When testing the tranny fault code, let’s say for example we have a Ford Ranger with a tranny in limp mode and a P1747 fault code. In this example, we will use a 1996 model and reading the tranny wiring diagram, there are 3 main solenoids being powered by the pcm power relay. Checking these solenoids we have the torque converter, electronic pressure control and shift solenoids. With key on and engine off, all the voltage supply wires could be tested and verified.

During testing the tranny fault code, the engine pcm itself supplies the ground to tranny solenoids to make it work. A voltmeter continuity test can be made between these solenoids and the ecm power relay terminals including the pins to the pcm. Likewise, these tranny solenoids also can be powered individually by using jumper wires connected direct from the battery [each terminal for battery (+) and (-) post] and you can listen to the solenoids “clicking” if you can hear them work. These 2 simple tests should be enough to give you an idea if the solenoids are working or not. If we confirm that the solenoids are OK, we know the PCM is a suspect.

In testing the tranny fault code, the pcm can be tested quickly. Again using a simple digital voltmeter, you can measure the voltage of the pcm plug-in terminals. With key on engine off, you can test the voltage of the pcm ground and power supplies. If all voltage readings are zero and 12 volts respectively, we can conclude that the pcm is defective.

We can research the tranny common fixes for you if you need assistance. Make sure you provide the vehicle serial number so we can match the tranny for your specific vehicle. ATS takes this testing the tranny fault code further because while you are doing these tests above, our technicians are researching the common fixes from our database to see if there are any common design flaws on this vehicle. Example: some vehicles are prone to shorting of the solenoid wires ; some solenoids are also prone to fail themselves like the EPC solenoid for the above P1747 code. Do you think you can do these simple tests with ATS guidance? You bet you can!