I got a call from “old dog” Marky one day with a bit of a curly problem. Luckily it wasn’t a crazy ex-girlfriend but rather a VZ Commodore with a 175kw Alloytec and manual gearbox that was throwing code U2106 and “See Dealer” message on the dash accompanied by the classic dash beeping. If you’ve every worked on a VT onwards that had some sort of error code and the dash starts beeping you’ll know what I mean, it’s the sort of sound that’s enough to set off shell shock in the weary car technician.

What was interesting in this case is that the car had been pieced together from parts, (or so we were told), had a manual gearbox which matched the build plate – MV5 6spd Asin Gearbox. First port of call was to scan the car with the workshops Snap-On Modis Scan Tool. A few codes came up which were unrelated to the current problem and of course the U2106 lost communication with transmission control. Given it is a “Uxxxx” code, we know it wasn’t set by the ECU (or potentially any of the drivetrain control modules).

First step was to scan the PIM specifically to see if it came from that module. PIM stands for “Powertrain Interface Module”, this module is used in the VZ V6 Commodores as an interpreter between the CAN bus modules, (typically ECM, TCM & ABS) and the ALDL devices mainly BCM. See the below diagram courtesy of Snap-On

Once it was confirmed it was the PIM issuing the error code, we checked the Configuration of the PIM using the “PIM Configuration” option in the Snap-on Modus menu.

Sure enough, we found the smoking gun! The PIM was out of an Automatic car and was still configured to look for a 4L60E Automatic. It looks like a PIM from another car was used and then relinked with the BCM and ECU so security would pass and the car would start however the rest of the steps weren’t done to configure the options in the PIM to suit the current car…

Using the Modis, we went though the options and configured all the subsystems to suit the car: Transmission etc. and all was well! Thankfully we had a good scan tool at our disposal – N.B. you could of course use a TECHII to do the same thing but we didn’t have it handy.

So, if you’re getting a mystery U2106 code – check your PIM configuration!