Review of Coastal EV switch experience

This is a review of the Coastal Tech EV switch installation experience.

I'll start off by stating that I've never ever taken apart a dash board before, so doing this installation was pretty scary to consider. However you'll find that the dash board disassembly is minor and surprisingly easy. It is the removal of a plug and insertion of a pin that prove to be the most unnerving. The instructions recommend that you get a professional to install this, but to be honest I don't know where you are going to find someone that will install this for you unless you sign some waiver saying you won't hold them liable for a bad installation. It's easy to do a bad installation. And by bad installation, I don't mean damage the car, but more likely they'll install it and the EV switch won't work and the installer won't know what you are talking about.

For starters I did want to say that the ordering experience was fast. I ordered it one day and that same day I got a UPS tracking number by email. Within a few days I received the unit. It's a small part about the size of a stamp with 3 wires sticking out. Two of them have spades meant to be hooked up to wire taps, and a third has a pin. It's that third wire with a crimped pin that is the most difficult part of the installation. Coastal also packages a total of 4 wire taps and an extra spade. Only 2 wire taps are needed. A 3rd wire tap and the extra spade are tapped into a demo piece of wire so you can see what a correct wire tap looks like and how much force you'll need to apply to get a wire tap snapped into place. The extra piece is hooked onto this demo wire tap so you can see what a properly seated spade looks like. Then there is yet one more 4th extra wire tap that is just there as a spare, in case you loose or break one of the wire taps. Actually it turns out that this 4th extra wire tap comes in very handy to do electrical diagnoses of the installation.

In my first attempt to install this, I was a bit nervous and cold outside. I have no garage so I was doing this in a parking lot and was being pressured by cold winds and an oncoming weather. The instructions on taking apart the dash components were excellent and the parts came off really easy. I would have added one more step of taking out the glove compartment damper unit completely for more clearance (an extra 10 seconds of effort). Next you have to pull out one multi-pin connector. This part proved tough because unlike the picture shows you don't have enough of the dash removed to get a direct path to this connector. I had to take off my winter coat because my forearm couldn't reach down far enough to reach this connector. With one hand you have to hold this snap release down. With the other grab a hold of some of the wires and gradually wiggle this connector off. It takes a lot of force to remove this connector, but you want to take your time as you don't want to damage the wires. Just be aware that when you are tugging on this connector it may seem like you aren't making any progress, but you are. It's just that with each tug you get it to move fractions of a millimeter. Once you get about 3 mm out, it will just come out completely.

Next, I carefully followed the instructions to correctly wire tap two wires. This part took me some time because YOU DON'T WANT TO WIRE TAP THE WRONG wires. So I looked over the instructions over and over. I looked at the connector diagram. I counted towards the correct wire on the connector. I verified the colors of the wires. I checked and double checked. Then when I was absolutely sure put on the wire taps. The wire taps are not exactly easy to put on because you need to use your fingers to fit it in place, but your fingers won't be strong enough to squeeze down. So you need to get pliers in there. It's a little tricky because the space is really tight and if you don't do it right by the time you get the pliers in place the wire tap will have slipped off and you have to do it all over again. The instructions mention to avoid trying to re-tap a bad wire tap attempt. I was in no mood to putting in wire tap marks all over the same piece of wire as I feared that too much of that kind of stress might break the wire. If you ever cut one of these wires it would be an absolute nightmare trying to re-attach them. Anyway, I got both wire taps on successfully.

Then you get to the pin insertion. The instructions make it pretty clear that this is one area where it's easy to think you're successful when you are not. You need to lift up this latch and then insert this pin and then use a jewelers screw driver to push it in a bit further. I got the latch up without a problem. I inserted the pin and then pushed down hard as I could and assumed that it had to be in because I used a lot of force. I then tried to close the latch but I couldn't remember what the closed position looked like. I then plugged the connector back in and put the dash board parts back on. Then I turned on my Prius and tried to turn on the EV switch. Nothing! The gas engine then turned on and my Prius was idling just as normal. Then after a few minutes the car was warmed up and the gas engine stopped. This was a failed installation attempt. Total time: 1.5 hours.

