Just two steps forward and one step backwards

As indicated in the prior post the next item of business is getting the speedometer hooked up to the vehicle speed sensor(VSS). I have two choices at hand for the VSS. I can use the OEM VSS that is part of the transmission. Or I can use the aftermarket VSS that came with the EVision.

Previously I had tried to use the OEM VSS. It's already mounted and ready to go. Unfortunately hooking it up to the speedometer gave no signal.

I had also tried the aftermarket VSS. The sensor is magnetic and generates an electrical signal when metal passes by (there are metal nuts under the black tape on the axle in the picture below).


This didn't work so I pulled the sensor and tested it using a drill with a couple metal nuts around the collar. This worked fine so I figured the sensor and nuts needed to be closer to each other. I went ahead and remounted the red sensor but couldn't find an acceptable position (either on the axle above or closer to the CV joint).

At this point I decided to go back to the OEM VSS. I had asked around on the Electric Vehicle Discussion List about the OEM VSS. Someone suggested that the newer VSS may need a pull up resistor in order to produce the necessary voltage for the speedometer.

So I went ahead and reconnected the OEM VSS with a resistor between the output wire and 12V power. Bingo! The speedometer started registering values.

Now to calibrate the speedometer. Luckily there are a couple of informational radar traps in the area. The speedometer requires a speed of 45mph to calibrate. So I buzzed by one of the radar signs and adjusted my speed till the sign said 45mph. Unfortunately it was a 25mph zone and I got a ticket....just kidding :-)

Once the sign said 45mph I pushed the calibration button on the speedometer. I now had a working and calibrated speedometer! Just to be sure I went by a couple more times at different speeds to check it.

Now the one step backwards part. In the process of fooling with the speed sensor I noticed a lot of grease on the chassis near the axle. This was definitely not there when I originally installed the VSS the prior week.

I tracked the source of the grease to one of the CV joints on the right front axle. Apparently there was a small hole in the boot protecting the joint. The grease was leaking out from the boot (actually flying out at 4000rpm). You can see the boot in the picture above (prior to it leaking).

Anyway I'll need to get a new boot to replace the damaged one. In the meantime to keep the EV on the road I have duct tape securing the hole and it seems to be working.