Audi and VW Transmission Electrical Problems
Audi and VW automatic transmissions are quite prone to failure. The most common Audis are the A4 and A6, which, along with the VW Passat, share the ZF5HP-19 5 speed automatic transmission, produced by ZF of Germany. The VW Jetta, GTI, and Golf with 4 speed automatics utilize the 01M transmission, made by Volkswagen, while the 5 speed models come with the JF506E transmission, made by Jatco, a spin off of Nissan.
Each of these transmissions in use has unique problems, which can often be elusive. At Suburban, we have made large investments into the most advanced tools for diagnosing transmission and electrical problems, which, when coupled with years of experience, assures an accurate diagnosis.
An incorrect transmission repair diagnosis could cost a customer thousands of dollars. A recent example is a Passat that came in with transmission codes and obvious shifting problems. The customer had already been told by the VW dealer that the transmission required replacement. A first glance, this seemed like a transmission problem, but, we had never experienced these specific symptoms on any other Passat (or the Audis that share this transmission). Using specialized equipment allowed us to see that the shifting problems were actually being commanded by the vehicle’s computer. The transmission was doing what it was being told to do. This information led us to look elsewhere, and the cause of the problems turned out to be a defective Mass Airflow Sensor (MAS) on the engine. This was obviously much less expensive than replacing the entire transmission. As a result, the expertise of our technicians saved this customer great expense.
Audi A4 Transmission Service Codes
Automatic transmission service codes can appear when scanning an Audi A4 that is suspected of having transmission problems. While code P1793 and P0706 are both transmission related, they would usually be considered unrelated to each other. A bad speed sensor would never cause the inhibitor switch to malfunction, or produce a P0706 code. A slipping or broken internal component could produce an Audi A4 output speed sensor code P1793, though never an inhibitor switch P0706. The brake boost vacuum system code is unrelated to transmission, and may have existed before.
Audi Transmission Electrical Problems
The 2 transmission codes are related in that they are both electrical signal codes. Unlike performance codes, which are tests that were completed but failed, signal codes usually lead to open or shorted wiring circuits. These Audi A4 tests show an electrical malfunction, not a transmission malfunction. Electrical circuit codes and their related problems should be corrected before attempting to properly diagnose the transmission itself. This doesn't mean that the Audi A4 transmission is not also malfunctioning, or that the electrical circuit problem is not occuring inside the transmission, but only that the issues should usually be treated as separate concerns. The most likely cause of the Audi A4 transmission codes is an external wiring problem, not an internal transmission problem. I have corrected many problems by cleaning wiring harness connections with brake cleaner and replacing terminal connectors that are heavily corroded. Any repairs that were recently performed, especially if they are related to engine or transmission wiring, should be inspected.