Hey all, I installed the Mazda tow hitch and tow harness on my CX-90 PHEV Premium this weekend. I did not plan on writing a how-to but after a few issues with the provided instructions, I’m hoping a couple of comments and pictures will help others that choose to install their own hitch. Apologies for the poor pictures, this post was an afterthought.
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When I bought my CX-90 back in May it was the first PHEV through my dealer it did not come from the factory with the tow hitch and the dealer didn’t know when the hitch would be available for purchase. This weekend I picked up the hitch and harness from the dealer for $660+tax. I did not ask the dealer about their install price because my plan all along was to install it myself.
I’ve installed tow hitches and electronics on 3 other vehicles, so I thought I knew what to expect. I’d consider the CX-90 on the more challenging side for two reasons:
No where did the instructions say to lift the vehicle, but a lift or ramp may be helpful. My driveway has a slight dip at the end to the street gutter and parking the front wheels in the dip gave me good enough clearance in the rear to not need any added lift.
I set the parking brake. I also chocked the tires, safety first.
Next I opened the rear lift gate, unlocked all the doors, rolled the driver’s window down, and popped the hood.
Instructions say to remove the negative battery connection per the workshop manual. (If anyone has access to this or knows how to order one, let me know).
The 12v battery is kind of hidden on the passenger side under a giant positive terminal distribution block. There is just enough access to get a 10mm socket on an extension back to the negative terminal. I then wedged a non-conductive panel removal tool between the battery post and the negative wires. This all stayed in place until I reconnected the battery.
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Mechanical Assembly of the Tow Hitch
Removing the bumper support in Step 2 was the first terrible modern clip I was challenged with. Even with a pick tool, the clips are annoying to pop out without breaking. I’ve broke this style clips on other vehicles and did not want to break these, so it took me way too long. My patience was tested but they finally came out without damage.
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To get the driver’s side tow plate into position, the bracket you will loosen in Step 5 holds up part of the EVAP and emissions control system. It seemed to have plenty of flex, but be careful to not knock anything loose.
I checked the M14 bolts fit into the frame where I had removed the tape covers. Everything was smooth and easy. And led me to my mistake of overconfidence with the M12 bolts.
I bolted up both side plates loosely as instructed. Which still wasn’t loose enough. I ended up unbolting the rear passenger side bolt and quickly reassembling it when the main hitch assembly didn’t want to slide into the correct position. Having two people to hold the main hitch assembly while positioning it under and behind the bumper is key. Step 10 in the instructions say required for good reason.
One sensor connector does get in the way of the main hitch install. I traced the wires and it seems to be for the foot sensors of opening the rear hatch. The connector and wire are right in the way when moving the main hitch into position. The wires in question are interestingly shown in Step 14 of the instructions. I disconnected these wires moved them out of the way and then put them back together after the main hitch bar was secure.
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The next delay in assembly I had was with the M12 bolts connecting the main hitch to the side plates in Step 11. These I did not pre-install or check the threads were clear. Unfortunately, there was a bunch of overspray gumming up the threads and it took me an extra long time to get each bolt to grab the threads in the welded on nut of the side plates. I should have take the main hitch assembly back off and run the bolts into the nuts. But I was stubborn and kept the main hitch balanced while I fought the bolts through the extra paint. I checked, nothing was cross-threaded and the overspray was pushed aside so I don’t believe the set torque was affected in any way.
Torquing the bolts was as simple as following the instructions.
I used an oscillating tool to cut the bumper support then I sanded the cuts to make them look almost factory perfect. It’s a totally hidden piece of plastic, so almost still looks good.
And that’s the mechanical hitch installed. On to the wire harness.
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Electrical Assembly of the Wire Harness
Even after reading the instructions, I expected the harness to be positioned somewhere in the middle of the driver’s side rear panels closer to the c-pillar than the d-pillar. But no, this whole panel removal exercise is to locate the wire harness below the driver’s side taillight under the d-pillar, just out of reach of the spare tire compartment.
This is definitely my biggest complaint with this install. Instead of the engineer’s figuring out how to install the trailer ECU and wiring in or on the edge of the spare tire compartment, it’s just out of reach deeper in the side well behind plastic paneling that has no business needing to come off. A little more foresight and electrical plug relocation and the wire harness install could have been a 5-10 minute job. Instead it was like 90+ minutes of frustration and stress to not scratch up or break my interior panels.