I then read a description of the EV switch installation put out by Evan Fusco. This one describes how to do a true EV switch and install it in the same spot Toyota would have installed it, if it was available in the US. Evan Fusco's installation procedure is more difficult but has a nice picture of what exactly is going on with this tricky pin 27. The next weekend I tried again, but now armed with a digital multi-meter to test for good electrical connections. This 2nd installation attempt, I tried to be extra careful in removing the connector because there was a good chance my first installation did not secure the connector latch. If true this might mean if I tried to tug on the wires, the wires might pop out with the connector still plugged in. If this happened, it would not be good. So with painstaking effort, using my finger tips, finger nails, and part of a screwdriver that happened to be just the right length, I got the plug off without tugging on the wires. I then disconnected the EV module and started touching the multimeter to the wire taps and the corresponding connector pin. All the wire taps beeped on the multi-meter so I knew the wire taps were good. I then took the extra wire tap and wire tapped the 3rd wire of the EV module that has the pin. The pin was slightly bent so I straightened it out. Then I inserted it into the pin 27 hole of the connector and this time used a jewelers screw driver to push it in. This time it went in further than before. Then I put the multimeter to this wire tap on this 3rd wire and the connector. It beeped! So now I knew that this installation had to work. For anyone considering doing this EV switch installation using a multimeter is definitely worth it, because otherwise it's a lot of trial and error with turning on the Prius and seeing if it works and if not pulling this connector out. Remember it's hard to pull this connector out.

After about another 1.5 hours, this time I was successful! I started my Prius. Then immediately pulled the cruise control cancel stalk in and after about 2 seconds I heard a single beep. I waited 10 seconds and my Prius stayed silent, no gas engine start. Then I backed out and started driving around the parking lot, with no gas engine. To cancel the EV mode you just hold the cruise cancel again for about 2 to 3 seconds. Sometimes you'll hear a triple beep when the EV mode is canceled. However, sometimes you'll hear nothing. So with this EV switch you kind of have to mentally figure out if you've turned on EV or not. There are no visual indicators of whether or not you are in EV mode as far as I can tell, except by how the car is behaving.

Last night I drove about 300 yards out of my parking lot in EV mode with almost a full battery. Then the moment I was about to merge into traffic, I turned it off and started to accelerate briskly. I heard a triple beep but noticed that the battery was getting heavily drained. I proceeded up a steep hill on which I normally get about 20 mpg and saw about 45 mpg, and I was accelerating pretty well! I watched my battery drain down quickly to two bars within a matter of seconds! It was a bit alarming as it seemed I was still stuck in EV mode. However, after another minute of driving it was becoming clear that I really was out of EV mode. It's just that since my gas engine was cold, the Prius had no choice but to put the brunt of effort on the electric motor.

So now I can sort of understand why they may have left the EV switch off for the Prius. If for example you drove on pure electric to the edge of merging into fast moving traffic on the highway, what could happen is that the moment you accelerate hard the Prius gas engine will just have started and won't be ready to give you much power. When that happens your electric motor will be going full power and will give you a momentary illusion of good acceleration. However, if your battery can't hold out for the duration of the acceleration, what could happen is that the electric motor cuts out and you're stuck with just a the gas engine that still hasn't fully warmed up an so you experience a drop in power and so get caught off guard while merging into fast moving traffic. So if you're an aggressive driver having the EV switch on when your gas engine has never warmed up could be hazardous. However, if you plan on driving moderately with this EV switch, you should be OK because you won't attempt to make a merge where you have to accelerate hard. If you do install the EV switch on your Prius, I would limit it's use to initial movement out of the parking lot and the end of a drive when looking for a parking place. When you know for sure you're going to be merging into traffic that is above the 25 mph speed limit it's time to turn this EV switch off and let your gas engine come alive.

If you limit the use of the EV switch to only slow parking lot situations you will notice an improvement in your gas mileage. If you elect to install a true physical EV switch like the one Evan Fusco describes, you'll have the advantage of a visual indicator of whether the switch is on or off. However, the physical switch installation is much harder to do. If you do the Coastal EV switch module, you'll lose the visual indicator, but it's a much easier installation. Another big plus is that the switch resets itself when you turn off your car. This means if I leave the EV mode on while I drive, and then my wife then drives the car and the EV mode be off. So there's peace of mind that I don't have to teach her about the EV mode and I don't have to remember to turn off the EV mode before leaving the car. It's invisible to inexperienced Prius drivers. So now what I do to turn on and off the EV mode is get into the habit of just counting mentally in my head. If I pull the cruise cancel and hold and count to 4 seconds then I know I've toggled the state of EV mode.

One other thing about the EV mode. Supposedly when you trigger the EV mode you're AC can't be working. As far as I can tell I was able to keep the heater on when I turned on the EV mode and the heater continued to output heat. However, there was also a time when I turned off the EV mode with the heater on and heard no beeps until the very moment I turned off the heater, and then I heard 3 beeps. So it's a bit unclear in my mind what the relationship is between the A/C being on and the operation of EV mode. It's also not quite clear under what conditions you'll get beeps.