Mazda TCM Troubleshooting

I see what you're saying. On your vehicle, the Grounds are "L" and "M" - right between the yellow power cables. Those are your ground wires. 

Hello everyone. Thank you in advanced. Trying to trouble shoot my TCM after I got it back from UPFIX. I'm getting no communication with TCM. I'm NOT getting continuity from positive post of battery and wiring harness of TCM.I have continuity between ground and harness. Fuse is ok. Before I sent the TCM for repair the tranny was working perfect, but it will go on the limp mode on and off . All this is new after i got my TCM back. Anu suggestions will be highly appreciated.

Hi there, please check the wiring first and foremost. Back-probe with a multi-meter into the back of the TCM. Check to see if you're getting ohm resistance between the Can-Hi & Can-Lo pins. If there is resistance, that's good. Next, back-probe the power pins with 'ignition on' on the connector and check for continuity between the battery and the two power pins.

If there is no continuity, it's not the TCM but something preventing the TCM from being powered on. Check for any bent pins, corrosion, and any power relays/fuses for the TCM. It's good that you confirmed there is ground reaching the TCM; however, if there is no power from the 12V battery to the pins on the connector for power, something along the way is down.