bearman
Active Member
my EHC delete plan....with wiring diagram
I have studied the wiring diagrams for both the Wire Plus WP374 and the PDM retrofit from Big Dog. I have also studied the Thunderheart ASM4250 and ASM4260 (another option that some may not know about).
All of these EHC replacements have a computer in them just like the original EHC.
It is for this reason that I have decided to go the “total rewire” route on my Mastiff.
In preparation of the rewire I designed a wiring diagram to do away with the EHC, using the 2007 Big Dog wiring diagram as a starting point, then modifying it.
I have not installed this on my Mastiff yet but I have ordered all the parts I need and will start on it soon. I will take pics and add them when I start.
My plan uses 20 relays , 4 diodes, a timer, some fuses and a flasher (and a bunch of labor and some wire). It uses some of the original wiring, the stock Big Dog hand controls, and the stock key and ignition system. My design also uses a negative (-) command signal at the hand controls, just like stock.
Is it complicated?.... You bet it is (see below for less complicated versions). Can the average person do it?.... No, but we Big Dogs aren’t average people (or at least we know someone who isn’t). If you can follow a wiring schematic and solder a miniature relay to a printed circuit board (or know someone you can pay to do it), then you CAN do it.
The main thing is that everything should work like stock (or better) except for the headlight, even the 10 second self canceling blinkers and resuming of blinking after using the brake. My design doesn’t turn off the low beam when the high comes on, it just comes on with it so they both are on. This is illegal in most states (just the way I like it) so if you’re really worried about it you can add another relay to turn off the low beam when you turn on the High beam.
Only the starter relay and flasher is big (1 inch cube) like the ones found in a car. The other 19 relays and timer are about ½” cube, like you find on a circuit board. I plan on mounting them on one or two generic circuit boards from Radio Shack. I bought relays with a vibration rating of 6G (gravity) to 30,000 vibrations per minute, and a shock rating of 30G. I don’t know if they will hold up or not, but I mean to find out. The fuse ratings may need adjusting if any of them keep blowing, just be careful with them.
I have decided to put my design here for anyone who wants to see or use it. I did not use standard electronic symbols for everything but they should be self explanatory to someone who can read an electrical schematic.
I see several people on the forum here have dead Dogs with a bad EHC, and have a 5 or 6 week wait on a Wire Plus or a PDM.
The 3 position key designs are less complicated and could be even simpler if you leave out the horn and blinkers (and simpler still if you just wire the key to the low beam and do not use the high beam). These simpler designs use a positive (+) signal at the hand controls.
RESIST THE URGE TO USE THE BIG AUTOMOTIVE TYPE RELAYS FOR ALL OF THE RELAYS, THEY WILL BURN OUT THE HAND CONTROLS. You must only use the hand controls to power something that draws less than 1-1/4 watts (100mA @12v), the big car type relays draw about 2 watts, so you must operate the car type starter relay with a smaller relay.
Hopefully these will be of help to someone. Maybe one of them will get someone back on the road till their Wire Plus or PDM can come in.
These I offer for use at no charge to all the other Big Dog owners of the world, but use at your own risk, I take no responsibility for you not knowing the consequences of your own actions. I can email the larger size pdf’s (750kb) of the diagrams if you private message me your email.
Good luck
bear
I have studied the wiring diagrams for both the Wire Plus WP374 and the PDM retrofit from Big Dog. I have also studied the Thunderheart ASM4250 and ASM4260 (another option that some may not know about).
All of these EHC replacements have a computer in them just like the original EHC.
It is for this reason that I have decided to go the “total rewire” route on my Mastiff.
In preparation of the rewire I designed a wiring diagram to do away with the EHC, using the 2007 Big Dog wiring diagram as a starting point, then modifying it.
I have not installed this on my Mastiff yet but I have ordered all the parts I need and will start on it soon. I will take pics and add them when I start.
My plan uses 20 relays , 4 diodes, a timer, some fuses and a flasher (and a bunch of labor and some wire). It uses some of the original wiring, the stock Big Dog hand controls, and the stock key and ignition system. My design also uses a negative (-) command signal at the hand controls, just like stock.
Is it complicated?.... You bet it is (see below for less complicated versions). Can the average person do it?.... No, but we Big Dogs aren’t average people (or at least we know someone who isn’t). If you can follow a wiring schematic and solder a miniature relay to a printed circuit board (or know someone you can pay to do it), then you CAN do it.
The main thing is that everything should work like stock (or better) except for the headlight, even the 10 second self canceling blinkers and resuming of blinking after using the brake. My design doesn’t turn off the low beam when the high comes on, it just comes on with it so they both are on. This is illegal in most states (just the way I like it) so if you’re really worried about it you can add another relay to turn off the low beam when you turn on the High beam.
Only the starter relay and flasher is big (1 inch cube) like the ones found in a car. The other 19 relays and timer are about ½” cube, like you find on a circuit board. I plan on mounting them on one or two generic circuit boards from Radio Shack. I bought relays with a vibration rating of 6G (gravity) to 30,000 vibrations per minute, and a shock rating of 30G. I don’t know if they will hold up or not, but I mean to find out. The fuse ratings may need adjusting if any of them keep blowing, just be careful with them.
I have decided to put my design here for anyone who wants to see or use it. I did not use standard electronic symbols for everything but they should be self explanatory to someone who can read an electrical schematic.
I see several people on the forum here have dead Dogs with a bad EHC, and have a 5 or 6 week wait on a Wire Plus or a PDM.
The 3 position key designs are less complicated and could be even simpler if you leave out the horn and blinkers (and simpler still if you just wire the key to the low beam and do not use the high beam). These simpler designs use a positive (+) signal at the hand controls.
RESIST THE URGE TO USE THE BIG AUTOMOTIVE TYPE RELAYS FOR ALL OF THE RELAYS, THEY WILL BURN OUT THE HAND CONTROLS. You must only use the hand controls to power something that draws less than 1-1/4 watts (100mA @12v), the big car type relays draw about 2 watts, so you must operate the car type starter relay with a smaller relay.
Hopefully these will be of help to someone. Maybe one of them will get someone back on the road till their Wire Plus or PDM can come in.
These I offer for use at no charge to all the other Big Dog owners of the world, but use at your own risk, I take no responsibility for you not knowing the consequences of your own actions. I can email the larger size pdf’s (750kb) of the diagrams if you private message me your email.
Good luck
bear
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