Sporadic Electrical Issues

[Ole Bigz]

My buddy has an '03 Big Dog Chopper and has been having some electrical issues. The brake light and turn signals have only functioned intermittently for the past few months. Running lights on the brake and turn signals work fine, but they don't go brighter when depressing the brake or turn signals.

I just wired up a new brake light/license plate housing for him yesterday. When we checked the wiring from the bike when putting it on, the running light had juice but nothing from the brake side (both hand and foot). He called me late last night and said that if he puts the high beam on, the brake light and turn signals work fine. There are other electrical problems, such as the speedo not working, but we're more concerned with getting him back to legal so he can get it inspected. Since he's the third owner, there's no way of telling what Mickey-Mouse BS has been done to the wiring up to now that I cannot see at first glance. He's running LED's for the turn signals, but in my checking it over, I don't see a load equalizer. That being said, he did say all of the functions worked a while back. I have to believe the issue is a short somewhere in the system since the brake and turn signals sometimes work; if they stopped working when the LED's were put on, then I'd say a load equalizer may be needed.

That the high-beam seems to solve the problem has really got me stumped. I f'ing hate wiring, by the way!!! :bang:

Does anybody have a wiring diagram for an '03 Big Dog or have any advice on where to begin looking for a short or other issue so I can get this fixed for him?

Thanks

 

[Raywood]

Hey Ole Bigz, glad you made it over here.

A few things you need to know about the BD wiring system. Most things go through the EHC under the seat. It's a low voltage wiring system so when people change things like lites, horn or something else it has consequences!
My old 03 as well as a couple of my buddies even had issues if we changed the spark plug wires that didn't provide enough resistance.
All BD's since at least 03 have had LED turn signals. The 03's blinked three times when brake was applied. I don't have a wiring diagram for you but someone on here should be able to hook you up.

But, I would say his EHC needs replaced just from the things you mentioned so far. Also understand that these bikes need a full load in the battery and should be on a battery tender all the time as the EHC actually drains the battery everyday a little bit.

If you could give us a discription of what changes have been done to the bike from headlight to spark plug wires we may be able to help you a little more.

Good luck,
Ray

 

[Ole Bigz]

Thanks, Ray. The blinking during braking is what it used to do. The only mod's I'm aware of are smaller LED's on the front and back and I replaced the headlight a few weeks ago after he had a run-in with a cager. We replaced the rear LED's a while ago becuase one of them busted. Now that I think of it, he mentioned the brakes might have stopped working about that time. The replacements were the three wire style (brake, running, ground) and pretty muched looked like a direct replacement for the ones that we took off (which were already smaller than the stock ones that probably came on the bike). The other mod is a new LED license plate/brake housing attached to the primary. When I tested the wiring on it yesterday before hooking it up, the brake wire had no power when the brakes were pressed.

What does a new EHC run and is there any way to test the one he has? If it's too much coin, I may suggest that he get a whole new wiring harness from Wire-Plus. If it was the new LED's out back, is their a load equalizer I can run to take care of it?

Thanks

 

[Cephus]

Ole Bigz, I have the owners manual for an 03 if you need it. If you send me a PM with a fax number or address I can send it out right away.

 

[WB Cycles]

Ok .. the good news is that both the 03 Chopper and the 03 Daytec Chopper use the same EHC. BDM170-00094 at $268.16

There is also a Service Bulletin out covering the addition of addon electrical components:

SYMPTOMS: Incorrect electrical component installation resulting in a damaged EHC.

• Reversing the positive and negative leads during installation will cause irreparable damage to the EHC.
• DO NOT attempt to splice wires for the EHC. Splicing wires will cause the EHC to malfunction requiring replacement.

 

[backon]

I have the service manuals for the 02-05 BDM bikes shows the electrical for that year it's 47 pages in pdf I could shrink it and email it to you if you send me a email addy.

 

[Gas Man]

What branded LED's did you use to replace? The problem with LED's is resistance.

Also, another thing... check the EHC connections... they may need some di-electric grease.

I can post pics of my EHC but I think the 2003's look different...

 

[CCRainman]

The 03 look nothing like that Gas. They are push in platic connectors.
Check out ASM3250 Thunder Heart Electronic Products

 

[Ole Bigz]

Thanks, guys. That'll give me a good place to start. I'm going to pull the leads for the rear LED's first to see if that's causing the problem and start the process of elimination from there.

 

[Gas Man]

I know Rain.. but I thought it was somewhere to start. But I don't have one and don't have a pic of it.