The Fix is in.

"The electric motor itself needs no lubrication. However, the brushes should be checked every 6 months or 3,000 miles for tightness and proper length..."
- Comuta Car service manual


The weather is cold now. We've had a few snows. It's cold enough to reduce battery capacity to a level that prevents me from reaching the Metro station and coming back without charging up. It's not a great time to lie on the ground doing mechanical work.

Still, curiosity will drive me outside every time. I want to know what's wrong with the Comuta Van and how expensive it'll be. I suspect the potbox that attaches to the accelerator pedal. I'm betting the resistor windings are shot and the "drive" signal isn't being sent to the motor controller. I broke out the multi-meter and started tracing power:

• 12 volts available from keyswitch to motor controller solenoid: Check.
• Solenoid engages when key is turned: Check.
• Resistance changes when key is on and accelerator pedal is depressed: Check. (This surprised me)
• 72 volts being supplied to controller input when key is on: Check.
• Controller outputs voltage to motor when pedal is depressed: Check.
• Double-check that voltage from the controller is present at the cables attached to the motor: Check.

So juice is flowing through all parts of the system and is fed into the motor but the motor doesn't turn. Something is "open" in the motor. Eww....that's not good. By now I've posted a plea for help on the newsgroup and more than one person has told me to check the motor "brushes".

The Postal Van manual just tells you how to drive the thing. It contains no repair information at all. I hope that the info in the Comuta Car/Citi Car service manual is compatible. The van has almost 10,000 miles on it by now so I'm starting to believe that brushes are my problem. The brushes complete the circuit by maintaining contact with the spinning commutator. The commutator is a mass of copper that spins in the center of the motor. The 4 brushes are in holders touching the commutator every 90 degrees around the commutator. As they wear, a spring keeps drawing them tight against the commutator to maintain contact. Eventually they wear down until they are too short to touch and the motor stops.

I crawled under and removed a dust collar and the cooling fan hose. I can see something...with a spring and a wire attached. That must be it. I disconnected the spring and pulled out a stubby block of carbon. It's barely 1/4" long. I've isolated the problem. Now all I have to do is find replacements for a 25 year old GE motor.

Glen, the fellow who sold me the van is very courteous and knowledgeable. He was actually concerned about my "EV experience" and wanted it to be positive. He actually found the brushes from a couple of sources and sold them to me at the lowest price: $50.00.

Consider this: An oil change today costs anywhere from $17.00 to $60.00 depending on if you do the job yourself or have a Jiffy-Change do it for you. You do this every 3-5,000 miles. I paid $50.00 for a 10,000 mile "oil change".

All I had to do was unclip each brush and unscrew the little pigtail from each brush. I slipped each new one into it's holder, clipped the springs on and attached the pigtail. It took 20 minutes. No oil, no filter. No hazmat. I washed my hands with ordinary bar soap when I was done.