HELP!!! 620 RXC electrical problem

[JimboBillyBob]

I have a strange problem with my 95 620 RXC.

My lights/electrical on the instrument cluster have stopped working for the most part. The only operational part of it is the left turn signal. No right turn signal, neutral light, gauge lights, high beam indicator or temp indicator (never seen that one on).

I have checked all of the connectors in the headlight area for corrosion and they all appear to be in great shape and making good contact. I have also checked the grounds and also the frame ground and they look good also.

Since most of the wiring runs through the control switches on the left bar, I took that apart looking for a short, corrosion and just plain dirty contacts and found some dirt (which I cleaned) but that was it. Once reassembled, the instrument cluster is still out and the headlight still doesn't work (when running of course). :(

Has anyone seen a similar problem? I'm stumped because the bike runs great.

Thanks,

JBB

 

[gasgasman]

You might want to check the fuses in the fuse box.

 

[TexKDX]

After you check the fuses as gasgasman said, stop by the local auto parts store and get a tube of dielectric grease. Also procure a small piece of sandpaper. Get out the wiring diagram in the manual.

Start down at the regulator/rectifier under the right side panel and work your way up. Pull the connectors, clean them with the sandpaper, and coat with the grease. Put back together. Work your way up to the front.

The bad news is on the RXC all the lighting runs thru the ignition switch. After going thru all the connectors, if the lights still don't work, then consider replacing the switch. If you have a multimeter, you can test for power going into the switch. If it is not coming out, then you know where the problem is.

Lastly, are you SURE that all the other lights are not burned out? If your regulator went belly up, as they are prone to on this bike, then maybe they are all out from that. You just have not reved it high enough to burn the last bulb out while switched on. The KTM replacement part is $167. Baja Designs has a regulator/rectifier they sell for about $25. I put two of these on '95 RXCs, one a 400 and one a 620. I lost my instrument lights on the 400 this way and kept losing the head and taillight until I replaced the unit. On the 620 it just went bye-bye and had no output at all.

 

[JimboBillyBob]

GGM - I checked the fuse and it is good. I wish it were so easy.

TexKDX - It's odd that you would make such a suggestion (getting a rectifier/regulator from BajaDesigns). I sent them an email last night asking if thier assembly would replace the stock one. Seems we think alike (I've got a '94 KDX250 also). Regarding the assembly, which one did you purchase? I only saw one listed on thier site and it didn't seem to be model specific. They also had a separate voltage regulator unit but I haven't a clue if I need them both. I assume the stock unit on the KTM is a regulator/rectifier but the parts manual just calls it a voltage regulator.

I checked the connections last night but didn't grease them...but since I still have it torn down, I will definately get some grease on them. While fooling around with it, I noticed a small crack in the epoxy on the regulator (about 1/2" x 1/64") and also, it looks like there is some swelling but since I've never seen a new one I can't be sure.

I plan to check it tonight and measure the voltage coming out of it (borrowed a Fluke DMM) just so I can be certain. I'll test the cap also but I really think it's the regulator.

On the lights, I still haven't checked them to see if they are burned out or not. I'll get to it though...I suspect that they are blown and really, it would make sense with the exception of the neutral light. I don't tend to rev the bike up with it in neutral but I suppose it could have happened during a missed shift.

Any additional info on the Baja Designs regulator/rectifier would be greatly appreciated.

Thanks much,

JBB

 

[TexKDX]

JBB, the regulator/rectifier may not be in the catalog but they have it. Alan Roach, the BD owner, even rigged up some wiring and connectors so it went right into the two RXCs I fixed. Yes, the stocker is a regulator/rectifier. The big givaways to this requirement are 1) a DC flasher unit and 2) battery charging capability. You can do an AC system with just the little $14 AC regulator if you don't have to charge a battery. For example, if you want to convert an enduro bike like the KDX and want turn signals then get an AC flasher and skip the rectifier. It just won't light the lights when the motor is off and you will have more light pulse at low RPM. If you want to charge a battery then the DC conversion is required.

I'm doing this from memory so bare with me. Your RXC puts out two phases of AC from the stator. The unit you get from BD will take the two phases in and combine them to one DC output that will feed the rest of your system. I believe it has 4 wires - two AC phases in, a ground, and the DC out.

The crack and swelling you are seeing on the stocker are indicative of a heat-related failure. Both of my boxes did this. I'd send you a pic as proof but just threw them out when cleaning up the shop a few weeks ago. Both replacements have been in place for 2 years now and are running fine.

If you get stumped let me know and I can go shoot a pic of the re-wired setup and email it to ya. Pretty simple stuff though, that is the stator output going into the r/r and it feeding the system. It is up by the ignition switch where things get ugly with lots of wires. Good luck!

 

[JimboBillyBob]

Thanks Tex! That's exactly the kind of info I was looking for. I am going to go ahead and contact BD again as I haven't heard from them and see if they can get one out to me.

Thanks again,

JBB

 

[JimboBillyBob]

Fixed I think!

I got the regulator/rectifier from BD and installed it. Had to make the connector for it since they didn't have one that was wired up alread but that was no big deal.

Made 2 trips to AutoZone to get replacement bulbs for almost everything (the right side blinkers weren't blown but everything else was) and salvaged the one oddball bulb (backlighting for the instrument cluster) from a V45 Sabre cluster I got just for the tripmeter knob.

One bulb I was unable to locate was the headlight (it's a H5 Halogen type that nobody seems to have) but that was no big deal as I had a spare headlight assembly with a H4 Halogen bulb in it.

At this point, all lights are working in the insturment cluster as well as head/tail and directionals. I'm legal again...almost...it seems that the batery got killed by the blast of current and probably fused the plates so I'll have to get another one if I want the parking lights to work when it's not running.

Time will tell if the new regulator will hold up. I am concerned becuase it doesn't have the massive heat sink that the stock unit has...in fact, it has no heat sink at all.

Thanks for everyones input on this...now if I can just get the timing/carb set to where it doesn't knock in the low RPM range I'd be real happy.

JBB

'95 RXC 620
'94 KDX 250
'87 Super Magna
'86 IT 200
'76 CB 360 (newest addition)