stealths6

I have '01 Allroad which has been giving me fits. Trans is less than 2 years old, TC is about 3 yrs old. Tip has GIAC chip, and car has 125K miles. I was driving on interstate about 75mph, when the vehicle suddenly jerked/banged and quickly 'repelled' speed for just a second(can't adequately describe this except to say it is NOT a good sound/feel...pretty violent and sudden when it occurs) and sounded like the engine/trans was going to come out from under the car. But...I wondered if it was the brakes suddenly clamping hard for an instant. All the dash lights came and the car went into limp mode. (Stays in 4th and will clank up or down in gears to stay there--so I put in tip, in 4th only and was able to continue for a distance. I went to 5th and it drove fine for a while before it did it again. In normal mode, it is totally sporadic--sometimes will go for miles and nothing happens and others it goes into limp before end of drive. If hot, it stays in limp mode until it decides to become normal. The dash light showing indicators go blank when in limp. This has become intermittent, but check engine light has remained on with the ABS, and brake light coming on as well. Also when in full tilt, schitzophrenic mode the parking safety switch light near the shifter/and on console clicks like a geiger counter, (not quite) but is rapidly cycling, which leads me to believe is electronic. At speed I feel the car surging like the brakes are being applied on and off. I cleared the check engine light today and it has stayed off, however the car almost immediately went into limp mode once I started driving. Temp doesn't seem to play a role, however, I wonder if bumpy roads do...
Have talked to several Audi mechanics I know and they all say it's most likely the module, (normally is attached to side of pump and head and contains the electronics as well as the solonoids).


We ran VAGCOM scans and came up with several codes:
18034--Powertrain data bus missing--message from TCU
00302--ABS Solenoid Valve Relay, (J106)
01316--ABS Controller
01315--TCU no communication intermittent--this ties back to 18034 I think...
So...either the controller or the module is the culprit--but are they ONE unit or in two different places. Problem is for this year I have the Bosch 5.0 which has the ECBM allegedly in a different location than the pump/module location. Also found in the S-4, the 5.0 ECBM is located under rear seat. I looked in the Allroad and I don't see a computer...
At the head/pump, the black box attached to side has two wires coming from the bottom of the module and they go to the pump itself. The major connector lifts up and away laterally towards the fender but is vertical vs. horizontal in the other modules. 4 torx screws hold it to the side of the distribution head/pump assly.
Unlike the 5.3, the 5.0 isn't rebuildable per some of the sites I visited, because again, they say the module and controller are in two different places. My problem is I don't know where the ECBM is located. I've searched the net and nothing.
When I started to remove the module from the pump, I found the wires to be soldered and too short to snip and resolder without having to remove the head and pump. I had hoped I wouldn't have to crack the hydraulics on the car forcing a pressure bleeding.
Has anyone else been down this road and can you help? I only wish it was as reliable as my '95 S-6.

I've cleaned all connections, looked at TCU--it is dry and stable. Does anyone know if the 5.0 controller does in fact have the electronics in it, (vs. the S-4 which has it separate and under back seat?) Does anyone know what I should replace? A new unit, (again, I don't know if the ECBM would be considered part of this) is $992.00. I can probably scout up a used one for half that. I just dont want to replace the module when it could be the wrong piece.
I live in Chicago if anyone cars to weigh in. I really need help on this. Thanks.
Pat