The
Solution: Spring Loading the Actuator Mechanism
Introduction
Coastal Electronic Technologies makes a kit called "The Coastal Remote Trunk Opener" for the Toyota Prius. It's a wonderful modification that adds an electromechanical actuator to the trunk latch and a circuit that monitors the RF remote so that three clicks of the "unlock" button of the remote automatically triggers the trunk release. They shipped it promptly and the material was high quality. It had a great instructional video (as well as comprehensive instruction manual), and they even included a little box of Jelly Bellies (favored by none other than Dr. Who!).
After installing the kit and making all kinds of adjustments, the remote release worked great, but I found that I could only marginally get the original driver's-seat trunk-release lever to work. Because of the retraction of the Coastal actuator, and friction inside the latch mechanism, the latch would often spontaneously go into "valet" mode and refuse to work via the front-seat lever. Now I know I could use the electric button at the driver's seat and tap-tap---tap to release the trunk, but I was interested in full functionality if possible.
The Mechanism
I removed the trunk latch assembly and looked at the mechanism. (I wish I had taken a picture...) The trunk is released when the release linkage rod (from the key lock to the latch mechanism) is forced down by the key turning right. If you pull the rod up past normal mode (which the key does in valet position all the way to the left), it moves a rotating plate (in the latch mechanism) off center of its operating center (it has an oval hole for this purpose). In this position, a tooth on the remote-cable rotating plate misses the mating flange in the now-off-center release plate and will not release. When the key is turned from valet to normal mode, the linkage rod moves the release plate back down to its normal rotating position, where the remote-cable plate can catch it and force it to release. Sorry if this is a bit obtuse, but the main idea is that if the linkage rod is not fully down, the latch behaves like it's in valet position and the remote-cable (from the driver's seat lever) will not release.
The Requirements
I needed a way to accomplish these three things:
The
Solution:
Spring Loading the Actuator Mechanism
The picture to the right shows my modified actuator mechanism.
Click here or on
the image for a high-res view.
These are the modifications I made:
The idea here is to allow the actuator to do its thing by compressing the spring and forcing the lock-latch linkage rod down to release the latch. The travel of the actuator is easily sufficient to accomplish this with the springs.
Also, when the actuator retracts, the springs maintain downward force on the lock-latch linkage rod and prevent it from withdrawing any more than the internal return springs of the latch mechanism want it to. This way, it keeps the latch mechanism plates from spontaneously going into valet mode.
Spring/Clamp Detail
Here is a detailed image showing the clamp and the spring. The key has been turned all the way to the left to valet mode to bring the clamp into view, and the actuator has been unscrewed and moved back ato avoid compressing the springs.
Notice the setscrew on the Coastal actuator's rod has been removed. This allows the acutator to move freely through the hole in the clamp to compress and free the springs.
I didn't do this but some grease on the Coastal actuator rod would help the operation by resisting binding as it moved through the clamp.
I could only get 0.5" spacers and 1" springs (I cut one spring in half to make 1.5" of spring) but you would do well to get a solid 1" spacer and 1.5" spring.
Valet Mode
This is the crowning glory of my modification. The key can be turned all the way to the left and removed for full valet mode. The leftward movement of the key (and concommitant upward movement of the key-latch rod) simply compresses the springs. It increases the resistance on the key, so to remove it in valet position, you have to maintain rotational force on the key while you pull it out. This might be made easier by using 0.5" of spacers and 2" of spring rather than 1" spacers and 1.5" spring like I did it.
When you click three times on the remote and the Coastal actuator tries to force the release, it doesn't force very hard. When it meets resistance, it gives up right away. Seems to be some current-limiting force-feedback in it or something, or maybe the actuator just makes the attempt for a short enough period. I don't think it's doing any harm.
Split-Loom
Tubing for Cable Conduits
Just FYI: I dressed all my cables (except the sensor cables GRN and BLU that run under the scuff panel to the driver's seat) in corrugated split-loom tubing. This should protect them from chafing on edges like the metal openings in the trunk that they go through or lay against. With enough vibration over time, especially with seasonal extremes of temperature, the insulation can fray and crack and expose the wire inside which can short against body metal.
You can see how the matching split-loom cable creates a more professional appearance than undressed wires alongside the stock conduit. By tracing the path of the stock conduit, I also insure that the flexing is at an optimal position (assuming Toyota paid attention to this, which I would think they do) and definitely keeps it safe and out of the way.