Aftermarket October 2022

OCTOBER 2022 AFTERMARKET 29 was fault, but how do we prove it, as well as the ECU-to- connector integrity? What I did at this point was to ground the signal down, pulling it to ground and reread the DTC. As expected, we now had two DTCs for the LIN bus, two malfunctions, but two different DTC codes. This proved wiring and response integrity of the circuit, so I deduced that a new alternator was required. What arrived was an aftermarket example, due to availability problems with the OEM part. With the new one fitted by my colleague, which is not the easiest to do, the shout came out “Kev it’s still the same - not working!” As always, you get that sinking feeling and question yourself. What did I miss? Back to the job then. Rescanning the original DTC returned ‘U1132 lost communication with Generator –Active’. Believing it was the alternator at fault, I ran through the tests again just in case I had missed something, but the results were conclusive; Definitely the new alternator at fault. So, another one was ordered, this time from a different manufacturer. The part duly arrived, only this time I wanted to try before we fitted it to the vehicle. With the second new one in front of me, I extended the LIN bus communication line to it outside the vehicle. I thought, I know, I will put the jump box on to the alternator to give it live and ground, this should allow it to talk. By now, some of you will be ahead of me doing the test this way. Without the B+ and the vehicle ground connected to the alternator, how can the circuit be complete for feedback logic to work? When the CTC was checked to see if it cleared, it did not. Steady charging voltage We extended the B+ wire and a ground connection along with the LIN bus wire to the second new alternator on the tool box. The DTC was checked again and erased and did not return. Next, I cycled the ignition a couple of times to make sure it didn’t return and rechecked; No DTC returned for loss of comms with the alternator. With this product seeming to be okay, it was installed and tested. Charging was occurring and control of the alternator was taking place. With the scope recoupled to the Lin bus signal and the headlamps turned on and off we could plainly see the LIN bus control signal altering on the scope screen. We could also see the charging voltage staying steady, at around 14.2 volts, thereby proving the repair. Please refer to Fig.2 With this saved to the scope for future reference we could now hand the vehicle back to the customer with confidence in our repair. A full post repair global scan was also taken once we finished the job. This allowed us to be aware of DTCs in other system which bear no relationship to the repair we carried out. This enabled us to advise the customer of up-and-coming likely future repairs, should they wish to do anything about them. Below: Fig 2 Above: Fig 1