Alarm cause no-start?

[seningen]

Originally Posted by Smallblock454

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

5.5.2 99

I sent my DME/IMMOB/FOB to EcuDoctors -- they tested the setup and it worked fine.
I then had them modify the DME to be stand-alone.

My symptoms have not changed since I got it back. So as best I know the DME is fine and should be working in standalone mode.

So assuming the DME is working fine and the Immobilizer setup is happy -- what signals could prevent the DME from allowing the car to start?

I need to probe each one and see which is the cause?

I'm about this close to buying a second (cheap) Boxster just to have a known good unit to probe for signals on the DME.

thanks,

Mike

[Smallblock454]

Hi Mike,

in general: if the engine turns over but doesn't start because you don't have ignitions sparks i would check the hall sensors, hall sensor connectors and hall sensor wiring first. Also the DME has an engine speed sensor. To translate that from Porsche workshop manual terms to normal terms check the crankshaft and camshaft position sensors, connectors and wirings.

If the DME doesn't know the exact position of the camshaft / crankshaft in general it would try to start in a limp mode, but maybe the 5.2 with the mods doesn't.

My car has the DME 7.8, so there might be differences. When i try to start the car without a transponder the engine doesn't turn over at all.

Regards, Markus

[seningen]

Originally Posted by 911monty

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'm a EE, so I understand what you are asking.

when I am jump starting -- it's to the battery terminals -- or to the battery terminal wires.
when I am bypassing the battery -- the battery is physically unconnected to the car.
I.e. I remove the connections and connect directly to the battery terminal wires.


mike

[Turbodad]

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 door would not lock consistently before it went completely "no start"". So now all is well...the little things...sigh ....