dew05001

Sounds easy enough, I will just try to pull it out and report back.

I believe I have located all my issues. I replaced the rectifier and that has fixed the issue with the battery not staying charged. Now, on to the brake light issue. I found today that the front brake switch looks to be broken, which I imagine would be the reason the brake light is always illuminated. Question is now, how is this replaced? I have found the part on ebay, do I just pull apart the throttle where it has the "Run/Off" switch and replace the brake switch and plug it in the two bullet connectors?? Seems easy enough, any tips would be appreciated. Thanks.

I will check this as soon as i fix my battery. I removed it last night to charge and upon reinstalling, the male connector on the negative side broke off. I will get a new one tonight and solder it when I have time. I will report back once I have tested the various points. Thanks.

Sorry to revisit the issue, but it seems my battery has lost its charge again. I charged it last week and now it is dead again. Is there a part on the bike that is similar to the alternator on a car and is responsible for keeping the battery charged? Thanks.

Ill give that a try. Thanks.

Results from testing the battery: Ignition in the OFF position: 6.07 Ignition in the ON Position: 5.73 Running Idle: 6.45 Running @ 3000 rpms: 6.56 Results from using the jumper wire: FIrst off, I clipped one one end of the jumper wire to the battery + and i had exposed wire on the other end of the jumper wire. I then proceeded to unplug the turn signals and brake lights from the female connectors and tested using the male components and the live end of the jumper wire. When touching to the turn signals the lights illuminated and were solid, which I expected, since I was by passing the relay. The tail light had 3 wires: Yellow, Blue and Black and using the jumper wire I got the following results Yellow: Normal running tail light Blue: Bright Tail LIght Black: Nothing Should I be using the jumper wire differently?

Could you explain how the jumper wire works just clip red to red and red to brown? When I run a wire from the battery + to a brown connector what should i be looking for should the blinker illuminate and stay solid or flash? Do I need to mess with the blinker switch at all? What should I be looking for in the brake light?

I just charged the battery last night, I will test the voltage again tonight and repost. You mentioned a "bad earth" what is that? Is there multiple? If so where are they located and what is the best way to clean them? Thanks.

So I found the rectifier and completly removed it from the bike to test..(is that correct?) I was able to get a noise from the voltage meter when tested as follows: Voltage Meter Rectifier RED----------------------White BLACK-------------------Red I charged that battery and took the bike for a 15 min ride and the power to the blinkers, horn, and tail light were all restored. My next issue is with the tail light.. It does not brighten when i pull the hand brake or engage the foot brake. It will brighten when I flip the light switch from low to high. Lastly, the tail light is flashing with the turn signals. Any ideas? This is the relay I am using: http://www.ebay.com/itm/Yamaha-Turn-Signal-Flasher-Winker-Relay-NEW-DT250-DT400-DT50-/310442627308?pt=Motorcycles_Parts_Accessories&fits=Year%3A1975|Model%3ADT400&hash=item4847d290ec&vxp=mtr The original had 3 connectors, this one only has 2 and the black wire is left open as of the moment, when I touch the black wire to the engine, in attempts to ground it, nothing happens. I am getting a message saying I am unable to attach images in this forum, so if there is a way to do that let me know and I will post some.

Thanks, I will check out the rectifier tonight when I get home. What is the best way to test this? Does the bike need to be running? Thanks.

Cynic: I tested the battery and when the bike is off the battery was at 5.65 and at 3000rpm it was 3.53. Airhead: When I first got the bike and put a new battery in it I could only get the signals to illuminate, but not flash. So I was told in other forums to swap out the flasher relay. The original relay had 3 connections, but I had a hard time finding a reasonable priced 6v flasher relay with 3 connectors that said it was compatible with the dt400. So I bought an after market relay and I had to swap out the original connectors for female attachments. I hooked the solid brown to the X and the brown/white stripe to the L and the instruction said this flasher did not require the black ground wire. Black: I don't know I I can say I got it to work because as soon as I buzzed off a 1/4 down the road it stopped working. Thanks for the help everyone.

If you couldnt tell, I am a newbie. I totally spaced to check the voltage. I put a new battery in it last month, but it would make sense to check that if the horn is out too. Ill check that tonight and repost.

My turn signals are causing me a major headache. Let me give you some background: BIke has new 6v bulbs all around. New Flasher relay (2 prong its so hard to find a 6v 3 prong - so i have a ground that is wide open) Brake light no longer illuminates when I pull the brake and when I installed the new flasher relay it worked for about 5 minutes and now the blinkers and horn dont work. **Headlight works fine** Fuse is still good, even put in a new one and it didnt make a difference. All the bulbs are still good. In Short: -No Horn -No Turn Signals -Tail light comes on but does not brighten with brake PLEASE HELP!

Hello everyone. I recently picked up a 1975 DT400 that has just a few quirks I am trying to get worked out. I am hoping to do most of the work myself, and have my fingers crossed that some of you have the know how to help! Thanks.