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Tundra blowing bulbs. Help!!!!!!!

Posted: Mon Dec 11, 2006 7:36 pm
by COS
A co-worker has a Tundra II that will not regulate the voltage on the lighting circuit. He bought it used. Someone prior has installed hot-grips. Everything worked fine at first.

He noticed one day his hot-grips were extremely hot to the point it melted the hand grips. It also blew the only two bulbs on the machine. (head lamp & tail)

He fisrt replaced the voltage regulator and hot grips: No help.

I gave him a hand and look all the wiring over. We pulled the seat, gas tank & air box. We noticed the butcher job on some splice work. We inspected & cleaned up all the hacked work. The Voltage Regulator (VR1) is a two wire type and two ground wires from the chassis are grounded on the VR1 mount bolt.

I ohmed out the hot-grip system and they check out and are not grounded to the chassis. I also checked continuity between the chassisand VR1 case. (less than 1 ohm) I checked for lighting supply lines shorted to the chassis- all good.

We started the engine up and get 14 volts (A/C) at idle. When the RPM starts to climb the voltage ramps up th 40 VAC right away.

I convinced him he had gotten a bad regulator. Tonight he installed yet another (new) regulator only to have the same problem.

Does the CDI have anything to do with the lighting? I know the 2000 and up Yammies do.

Any suggestion are appreciated.

Posted: Mon Dec 11, 2006 11:03 pm
by YamahaMountain
Does the Voltage ramp up with the Hot girps on and off? Are the Hot grips wired in properly? I don't know much about wireing but thats where I would start.

Posted: Tue Dec 12, 2006 7:19 am
by john
CDI does to a point, but I believe it will either work or not. Blowing lights and the overheating of the hand warmers sounds more like a short.

The short could be sporatic. Try disconnecting the hand warmers and see if that fixes it, if not, do the same to the lights one at a time i.e. head light, tail light. Test your regulator and buy lots of bulbs :)

I had a short on an old Panther once and it took forever to find it, ended up re-wiring it, which is when I found the short, a small bare wire I couldn't see till I took it out.

Posted: Mon Dec 18, 2006 9:21 pm
by YamahaMountain
Any update on this COS? Did you guys trace it down or are you guys still looking?