The whole effort of disassembly of the interior panels is well documented by Mazda and describes taking it all apart quite well in the instructions
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. I’m not going through each step. But I will say go slow, use panel removal tools, and find where to pull on the panels. Don’t just tear the panels off and break a bunch of clips.
The main side trim panel flexes a lot and needs to be wedged out from under the 3rd row seats.
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After getting everything apart per the instructions, the wire harness took me maybe 5 minutes to attach. That’s including the wait time for cleaning the area for the cable tie mounts. PS Mazda, please include alcohol wipes in the kit, I had to find my own.
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And once the wire harness is installed, Mazda’s tech writers give up on us by saying “reinstall parts in the reverse order of the installation procedure”.
So the main side trim panel that was tough to get out is basically impossible to put back by reversing the procedure.
What is great is that there is a built in solution. The main trim panel has a sub panel that comes off right where the suspension is located. I’m sure this is great for replacing shocks/struts, but in our case it means the main trim panel can be reassembled. After struggling for a long time to wedge the main trim panel back under the 3rd row seat bottom that is hidden under the folded down 3rd row seat back, I realized the sub panel comes off.
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So here’s the solution that worked for me:
I added the fuses where instructed (a detailed fuse diagram would be great Mazda).
I reattached the battery, checked the trailer wiring, and was good to go.
The instructions warn you to expect all your presets, radio, seat memory, etc to be cleared back to factory default. Mine were not. The car remembered everything. Not sure if that’s because I didn’t do something correctly disconnecting the battery terminal, or it’s the PHEV, or the instructions are just overly cautious. Any way, it saved me the time and effort of those feature set ups again.
The dashboard now shows a greyed out “Tow Mode” in the Mi-drive options that is selectable when a trailer plug is inserted.
Job well done. Check your lights, check your brakes, check your safety chains, and happy towing!
![Image]()
When I bought my CX-90 back in May it was the first PHEV through my dealer it did not come from the factory with the tow hitch and the dealer didn’t know when the hitch would be available for purchase. This weekend I picked up the hitch and harness from the dealer for $660+tax. I did not ask the dealer about their install price because my plan all along was to install it myself.
I’ve installed tow hitches and electronics on 3 other vehicles, so I thought I knew what to expect. I’d consider the CX-90 on the more challenging side for two reasons:
- The hitch bar weight and position on the vehicle means two people are necessary to assemble it correctly without damaging your beautiful ride. It tucks behind the bumper which looks nice but is harder to position.
- Disassembling 25% of the rear interior panels just to get to the driver’s side far rear corner is an effort in patience. This seems like poor design or at least an engineering afterthought, more comments below.
No where did the instructions say to lift the vehicle, but a lift or ramp may be helpful. My driveway has a slight dip at the end to the street gutter and parking the front wheels in the dip gave me good enough clearance in the rear to not need any added lift.
I set the parking brake. I also chocked the tires, safety first.
Next I opened the rear lift gate, unlocked all the doors, rolled the driver’s window down, and popped the hood.
Instructions say to remove the negative battery connection per the workshop manual. (If anyone has access to this or knows how to order one, let me know).
The 12v battery is kind of hidden on the passenger side under a giant positive terminal distribution block. There is just enough access to get a 10mm socket on an extension back to the negative terminal. I then wedged a non-conductive panel removal tool between the battery post and the negative wires. This all stayed in place until I reconnected the battery.
Mechanical Assembly of the Tow Hitch
Removing the bumper support in Step 2 was the first terrible modern clip I was challenged with. Even with a pick tool, the clips are annoying to pop out without breaking. I’ve broke this style clips on other vehicles and did not want to break these, so it took me way too long. My patience was tested but they finally came out without damage.
To get the driver’s side tow plate into position, the bracket you will loosen in Step 5 holds up part of the EVAP and emissions control system. It seemed to have plenty of flex, but be careful to not knock anything loose.
I checked the M14 bolts fit into the frame where I had removed the tape covers. Everything was smooth and easy. And led me to my mistake of overconfidence with the M12 bolts.
