ECM mismatch Diagnosis 2012 Toyota Hilux 2TR-FE - MechoMedics

Monday, 14 May 2018

ECM mismatch Diagnosis 2012 Toyota Hilux 2TR-FE


The Engine Control Module (ECM) of the Hilux is vital in the operation of not just the Engine System but I'll rather say the Powertrain System (Engine and Transmission System). This means that while some Vehicles have an Engine Control Module and another Control Module dedicated for Transmission control -Transmission Control Module (TCM), the 2012 Toyota Hilux uses just one and let's simple call this 'reference table and multi-system controller' the Powertrain Control Module  (PCM).
Without delay, I'll give you the History of the Vehicle fault. The Vehicle user had a flat Battery and wanted the Battery replaced and he mistakenly reversed the Terminal/Polarity while  putting the replacement Battery. Starting up the Truck with this setup instantly caused an electrical short circuit in the PCM hence the vehicle will not start. A Local Auto-Electrical expert was contacted to get a replacement PCM and he ordered a replacement PCM 89661- 21***(. The replacement PCM, which is a Freecode type i.e. does not need programming or coding, started the truck but the Transmission was slow in response and dragged in shifting; such that when you fully depress the accelerator down the maximum take off won't be obtained.
With the complex nature of the PCM and wiring to the Transmission and Engine System, you will like to have such a fault as this examined and Dignosed by those with the right tool and experience, and that is where MechoMedics comes in. 
After a Test Drive and fault confirmation, the first things you will want to be sure of in such a case as this is: Can I communicate with the PCM with my Diagnostic Tool?
This can be verified by hooking up a Diagnostic tool that can communicate with this Vehicle (With reference to Brand and Model) using the right cable connected to the 16 Pin Data Link Connector (DLC)  there was no communication. There is certainly a fault somewhere. The DLC connector supplied power and ground to the scan tool but communication using the different protocol was missing.
The next step was to verify the right PCM using the Chassis Number or Vehicle Identification Number (VIN) and this can be done using any of your workshop management softwares (AllData or Mitchell OnDemand) or if you don't have any of this simple check it out on the ToyotaDIY page.

The result help a lot in confirming why we had no communication, the PCM was a mismatch as the right one will be 89666-0K***.

With a good relationship with the local PCM retail vendor, a new PCM was supplied with the right Part number and even though it costed an extra cash, the job can be completed with this PCM.
When replacing PCM you will want to get the vehicle diagnosed ASAP, this is to ensure the following:
communication between PCM and Scan tool guaranteed, faulty sensor and actuator communication not caused by PCM, Vehicle Starts properly and no new DTCs registered after a Test Drive.

With the proper PCM, the Engine Started properly (No Hard Start, No Rough Idle, No Stalling), Transmission shifted with the expected speed changing from Gear 1 to 4 within less than a minute on a free way test drive, existing fault of Oxygen Sensors and Air-Fuel Ratio Sensor, knock Sensor and Secondary Air Injection Pump still existed.


N.B: The owner acknowledged the existing fault and didn't want them fixed at the moment.

That is what I call "Case Closed". Proper Diagnosis should be your first line of thought with your next Automobile Fault and I hope you find this information helpful. Thanks for reading and feel free to share!

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