DRZ400 E to S Wiring Harness Conversion Trouble [pics included]

A few years ago, I bought my 2001 DRZ400E used. From that time up until a few months ago I only used the bike off-road and eventually the botched wiring job that was put together by the original owner began to deteriorate. With gas prices rising, I decided I wanted a bike to get me around the city and thought the easiest solution would be to upgrade my DRZ to be street legal. The first step would be for me to upgrade the wiring harness to a reliable and working condition. I purchased and installed onto the bike a 2005 DRZ400s wiring harness and just got my 2005 left and right switch assemblies in the mail tonight. However, what I got was a wiring harness that does not match the switch assemblies I had purchased. I'm not sure if the wiring harness or the switches I purchased were the wrong year or what, but I am hoping some of you might be able to help me out so I can get my DRZ back and running (and hopefully on the road) soon. I included some pictures to demonstrate my point.






I'm not sure what to tell you. An S has a lot more wires than you will ever use converting an E to street legal. Instrument cluster and interlock system. As far as I know, there are only 2 wire harnesses used on the S and they were not very different but the connectors may not be compatible. You have the basic switch functions, you can make it all work even if you have to adapt some of the connectors. Start with a wiring schematic and identify the wires you need. Identify the wire colors and use the appropriate wires. You will need brake light switches, headlight, tail/brake light, turn signal lights and horn. It has always been easier for me to make a harness than adapt one but it is not impossible. The E has no neutral switch so forget that. The S harness will need a slight mod for the CDI box. The green wire in the larger connector needs to be open circuit for the E box.

Thanks for your input noble! I was wondering if anyone could confirm/identify the year of the harness and/or the years of the assemblies so I could figure out my next steps. I'd prefer buying the matching assemblies if possible so that I don't have to botch the wiring on the harness.

You have the late style harness, the give away is the triangular plug for the speedo. Everything else is the same on all S and SM's

All S/SM parts will fit. Speedos will fit too, if you have the old four wire speedo, all you do is connect the gray to the orange wire and install the trangular plg to mate to your harness.

William, thanks for clarification on the wiring harness. However, if the switch assemblies and their connectors are the same for all S/SM models, then why don't the switches I bought fit into the wiring harness I have? Am I supposed to have more equipment than the wiring harness and the switches in order to get this operating? Thanks again for all your help so far.

Possible you are trying to plug in the switch gear in to the wrong connectors. I know for a fact (for example) that a E ignition switch will plug right into a S/SM harness. I just so happen to have teh same harness sitting on the floor of my office at the moment!

In you last picture, you are holding:

White Triangle plug - Power to the speedo

Big box shaped plug - Interlock relay (see the FAQs for a simple method to jumper it) This relay is also the relay for the turn signals so you may wish to do some customization.

Yellow plug - Mates to the left switch gear

Black plug - Mates to the right switch gear

Little grey plug - Mates to a turn signal

Black and Yellow plug - Mates to the S/SM indicator lights (High beam/turn/over heat/turn)

Okay, I must have been sold the wrong switch assemblies then. My right switch assembly has a 7 pin male connector and my left switch assembly connects via 7 pin female connector (as shown above in the pictures). Whereas the harness only accepts a 6 pin female and male connector, respectively, for both. Am I just missing something or do I have the wrong switch assemblies?

Sounds to me like you have the wrong switch assy's. They are supposed to be 6 pin.

Recently I purchased a new start switch that has the correct 6-pin connector. Correct me if I am wrong but the newer model SM switch assemblies have the 7-pin connectors (there are multiple 7-pin switches selling on eBay listed as DRZ400SM). Regardless, I installed the new switch onto the "S" harness but the bike will not turn over or start. I have unplugged the green and pink wires running into the large CDI connector, still with no success. Initially I only removed the green wire, however after further research I discovered I wouldn't need the pink wire either as from what I understand I do not have the neutral switch on this bike (which is what the pink wire connects to) but please let me know if I am wrong in this understanding. I also do not have the kick stand or clutch switches on the bike so I am assuming there is no need to bypass anything for the bike to start up.

I know that the battery/stator/spark plug/fuse is good, I am able to start the bike using the old "E" harness and start switch.

My concern is that I am missing something regarding bypassing the kick stand, clutch, or neutral switches by altering the harness somehow (I have no idea what though). I have included pictures to illustrate what I have done so far.

CDI connection with green and pink wires removed (the bike still doesn't start with the pink wire connected and the green removed):


Start Switch connection to harness:


I am assuming that these wires running out of the start switch connects to the brake reservoir wires:


Any help to get this bike running again will be greatly appreciated, and thanks!

Do you have the interlock relay? You need to bypass anything you are missing.

HOW TO: bypassing the interlock relay LINK(from the FAQ)

NOTE: your 'E' CDI needs to NOT be pulled to ground for enable which is opposite of diagram in above link. If you compare how the stop switches work between the E and S/SM you will see E is momentary contact of ground to stop engine. On S/SM a constant supply of 12V keeps it going, off stops it. The switch in the diagram for S/SM is kinda wrong, since it is really 'on' when the switch is out, and 'off' when the switch is in. Looks opposite in the picture. Simply switching the power on/off like the S/SM will work with the E CDI too.

wiring diagrams for S/SM models, and E model.

To get it to crank you just need to get +12V to the yellow/black wire. To make it fire you need (at the CDI)power on orange and NO ground on green (unplugged works) plus the other wires.

wiring diagram drz400s-sm.05on.jpg

wiring diagram E drz400e_2000on.jpg

Edited by slowriding

Old topic, and I'm new (I just registered to post this...)


Been working on a KLX400 that had a bad lower crank bearing. 


Long story short...I ended up putting what I believe is a DRZ400SM harness on it. Has plugs for a fan, thermostatic relay, and such. I wanted the plug and play hand controls....


Tons of diagnosis and running around to get things to work when really, it was never that hard. 


At first, it wouldnt turn over or start at all. Nothing. I would jump the solenoid and just get sparks...

The starter was bad. A quick rebuild later and a bench test proved it was working after repair. 


Reasembled and would get nothing out of the starter button. Took it apart, rebuilt it, nothing. Traced the wires to the relay. Hit the relay out of frustration. Boom- engine turns over. 

Relay was on the fritz. Replaced with a new one with LED flasher built in. 


But still no spark. This thread was what solved my problem. 


I Had originally soldered the kickstand safety switch wires together. 

I was convinced the neutral switch was also locking out spark somehow. 


As a last ditch effort before removing the stator to check the magnetic pick up, I went to remove the green wire from the computer. I accidentally cut it...


but no matter- Spark!!!

So for my case, with the SM harness on the KLX400 model all i needed to do was disconnect the green wire to the computer. That's it. 


Have not started it up yet, but have a nice blue spark. 


Thank you all for your info on this thread. You're a wonderful bunch of folks. 


I just installed a SM harness on my E project. Soldered clutch and kickstand safety and got the engine to crank, but did not start. Cut the green wire from the CDI and Bang. Working just like before!!

Thanks guys.


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