I bolted up both side plates loosely as instructed. Which still wasn’t loose enough. I ended up unbolting the rear passenger side bolt and quickly reassembling it when the main hitch assembly didn’t want to slide into the correct position. Having two people to hold the main hitch assembly while positioning it under and behind the bumper is key. Step 10 in the instructions say required for good reason.
One sensor connector does get in the way of the main hitch install. I traced the wires and it seems to be for the foot sensors of opening the rear hatch. The connector and wire are right in the way when moving the main hitch into position. The wires in question are interestingly shown in Step 14 of the instructions. I disconnected these wires moved them out of the way and then put them back together after the main hitch bar was secure.
The next delay in assembly I had was with the M12 bolts connecting the main hitch to the side plates in Step 11. These I did not pre-install or check the threads were clear. Unfortunately, there was a bunch of overspray gumming up the threads and it took me an extra long time to get each bolt to grab the threads in the welded on nut of the side plates. I should have take the main hitch assembly back off and run the bolts into the nuts. But I was stubborn and kept the main hitch balanced while I fought the bolts through the extra paint. I checked, nothing was cross-threaded and the overspray was pushed aside so I don’t believe the set torque was affected in any way.
Torquing the bolts was as simple as following the instructions.
I used an oscillating tool to cut the bumper support then I sanded the cuts to make them look almost factory perfect. It’s a totally hidden piece of plastic, so almost still looks good.
And that’s the mechanical hitch installed. On to the wire harness.
Electrical Assembly of the Wire Harness
Even after reading the instructions, I expected the harness to be positioned somewhere in the middle of the driver’s side rear panels closer to the c-pillar than the d-pillar. But no, this whole panel removal exercise is to locate the wire harness below the driver’s side taillight under the d-pillar, just out of reach of the spare tire compartment.
This is definitely my biggest complaint with this install. Instead of the engineer’s figuring out how to install the trailer ECU and wiring in or on the edge of the spare tire compartment, it’s just out of reach deeper in the side well behind plastic paneling that has no business needing to come off. A little more foresight and electrical plug relocation and the wire harness install could have been a 5-10 minute job. Instead it was like 90+ minutes of frustration and stress to not scratch up or break my interior panels.
The whole effort of disassembly of the interior panels is well documented by Mazda and describes taking it all apart quite well in the instructions
The main side trim panel flexes a lot and needs to be wedged out from under the 3rd row seats.
After getting everything apart per the instructions, the wire harness took me maybe 5 minutes to attach. That’s including the wait time for cleaning the area for the cable tie mounts. PS Mazda, please include alcohol wipes in the kit, I had to find my own.
And once the wire harness is installed, Mazda’s tech writers give up on us by saying “reinstall parts in the reverse order of the installation procedure”.
So the main side trim panel that was tough to get out is basically impossible to put back by reversing the procedure.
What is great is that there is a built in solution. The main trim panel has a sub panel that comes off right where the suspension is located. I’m sure this is great for replacing shocks/struts, but in our case it means the main trim panel can be reassembled. After struggling for a long time to wedge the main trim panel back under the 3rd row seat bottom that is hidden under the folded down 3rd row seat back, I realized the sub panel comes off.
So here’s the solution that worked for me:
- Remove sub panel from the main trim panel.
- Carefully wedge and flex the main trim panel back in place under the 3rd row seat bottom while making sure the plastic clips all orient themselves correctly not to break or fall off
- Once the main trim panel is back in place, add the sub panel back over the suspension area by carefully wedging it under the 3rd row seat bottom and clipping it to the main trim panel.
I added the fuses where instructed (a detailed fuse diagram would be great Mazda).
I reattached the battery, checked the trailer wiring, and was good to go.
The instructions warn you to expect all your presets, radio, seat memory, etc to be cleared back to factory default. Mine were not. The car remembered everything. Not sure if that’s because I didn’t do something correctly disconnecting the battery terminal, or it’s the PHEV, or the instructions are just overly cautious. Any way, it saved me the time and effort of those feature set ups again.
The dashboard now shows a greyed out “Tow Mode” in the Mi-drive options that is selectable when a trailer plug is inserted.
Job well done. Check your lights, check your brakes, check your safety chains, and happy towing!
. My question was regarding 
