New member to forum. Great input and hopefully I can be of help to someone in future. But now, I need some advice. First a little background on the problem. My neighbor and my son were returning from deer hunting with neighbors 2002 500 Auto 4X4 when they looked in the mirror and lo and behold saw the Cat doing cartwheels down the freeway. Someone didn't double check the tie down. Neighbor took it to dealer who said 3500+ to fix. He said no and asked me to see what I could do as I have fixed his riding mower several times. I've got it pretty much back together and looking very close to original (one tough ATV) but have not been able to start. No spark. I have replaced and tested starter relay, ignition coil and spark plug. I have tested voltage at 12+ to ignition switch but depressing switch does not engage starter. Bypassed switch and spun starter with direct charge from battery. Lights and accessories work. Also, pull start does not generate spark. Key is in on position for all of the above. Oh yeah, visual inspection of wiring didn't show any bare or loose though there are areas which didn't get a real close look.

I have the manual and wiring schematic so I think it's narrowed down to the CDI unit - which the manual says rarely goes out - and the regulator but as a shade tree mechanic I am scared of little but confused by a lot.

I could use some directions on testing the CDI unit and regulator or other things I need to check. Also, I couldn't find in the manual what parts (electrical wise) have to be in good working condition to not break the "loop". For example, the indicator light board was broken. But it has been delegated to a future purchase since I didn't think it was absolutely necessary to normal operation.

Thanks in advance for any advice. I'm ready to ride this for a while (my fee for reparing). Besides, my other son needs to rebuild the engine in his car so he needs my shop. Never ends.

 

First make sure the run/stop switch is working right or else you get no crank and no spark.

 

Opened the handlebar control assembly up. With run/stop switch in on position and the red lead to the orange wire and the black lead to a ground on the chassis, read 12+ volts. In off, no volts. Nothing appeared to be damaged inside the assembly though the choke cable had slipped out of its little slot - would have missed that.

 

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A long time ago, my 2002 AC 500i-Auto lost spark as well. "With luck under 5 minutes" I discovered a wire connector was unplugged. This wire ran down the front steering column and its connector couldn't be reach from the top or from the bottom. GGGRRRR. So, I tore apart its front end (racks, plastic, etc.) and "plastic glued" this connector back together. Its been running great ever since. If you can, trace all physical wires. If you find two matching plugs that seem to be unplugged from another, that might be its problem too.

Hope this helps....

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There are test for the CDI in the manual that can be done with a simple Volt/Ohmmeter. Then check the coil. Also I doubt your problem is the regulator/rectifier.

 

Pulled the rack and front end plastic off and checked all wiring up close. Everything in order. Pulled CDI unit out and tested. 6 out of the 12 pins showed no activity on the meter at all. Turned the key on with the run/stop switch set to on and checked the voltage on the orange/white wire in the 8-pin plug which connects to the CDI - read 12+ volts. Voltage into the CDI but nada out. Figures it would be the most expensive electrical part which is bad.

Out of curiousity, do you think the jarring from the cartwheels did the CDI unit in? If not, what are some of the causes for failure?

By the way, thanks for the responses. Always great to have someone to seek advice from.

 

The cartwheels may have done it, but usually these CDI's either have some little part it them die or have a voltage spike kills them.

 

tphowell,

This is a little off topic, but I have a 02 500i and I need a wiring schematic. The service manual I have has a reference to the schematic in the contents, but the referenced page is blank in the manual.

Do you think you could send me a copy of yours via email, fax or something? Email is atvconnection@accuspec.biz

Thanks for your consideration.
Tom