Self Diagnosis
06-01-2004, 11:04 AM
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Self Diagnosis
I believe my DME is bad. My car will not start. I can't get the check engine light to flash when I turn the ignition to the on position, and hold the gas pedal to the floor for three seconds (from the shop manuals). Does anyone out there know if Porsche enables the self diagnosis mode for the Varioram engines? It worked before on my 95' C2. I have also tried an OBDII scan tool and it comes back that everything is OK. I know that everything is not OK since I disconnected O2 Sensors and the crank position sensor just to try to get feedback.
In the event that my DME is bad, does anyone know of someone that can rebuild it as opposed to buying a new or used one? The cheapest used one (I've located so far) is $800 from LA Porsche Dismantlers.
97' Targa Tiptronic
P/N: 0 261 204 376
In the event that my DME is bad, does anyone know of someone that can rebuild it as opposed to buying a new or used one? The cheapest used one (I've located so far) is $800 from LA Porsche Dismantlers.
97' Targa Tiptronic
P/N: 0 261 204 376
06-01-2004, 11:11 AM
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Try Beckmann Technologies.
http://www.beckmanntechnologies.com/products.html
They sell and repair electronic control systems for Mercedes, they may do the same for Porsche or know who might.
http://www.beckmanntechnologies.com/products.html
They sell and repair electronic control systems for Mercedes, they may do the same for Porsche or know who might.
06-01-2004, 12:07 PM
#3
You probably have an immobilizer problem. The DME units rarely fail unless they
get water damaged. You need to use the Porsche ST2 tester to fully diagnose
the system. Also, if the car fails to crank, your problem may also be the alarm/lock
control unit.
As with any control unit, the acid test for a bad one is when another is plugged
and the car starts. When you're spending a lot of money for a control unit, the
acid test should be applied first!
get water damaged. You need to use the Porsche ST2 tester to fully diagnose
the system. Also, if the car fails to crank, your problem may also be the alarm/lock
control unit.
As with any control unit, the acid test for a bad one is when another is plugged
and the car starts. When you're spending a lot of money for a control unit, the
acid test should be applied first!
06-01-2004, 12:21 PM
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I have replaced the DME relay, the immobilizer and the alarm control unit and checked all other relays and fuses. The car cranks but I don't have spark or fuel. I have by-passed the DME relay to get the fuel pump to turn on. The fuel pump does work just the injectors are not firing.
Everything is pointing at the DME right now, (spark and fuel). Can the DME be bench tested without being in the car?
I am in the middle of the supercharger install and I am certain I sent voltage directly to the DME, resulting in a fried DME unit.
Everything is pointing at the DME right now, (spark and fuel). Can the DME be bench tested without being in the car?
I am in the middle of the supercharger install and I am certain I sent voltage directly to the DME, resulting in a fried DME unit.
06-01-2004, 12:55 PM
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Hi Dale,
Sorry to hear about your car not starting.
If it tries to crank, it's not an immobilizer problem. Since the injectors don't try to fire, it would seem to point to a DME problem. Have you checked the sensor(s) that send cam and crank position to the DME (I've not had to deal with them on my Targa, but on other cars I've had problems with camshaft or crankshaft position sensors. I presume the 993 has similar sensors.)?
As to the original question re: diagnostic mode, the '96 and later cars are all OBD-II, and don't have the CEL diagnostics like the OBD-I cars had. The '95s were all OBD-I.
Best of luck figuring it out.
-Chris
Sorry to hear about your car not starting.
If it tries to crank, it's not an immobilizer problem. Since the injectors don't try to fire, it would seem to point to a DME problem. Have you checked the sensor(s) that send cam and crank position to the DME (I've not had to deal with them on my Targa, but on other cars I've had problems with camshaft or crankshaft position sensors. I presume the 993 has similar sensors.)?
As to the original question re: diagnostic mode, the '96 and later cars are all OBD-II, and don't have the CEL diagnostics like the OBD-I cars had. The '95s were all OBD-I.
Best of luck figuring it out.
-Chris
06-01-2004, 01:05 PM
#7
"If it tries to crank, it's not an immobilizer problem."
This is not totally correct as the immobilizer may allow the car to crank but not provide
the proper activate signal to the DME over the "K" line. Also, you need to check for the
+12V inputs (pin 26 - #30, pin 56 - #15).
The simplest approach to determining the problem is to take the DME unit out and plug
it into another car.
This is not totally correct as the immobilizer may allow the car to crank but not provide
the proper activate signal to the DME over the "K" line. Also, you need to check for the
+12V inputs (pin 26 - #30, pin 56 - #15).
The simplest approach to determining the problem is to take the DME unit out and plug
it into another car.
