Please confirm or disagree... Please!

[JebLacey]

Ok... I think I have conclusively determined that my problem is my DME intermittantly failing, as some of you have speculated. it is covered under the 8/80 emmisions warrenty, and the car is going to Tallahassee on tuesday. However, I am nervous, because with the holidays, bank account is looking rough. If they determine its not the DME, I am screwed. Please review my determination, and let me know if i missed anything.

99 Box, 63K miles, Tip.

Symptoms: No start condition, CANBUS malfunction, no CEL test at ignition. INTERMITTANT problem.

- Cranks, but no fuel pump start, no CEL, ect.

My determination is that the DME is intermittantly failing, causing a CANBUS timeout when the car is in motion. If it fails to start after a successful, driving cycle, the CANBUS failure does not occur. The CANBUS failure occurs because the DME is sending power to the Unit, but then when it goes out, the TCU still has power but no signal for a second (all it takes is a faulure of a fraction of a second to cause the timeout).

The CEL gets signal and power from pin 8 of the DME. There are only two possible causes for a no CEL condition at accessory... a failure at the bulb or wiring, or no signal from the DME. Since the condtion is always coupled with a no-start (ie other failures of units getting their power form the dme), i know that the DME is not sending the signal to its periphials.

The DME gains power from the battery through fuse C1, through DME relay 1, to pins 26 and 27 of the harness. Power is constant on these pins, and has been verified w/ multimeter. No problem to this point.

The ignition non-constant power comes through B8, directly to pin 56 (terminal 15) when the ignition is on. This power is also making it to the DME. The grounds at GP 8 and 9 have been tested, and are working as required.

So essentially, the DME recieves all the power that it requires, but when the problem occurs, it does not send that power to the units that require it. The fuel pump relay, for example, does not recieve juice when the DME is down.

No codes except the P0600 can be read (DTC 100-101). This is because the DME is not on to record any faults. The P0600 (DTC 100-101) only shows when the car is on and running before and during the faulure, so the TCU has a moment to store the DTC.

Please let me know if anyone disagrees with my conclusion before I screw myself over in tallahassee...

[WARDHOG]

Ok... I think I have conclusively determined that my problem is my DME intermittantly failing, as some of you have speculated. it is covered under the 8/80 emmisions warrenty, and the car is going to Tallahassee on tuesday. However, I am nervous, because with the holidays, bank account is looking rough. If they determine its not the DME, I am screwed. Please review my determination, and let me know if i missed anything.

99 Box, 63K miles, Tip.

Symptoms: No start condition, CANBUS malfunction, no CEL test at ignition. INTERMITTANT problem.

- Cranks, but no fuel pump start, no CEL, ect.

My determination is that the DME is intermittantly failing, causing a CANBUS timeout when the car is in motion. If it fails to start after a successful, driving cycle, the CANBUS failure does not occur. The CANBUS failure occurs because the DME is sending power to the Unit, but then when it goes out, the TCU still has power but no signal for a second (all it takes is a faulure of a fraction of a second to cause the timeout).

The CEL gets signal and power from pin 8 of the DME. There are only two possible causes for a no CEL condition at accessory... a failure at the bulb or wiring, or no signal from the DME. Since the condtion is always coupled with a no-start (ie other failures of units getting their power form the dme), i know that the DME is not sending the signal to its periphials.

The DME gains power from the battery through fuse C1, through DME relay 1, to pins 26 and 27 of the harness. Power is constant on these pins, and has been verified w/ multimeter. No problem to this point.

The ignition non-constant power comes through B8, directly to pin 56 (terminal 15) when the ignition is on. This power is also making it to the DME. The grounds at GP 8 and 9 have been tested, and are working as required.

So essentially, the DME recieves all the power that it requires, but when the problem occurs, it does not send that power to the units that require it. The fuel pump relay, for example, does not recieve juice when the DME is down.

No codes except the P0600 can be read (DTC 100-101). This is because the DME is not on to record any faults. The P0600 (DTC 100-101) only shows when the car is on and running before and during the faulure, so the TCU has a moment to store the DTC.

Please let me know if anyone disagrees with my conclusion before I screw myself over in tallahassee...

How did you determine all of this? Sounds like you did some troubleshooting and are stuck for a resolution. You mention that the fuel pump relay may have no power. Have you confirmed that by checking at the socket and if you did, did you remove the relay to check for power to energize the relay? Are you checking at the fuel pump to confirm you have no power and that is why you think the relay is not getting power? I assume you know that there is two parts of the relay you must check to determine you have a bad relay. The first is the power to energize the coil and the other is the contacts afflicted in the circuit of concern. Of course, you could just slap in a known good relay and that would take the relay in question out of the picture. Last but least, have you let the dealer connect the car to the tester? That would only cost you the cost of labor, if that.

Edited December 23, 2005 by WARDHOG

[JebLacey]

Thanks for the reply, Wardhog.

Yes... I have checked the relays for function... its not just the fuel pump that does not get power... its everything that comes off the DME for its power or signal to start. At first, I thought it was the DME Relay, but that was eliminated due to the power in Pin 26 or 27 (one goes through the relay, the other is a straight shot from fuse C1) of the DME connnector.

[WARDHOG]

Thanks for the reply, Wardhog.

Yes... I have checked the relays for function... its not just the fuel pump that does not get power... its everything that comes off the DME for its power or signal to start. At first, I thought it was the DME Relay, but that was eliminated due to the power in Pin 26 or 27 (one goes through the relay, the other is a straight shot from fuse C1) of the DME connnector.

Well, that sucks. Any mods done to it? What about your alarm system? Any problems with that lately?

Edited December 23, 2005 by WARDHOG

[JebLacey]

Hey everyone...

I have been absent for a while. The box is in Tallahassee FL, Capital EuroCars. I spent about another 4 weeks troubleshooting, trying to confirm that I had the right idea, and all I have says yes... DME intermittant failure. Another key is that when I pull the DME off and shake it, there is something rattling inside. Is that normal (for you techs out there).

Anyhow, having the DME replaced. Had to call PNA to get that jumpstarted. I must admit, I like the people at Capital Eurocars. They have had their hands tied, since they ahve been unable to recreate the problem every time i take it to them. I understand that that isnt their fault, but I went to PNA anyhow with the info I had and I think it is going to get taken care of.

Just wanted to say hi and give an update...

BTW... drove a 996... thinking of crossing over. any advice? Money is an issue, as we are starting another business right now, and most of our financial effort will be going there, but I am smitten... I must admit.

Any MY or options to stay away from? Anything a must have?

Brian