Our latest featured service is ECU replacement on a 2006 Cadillac SRX.
2006 Cadillac SRX, rear wheel drive with 3.6 Liter engine
This Cadillac came to our shop with an interesting concern: sometimes when the ignition key was turned to start the engine would not crank over. From listening to our client's description of the problem it seemed like the vehicle might have a bad battery or starter motor. From trying to start the vehicle it became clear that something different was at fault. Another interesting issue was that the key would intermittently be impossible to remove from the ignition switch. It was apparent just by the erratic nature of the concerns that this was an electronic issue.
3.6 Liter engine with upper cover removed. Red arrow points to ECU
Our next step was to connect a scan tool to the vehicle, and from here we proceeded to do a scan of all vehicle modules. We found a couple of revealing trouble codes related to data link communication errors. Researching these codes further we found that 95% of the time the fault was with the ECU (Engine Control Unit).
Replacement of the ECU on this vehicle is fairly straightforward however it does require reprogramming. Modern car computers are all shipped without software programming because the ECU can fit a broad lineup of cars and all require different operating parameters. With reprogrammable software manufacturers can update the ECU, or any other module, as required. This happens from time to time as certain concerns become present. An example would be a check engine light that comes on due to the system being overly sensitive to certain sensor data. A reflash can eliminate this issue by reprogramming the computer with updated software.
Part of the ECU replacement is flash programming the new unit. Shown is our laptop and the J2534 interface.
One thing that I found very interesting about this job was how small the ECU was: it was about the size of a large smart phone, with two large electrical connectors. It used to be that most ECUs were an 8 by 8 wide, by 1 inch deep box but no more: micro electronics is very much alive in the automobile.
New ECU. Note the compact size
As for our Cadillac SRX, we installed the new ECU, performed the reprogramming and the vehicle ran great. Best of all it started every time we turned the key to start and the key came out of the ignition each and every time.
For more about the Cadillac SRX click here https://en.wikipedia.org/wiki/Cadillac_SRX You may find the transportation crash rating for this vehicle disturbing.
For more about ECUs click here https://en.wikipedia.org/wiki/Engine_control_unit
