To answer some questions raised in this thread:
1. The BRM (or at least mine) will definitely run without the G28 signal. Apparently, as it uses the cam speed sensor as reference in the absence of the G28 crank sensor. Without the G28 sensor connected (or with a faulty signal) the start is much, much slower with an extended cranking time.
2. The Ground Points list posted in page #1 is as listed in Bentley’s. My car does not have a ground wire at every attachment point. Many ground points had multiple grounds connected thereto. Other, albeit, unused ground studs exist on the A5 platform as I found numerous such points when checking the Bentley’s listed points. The problems my car experienced were a result of harness chafe not ground point/corrosion related.
3. There was a disparity in the fuse numbering and purpose between what actually exists in my car and those shown in my owner’s manual and in Bentley’s. Bentley’s and the owner’s manual did not agree either. The owner of a similar production period A5 informed me of the same thing. I encourage every A5 owner to photograph their fuse blocks for recordation purposes.
4. I had multiple chafe points in my harness. The one at the starter solenoid was the first I happened into. Other chafe existed further up the harness.
5. The BRM harness layout is such that the heavier gage conductors are in the center, or core, of the harness. The lesser gage (sensor signal and twisted pairs) are around the circumference the harness core. The harness root and size is such that it is not very flexible. The stresses, movement & weight are point loaded at the supports, ECU, and the junction near the left head (opposite side from the timing belt). The plastic of the split looms is harder then the conductor insulation. Therefore, when chafe occurs, the very small gage, .35 mm (or about 26 to 28 ga.) signal conductor’s insulation is sacrificed to the split loom and harness movement is carried by the smallest wires with the least insulation.
6. I have learned of other BEW & BRM engines which have experienced similar problems. I have not established if the 2.0T &/or the 2.5 gassers have similar problems. Some have filed a complaint with the NTSB as have I.
7. I filed a warranty claim with VW; which VW promptly denied. If others are filing a similar complaint, please feel free to PM me as I will be more than happy to provide you with my file number so that you may establish a pattern. I am appealing the warranty denial (As others have said, VW’s warranty is not good for much).
8. Oilhammer's comment that the 2g28 sensor rarely goes bad is spot on. It is a bugger to access and R&R on the BEW & BRM's. If you are suspecting a problem there, you may save o lot of time by checking your harness first.
Much thanks to assistance and direction in repairing this problem to: Dan, Rich, Joe, Brian, Oliver, Jeff R., Ross-Tech, Impex and especially to Fred for this site which made this (and other past ones) repair so much easier to diagnosis & repair. A donation was made as way of thanks.
While I cannot verify it, my suspicion is that this condition had been developing for quite a while, perhaps back to about 20K. miles or so. Very occasionally, the car would very rough, almost as if it were out of time. As the condition could not be replicated and occurred occasionally, I figured it was just one of those things. The discoloration in the chafed copper conductors indicated that the condition had been developing for a long period of time. If you have concerns, your may want to voice it to VW. See Brian’s post re. the NTSB. I hope of other's sake that mine, Brian's & the others I happened into are isolated failures. But, BEW & BRM owners: Heads Up.
as it was showing errors into window and other components. After I opened the split loom ID'd & function checked the conductor color coding I understood when I learned that one of my damaged wires was related to the engine and instrument cluster diagnostic circuit.
