done your homework and are way down the diagnostic path, but perhaps you should try to "restart" your approach and clear any potential misconceptions. I know I am the biggest victim of "thinking"...many (many, many) times I have a hypothesis stuck in my head and spend far too much time trying to prove I'm right rather than taking a few steps back and starting from scratch...even then I wouldn't admit I was wrong, just not right enough. ;)

I'm going to suggest the starter itself.

I am also going to offer to send you a known good working matched set of ECU/IMU/Key Fob to swap in and see if that makes any difference.

I grabbed a (supposedly) good ECU/IMU/Key Fob from Woody, but I'll happily pay shipping both ways for a second set just in case.

What would the symptom be with the Starter -- I did measure voltage drop from
the battery to the starter at ~430mv during cranking, with a total drop from ~12.5v to about 11v. Both seem inline with what I've been hearing.

This weekend I'm going to measure the voltages across all pins of the relays posted.

I'm sure I'm going to find its something simple -- major DOH moment, but I'll be thrilled when that happens.

I'm already missing Hallet this weekend and I have a 5 weeks until Cresson.

Mike

Update please, I am having the same issue, single click of the starter, will not crank. I am in San Antonio.

OP: that is a strange one. If it starts with a boost ignore all electronics and concentrate on looking for a bad ground that is causing the voltage to drop when just off a battery. I could be wrong but I would guess a running car (boost vehicle) wlll deliver more than 13v because the alternator should be delivering 13-14. So if it starts with more volts then something, when just off the battery, is dropping a few volts and maybe not energizing the key pill. With a boost vehicle you will have more than 12v so you can afford to lose 1-2. With no boost vehicle you are getting less than 12v for some reason. Maybe to test this theory you can get some volts back on startup by pulling various fuses - radio - daytime running lights, interior lights, etc. And see if it starts.

Found this on the Interwebby: Fully charged automotive batteries should measure at 12.6 volts or above. When the engine is running, this measurement should be 13.7 to 14.7 volts.

That’s just an ordinary time for a new battery issue. If you put in a new battery and it does that, time for a new starter.

Installed a new battery it started. let it sit for a few minutes because the AOS tube had come loose and it would not start. Changed the starter last week. Checked relays and fuses. I installed a matched set i got a few years ago with a swap engine and no joy...


There is an electrical connector in a black plastic box in the engine compartment. I would call it a "ground" but I believe it is a positive terminal. When I turned the key and wiggled the cable the car started. I sprayed the connection/nut with a little battery cleaner, loosened/tightened the nut and the car works perfectly after eight months. Also I did have a warning sign in that the gas cap would not lock consistently before it went completely "no start"". So now all is well...the little things...sigh ....

My case is not starter related (well at least in the normal sense).

My car is a race car and is wired to crank even with the DME removed -- i.e. where the DME pin 66 would drive the start activation lock with VSS, my relay is hardwired to ground on pin 85.


That being said -- I am still working on this problem (abet with some interruptions caused by life).


What I know. (lets ignore the will start with jumper voltage --- that hasn't worked lately).


No fuel pressure, No gnd on pin 85 from DME (pin 63). Fuel pump is fine as I have a Fuel pump run switch which turns on fuel pump, and I get good pressure.
Connectivity from pin 85 to DME pin 63.

No fuel injector firing (noid light doesn't turn on)

12v on MAF pin
5v on MAF pin (low volt)

Sent DME off to be tested. It tested fine, but I had the Immob requirement removed anyways. (www.ecudoctors.com)

CPS provides a good signal and missing tooth and signs of decent cranking speed.

Not sure if I have spark -- difficult to test. I have a magnetic spark detector -- but I haven't
had it running to observe it working -- so I don't know if I have no spark -- or a user error
with the spark detector.


I have ~0.4v drop from battery through all cables to starter when cranking -- which seems reasonable.

Battery voltage while cranking remains >10v.


Next steps -- although they are more difficult to do because I'm not sure how to monitor the DME pins with the DME connected.

DME
Observe Pin 63 (which I can get at the Fuel Pump Relay)
Observe Pin 66 (which would be at the Start Lock Relay, but is not since it's connected to ground)

Observe Pin 12 to see if the DME is being sent a shutdown signal (or lack of OK signal)

Check to see where the Clutch interlock signal goes -- I can't find it on my wiring diagram.

I know normally it won't let the starter engage -- but I'm not sure the exact mechanism.


QUESTIONS:

What is the normal operation of pins 63 and 66?

Does pin 12 shutdown the DME == and if so what is the normal "OK" value?

Where and how does the clutch interlock signal enter the system?


I'm about this close to buying a cheap POS Boxster -- just to have a known good reference.


thanks,

Mike

Found pin 66 in the wiring harness that was taped up as my spec boxster is weed for push to start. This is the pin that should connect to hand to let the starter relay engage.

It’s reading 12v as is pin 63 which is the fuel pump relay.

I had the dme checked and it’s good.
My dme has also been modified to provide its own immob code.

What are the inputs required to allow the dme to be happy?

Something is telling my dme not not allow the car to start.

Thx,

Mike

M531 is an immobilizer unit without remote control function.

M534 and M535 do have additional remote control functions.

All of them use a transponder to activate the DME. There is no system that deactivates the immobilizer without transponder.

By the way - which DME version do you use?

Regards, Markus